TWiP v3 275

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About Vincent



Thursday, 25 May 2017 10:01

TWiP 134 Letters

Written by

Case guesses:

Nita writes:


   Hello to the TWIP-tastic peeps! I missed Dr. Despommier on the last episode, but I had a great time listening in! For our last case 132, I did have a fun memory to share! Growing up in Taiwan during my grade school years, we would receive packets of slippets that had a target bulls-eye pattern that was sticky on one side to bring home. Every family member would stick it on their butts to essentially perform their own Scotch-tape exam, cover the sticky side with the clear plastic to keep whatever you stuck on your butt on the adhesive end, and bring them to school. Picture of what this looked like is in the link here:

   I have no idea who looks at all these packets, but I would guess someone in the health office (maybe the nurses or local doctor assigned to the school) would be the sad fellow appointed to this wriggling mess.

   Onto my guess for case 133, the young Haitian child suffering from failure to thrive with observed motile worms in feces opens the can of worms to a few possible differentials, notably, ascaris lumbricoides, hookworm, or whipworm. From this list, I think ascaris lumbricoides is probably the most likely answer. This is an intestinal parasite that clogs up the lymphatic system, which can explain our patient’s edema. It can also result in intestinal obstruction, which can manifest in the protuberant belly as this worm can multiply and grow quite large (as seen in the photographed preserved jar from the Meguro parasitological museum via my sneaky photo skills). Nutritional deficiency can result from the obstruction and the energy siphoning from the worms. The patient likely was infected through the fecal route with poor sanitary conditions. With earth floors, it is easy to track in infected dirt or with unsanitized water source, the worms may also be ingested. Usually, the worms are also found in the pulmonary system (as is the hookworm).

Diagnosis is done by stool microscopy, and I think the standard treatment can be albendazole 400mg PO or mebendazole 500mg for those older than 2 years old. Also, “everting uterus” from the pinworm made me giggle. What a great way to describe this! Thanks again for continuing the awesome podcast.

David writes:

Dear Hosts,

Judging from Daniel’s hints regarding a certain image in a book as well as adding up the factors described in the current case (abdominal discomfort, distended belly, lack of nutrition compared to her sister, long motile worm in the feces), I will venture a guess that this young girl has been infected with Ascaris lumbricoides. She most likely contracted the parasite eggs after coming into contact with soil or water contaminated with feces from her impoverished environment. I came across a link that states Ascaris is one of the most common worm infections in Haiti (, and I hope this little girl received the treatment she needed (treatment for this parasite [ascaricides] are albendazole, mebendazole, levamisole, pyrantel pamoate).

Thank you once again for the informative and entertaining podcasts

Sincerely, David P.

Molecular Helminthology Lab

Tufts Cummings School of Veterinary Medicine

Wink writes:

Dear TWIP Team,

I found the picture in your fantastic text, so I must say ascariasis with a heavy worm burden. But I was wondering if strongyloidiasis would also fit this case. I was thinking about the latter because of the edema on the abdomen and wondering if the immune-deficiency of malnutrition is sufficient to lead to hyper-infection.

Wink Weinberg (Atlanta)

Trudy writes:

Dear TWiPpers,

I think the girl is infected with Strongyloides stercoralis.  She probably contracted the parasite from the dirt floor in her home, as Strongyloides is one of the few parasites which can penetrate unbroken skin.  It could also be Strongyloides fuelleborni, but I’m going to stick to stercoralis.  

As an aside, other parasites which are capable of penetrating unbroken skin include schistosomes, cercariae, and hookworm.  I learned this from Dickson.  Thanks, Dickson!



Iosif writes:

Dear Twip Team,

My differential for this case would be that our young patient has an Ascaris infection. These large worms can live in our GI tracts and have a life cycle similar to Strongyloides, but without a reinfection. Our patient probably had food contaminated with ascaris eggs; from there the eggs would hatch within her GI system and the larvae would then spread via the blood vessels or lymphatics to her lungs where they would climb up the bronchi and then trachea and be swallowed so that they could live their adult lives in the GI system. Judging from her lack of lung symptoms and her short stature as compared to her sister, this infection is most likely a chronic one and she has thus lost a lot of nutrients over time. Thankfully it does not appear that full blown kwashiorkor or marasmus has developed, and without a painful belly I assume that there is no current GI or biliary obstruction. A stool sample could be used to look for eggs. A single dose of albendazole could be used for treatment.

I hope that she had enough catch up growth that she could at least match her sister in height.


Iosif Davidov

PS I had forgotten that you guys asked for audio clips for our differentials so I tried to do one for this case. I was pretty nervous making this so I do apologize for any awkward pauses. If this goes well then I will try to continue using audio files.

Elise writes:

Dear TWIP Trifecta,

I hope this finds all of you well.

Look at me, back in the swing of things (I hope) writing with a diagnosis (although the last one I submitted was late).

I suspect that the little girl Dr. Griffin met in the Dominican Republic is the victim of a substantial infestation of Ascaris lumbricoides. Initially, I thought that she suffered from something a little less dramatic but when I heard the detail of the mother actually seeing a large motile worm in her daughter’s stool, I revised my thinking.

The patient and her family live in conditions that are ideal for contracting this nematode. They are in constant contact with dirt and there is poor sanitation where they live. In addition, children are more likely to become more symptomatic and more adversely impacted by a roundworm infestation because their intestines are so much smaller than those of adults. It is not uncommon for people infected with ascaris lumbricoides to experience very few symptoms unless they are hosting a lot of worms. Younger children are more likely to have symptoms and be negatively impacted by an infestation, most notably by failing to grow properly due to not being able to absorb enough nutrients (as is the case with this child).

There is another possible parasitic suspecting this case: Trichuris trichina, or whipworm. Like ascaris, this is a soil-transmitted parasite, but the symptoms of a Trichuris infection (and since this case has appeared in such a rural area and there is little access to sophisticated testing, the little girl’s symptoms seem to provide the best guide for a diagnosis) involve much more obvious stomach upset: abdominal pain, nausea, bloody diarrhea, sudden weight loss. The patient in this case seems to have much more chronic symptoms most crucially failing to grow and her distended belly, which points more towards ascaris.  

In both cases, the most common treatment appears to be with mebendazole or albendazole, however this patient’s case seems so pronounced that I wonder if she needs some surgical intervention too, to remove the worms that have proliferated so much in her body.  

Thank you so much for your work. I hope all is well.

Elise in lower Manhattan.


Elise writes:

Dear TWIP Trifecta

How are you? I hope to be reporting that I am back from beyond and that I can be a responsible TWIP contributor. It has been a pretty chilly spring in lower Manhattan and all kinds of rain is predicted for the future.

I suspect that the young mother and her son described the case from TWIP 132 have pinworm infections. The symptoms are consistent with the basic pinworm signifiers: itchy anal areas, itch gets worse at night (while the pinworms are laying their eggs). While the woman would like to suggest that her sister’s children are the vector for this infestation, and she may be right because children often share pinworms with one another, her volunteer work with lots of children also provides other opportunities for infection. (Still, her sister’s kids, since they stayed in the home for a while are the most likely suspects. What was the verdict when she asked her sister if her kids had any symptoms?)

Diagnosis can be done in a variety of ways: looking for live worms around the anus and in bedclothes, or using tape around the anus first thing in the morning to collect eggs.

If pinworms are present, the entire house will need to be cleaned and all clothing and bedclothes washed with hot water. Everyone should be treated. Some people have no symptoms even when they have a pinworm infestation and unless everyone is treated, pinworms can come back and run rampant again. Everyone in the household will need to follow the medication protocol at the same time to ensure that the pinworms have been eradicated from all hosts. Getting rid of pinworms is tricky because everyone needs to take the medication and take great care with hygiene.

Thank you so much for all of your work. I have missed being a regular contributor.

Many best wishes,

Elise in lower Manhattan

Scott writes:


There was a bit of confusion expressed in the current TWIP about the candirú, a parasitic catfish of the family Trichomycteridae and native to the Amazon basin, that was discussed at some length.  As a serious freshwater aquarist, I have been aware of this fish since first reading the account of it in Gunther Sterba’s 1966 classic, “Freshwater Fishes of the World,” which includes a drawing of it.

I would recommend a fairly complete and informative article in Wikipedia about the species, Vandellia cirrhosa, the species in the genus most commonly blamed for being a human parasite. It is interesting to say the least, and worth the time it takes to read.  Seems that it’s not as scary as one might believe, considering the Internet legends and general misinformation circulating about it.  But it is an interesting species, with an interesting lifestyle, nevertheless.



Cartago, Costa Rica

Monday, 15 May 2017 09:15

TWiP 133 Letters

Written by

Case guesses:

Iosif writes:

Dear Twip Team,

My guess for this case is Entorobius vermicularis aka pinworm. This parasite is extremely common with greater than 10% of the US population likely being infected. Infections travel via the fecal-oral route with eggs being ingested leading to larvae growth within the small intestine, from there the larvae matures to an adult and sets up a home within the cecum and appendix of the large intestine. The adult females migrate to the rectum and out onto the perianal folds (usually at night) and lay their eggs in that area. The adult worm and eggs can be irritating which leads to the itchy anus plaguing our patient. Scratching the skin allows the eggs to spread to the fingers and other areas and thus the cycle can begin again. Treatment would consist of either albendazole or pyrantel pamoate, with pyrantel pamoate being preferred due to the fact that it is available OTC and is cheaper. The difficulty comes in the likelihood of reinfection. By the time treatment is administered, the whole family is likely infected and the household is swarming in eggs. Adults also appear to often be asymptomatic with infection. Treatment should consist of the entire family taking medication at one time (a single dose of either drug is effective), and then a second dose of treatment roughly 2 weeks later to remove any reinfection caused by remaining eggs. Furthermore, as much of the linen, underwear, curtains and other areas of the house should be washed within this period as possible. Lastly, the children should be taught the importance of washing their hands and having short nails.


Iosif Davidov

P.S. As for the pronunciation of certain medical words; I too find myself unsure of how to pronounce certain things. For example:

  1. Gilbert’s syndrome – I was told that Dr. Gilbert was French and it is actually pronounced as Zhil-Bear rather than with a hard G and t.
  2. Kaposi’s sarcoma – In the hospital everyone pronounces it as Kuh-po-si, but in the NEJM podcast I heard it pronounced as cap-o-shi. Which one is more accurate?
  3. Pneumocystis jirovecci – I’ve heard most people pronounce jirovecci with a hard juh , but I’ve also heard it pronounced with a yi sound instead of juh and a -tsi instead of a -chi.

I’m sorry if what I have above is confusing especially since I am doing this with an e-mail and cannot pronounce these things in person.

David writes:

Dear Hosts,

The case of the young boy and mother with an itchiness in the anal area which becomes more intense at night sounds like a classic case of pinworm infection by Enterobius vermicularis. This parasite is the most common roundworm infection in the developed world, and ~20% of people (particularly children) in the U.S. may develop this disease at some point in their lives. The itching is caused by the pinworms migrating to the anal region at night in order to lay their eggs in the perianal space.

The child likely caught the pinworms from one or more of his 3 cousins who came to visit – the boy showed no symptoms until after this visit (unless the infectious eggs were transferred from a sushi chef, but the three children visiting seems much more likely). Pinworm eggs are hardy and have an adhesive surface, which can allow eggs laid near the anal region to be easily transferred to an itching fingernail and subsequently onto any other items the infected child may touch (bedsheets, toys, clothing, furniture, etc.) which can explain how the mother caught the infection.

To confirm this diagnosis, doctors should employ the “scotch tape test” – applying a piece of clear adhesive tape to the anal region in order to pick up residual eggs to be viewed under a microscope. Treatment includes medication in the benzimidazole family, including albendazole and mebendazole, which inhibit the microtubule function in adult worms.

Thank you once again for the entertaining and informative podcasts


David P.

Trudy writes:

Dear TWiPpers,

In follow-up to Vincent’s question on TWiP 132 about whether or not one can acquire Paragonimiasis in the U.S., I happened to find the following abstract via Mark Crislip’s puscast:

Although I can’t read the actual paper because it’s behind a paywall, if I correctly recall Crislip’s comments, one has a pretty good chance of acquiring Paragonimiasis (from P. kellicotti) by consuming raw crawfish right here in the U.S.  However, to my recollection, there was no mention of crabs.

While I am writing, I might as well take a guess at this week’s case study.  I am pretty sure that the NYC lady from episode 132 is infected with Enterobius vermicularis, also colloquially known as pinworm.  

The life cycle of this parasite begins with the ingestion of the pinworm eggs, which can be found ALL OVER THE PLACE in houses with small children.  The eggs hatch in the duodenum, where the emerging worms grow and then migrate through the small intestine towards the colon.  Somewhere along the way, the female and male worms mate, the males subsequently die, and are passed with the stool.  The gravid females, however, migrate through the colon towards the rectum, and usually emerge from the anus at night to deposit their eggs around the perianal area.  This is usually what causes the itching sensation.  The reason they need to emerge is because the eggs require oxygen to mature, however, this emergence also causes the mother’s death.  

The itching usually causes small children to scratch themselves, trapping the eggs underneath their fingernails, and propagating the cycle when they put their hands in their mouths.  Yuck!!! Adults are less likely to scratch themselves (especially if they know what is causing the itching!), and even if they do scratch themselves, they are MUCH less likely to stick their hands in their mouths afterwards!!! However, the presence of the eggs all over the house, and the likelihood of the children sticking their hands in the parents’ mouths at times, increases the parents’ chance of becoming infected.  

The pinworm life cycle usually occurs over the course of about a month. Treatment with over-the-counter medications such as pyrantel pamoate, or prescription medications such as mebendazole and albendazole is very effective.  However, since these drugs only kill the actual worms and not the eggs, an effective treatment regimen usually requires a second (or third, or FOURTH) dose at two week intervals to prevent reinfection by adult worms that hatch from any eggs not killed by the first treatment.  

According to “a friend” who recently suffered from this affliction, the movement of the worms is probably THE MOST disgusting sensation that “this friend” has ever sensed! One can diagnose this infection by doing the “scotch tape test”, although why one might want to do that is beyond me.  I would think that the itching on its own would be indicative enough to immediately seek treatment.

Lastly, I think that giving an episode summary at the end of each of the TWiX podcasts is a great idea, because even though I am a loyal fan, my mind does tend to wander sometimes when I listen.    

Thank you for your continued diligence!


Bill writes:

Dear Doctors:

Thank you for the entertaining and educational podcast. I have enjoyed listening to them on my commute in the DC region, where it is an Endor-esque 68 degrees Fahrenheit today.

My guess for the diagnosis is pinworms! As far as my thought process goes, upon hearing the words ‘iching’ and ‘perianal region’. I immediately thought of TWIP #19. Relistening to the episode seems to confirm my diagnosis.

To test this, do a sticky-tape test on the perianal region of all suspected hosts at night. NB: Can use dolls as props, but in that case if the patient speaks Spanish and not English, also add this addendum: “Hazlo a la persona, no a la muñeca”.

As far as advice to give to the patient:

1) Don’t panic! Everybody gets this worm at some point. You can quote Dr. D. on this from TWIP 19: “Nobody is dying from this thing, nobody ever did, and nobody ever will.”

toxacara risk

2) Some people go overboard and become hyper-clean. Avoid this if possible as it can add a lot of stress and may be counterproductive, as unknowingly spreading the eggs all over the room can continue spreading the infection.

3) Do: bathe after waking up, wash your bedclothes regularly, wash your hands regularly, especially after using the bathroom or changing diapers, change your underwear every day, avoid nail biting, and avoid scratching the anal area

4) Treat with mebendazol until itching goes away. Itching may come back. If it does, come get some more mebendazol. At some point, the infection should clear with this strategy.

As an aside, listening to the TWIP on toxacara canis reminded me of this picture I have attached which my little brother (who is an award-winning photographer) took at one point from a beach in Brazil. Enjoy!


Nita writes:


   Hello again TWIP-tastic peeps! This is Nita again, the silly hopeful neurologist-to-be. I am glad to hear that the castrating barnacle was amusing! For this week, our young NYC woman experiencing anal itching for a few weeks puts pinworm on the top of my differential list. Often contracted by children through fecal-oral contamination, female pinworm crawl out of the anus at night and causes itching with egg-laying. The child then scratches and often ingests the eggs at a later timepoint, thus reinfecting the poor victim. The itch-scratch-itch cycle is perpetuated, and the child can easily pass this on to the rest of the family. In our patient, because of frequent contact with children and a son with similar symptoms, pinworm seems to be the most likely cause. Treatment is usually mebendazole.  Another parasitic culprit includes scabies, though it’s kind of unusual.

   Other causes of anal itching include dryness or irritation to the perianal skin. This can result from eczema or rashes (in which different textures like new underwear types or new soaps should be investigated). Allergic reactions could also cause irritation/itchiness, so maybe the sushi can cause this? Dry skin can be a result of using harsh soaps. Increased liquidy bowel movements, diarrhea, or incontinence can also result in itching/irritation.

   There are also other sources of infection, such as candidiasis, yeast infection, or HIV that should be investigated.

   Thanks again for the amazing podcasts!

Caleb writes:

Hello, doctors of TWIP!

I’m a relatively new listener, (a grand total of two episodes) and this is the first time that I’ve e-mailed the show.  I work in law enforcement, and listen to your show while I’m on patrol.  I really enjoy the case studies and as a total layperson, am glad to be able to understand about 40% at best of the science you talk about in the papers you review. Please, keep up the good and entertaining work.

I’ve noticed that the responses to case studies that I’ve heard in the past generally come from people who seem to have reference works to check for parasites, or some kind of expertise in the subject matter.  I have nothing of the sort.  Despite this handicap, I was able to muster up the courage to search Google for “anal itch parasite,” and I think I may have found an answer.  My guess is that your patient has an infection from Enterobius vermicularis, otherwise known more commonly as the pinworm.  The information that I found online says that a pinworm infection causes itching in the anal area as its main symptom, which matches the complaint by the patient.  In addition, pinworm infections are common among young children, especially when there are many in a confined area.  The patient could have been exposed when she hosted the three young relatives 3 months prior, OR in their frequent volunteer work with children. In addition, this seems to be the direction that Dr. Depommier was leaning, when he asks if the patient observed any white things in their feces.  The worms are small and white and can sometimes be observed in the feces of the host.  The pinworm settles and lays eggs in the anal area of the human host, which causes the itching.  The worms can be easily spread, and symptoms can be relatively mild, so it could well be that her son is also infected, since she believes she sees him scratching himself more often than normal, even if he isn’t openly complaining.

Pinworm infection can be diagnosed by what seems to be rather obviously called the “tape test.” Upon waking, the host can place the adhesive side of transparent tape to the anal area, and should be able to collect pinworm eggs, which can be viewed under a microscope. The information I’ve found says that the most common treatments for pinworm infections are the following three prescriptions: mebendazole, albendazole, and pyrantel pamoate, as well as good hand hygiene, as the eggs are often spread by hosts scratching the itchy area, and collecting eggs under their fingernails.  I’m at the mercy of the internet for all of this, so I hope this information is correct.

It’s a  beautiful day in eastern Nebraska, 70 degrees with a light north breeze, low humidity, and barometric pressure at 30.11.  Thanks again for putting so much time into entertaining and educating me and others.  Between TWIP and TWIV, you’ve inspired me to become interested in science in a way that I haven’t been since college.  Have a great day, and keep up the good work,
Caleb (pronounced Kay-lub)


Anthony writes:

Perhaps a Believe It or Not feature might be of interest on TWiP.  A candidate might be the Candiru:

The article is sceptical and that’s good.  That being said — if memory serves me correctly -in a tropical fish publication on Piranhas Candiru attacks are mentioned.  The story was that the indigenous people living on the Amazon only feared the Candiru and the sting ray — not piranhas, electric eels, big cats, or reptiles.

Burroughs mentions the Candiru, too:

On a separate note, Bradbury seems to have Delusional Parasitosis in mind in the Illustrated Man.  In that book, Ray Bradbury has his protagonist say this about his tattoos:

“Sometimes at night I can feel them, the pictures, like ants, crawling on my skin.”

Anthony writes:

Beware of ticks bearing young?

A search in Google books using the keywords tick, viviparous yields

Melophagus ovinus


Johan writes:

Here is a bit of additional information on the mosquitoes/mosquitos “controversy”.

I came across the diversity in spelling in a tweet by Darren Naish.

As I had Parasitic Diseases 6e open on my computer, I searched for both spellings and was slightly surprised to see both variants, so I went to Google Books Ngram Viewer

It appears the usage drifted towards ‘mosquitoes’ starting in the early 1820’s but ‘mosquitos’ has never completely disappeared from usage.

Screen Shot 2017 04 30 at 19.45.11 1140x403———

As to the pronunciation of my name, there are two answers as I have lived 30 years in California and I gave up a long time ago to make Americans people use the Swedish pronunciation. People just don’t hear what they are not expecting.

So, here is the American version followed by the Swedish version.

Anthony writes:

Deterioration of basic components of the anti-predator behavior in fish harboring eye fluke larvae

Monday, 01 May 2017 08:54

TWiP 132 Letters

Written by

Case guesses:

Daniel writes:

Dear Tripartite

I enjoy your podcasts, especially TWIP.  I am very familiar with Dr. Despommier’s background, that of a medical laboratorian. I have been teaching diagnostic microbiology/parasitology/mycology/virology to medical laboratory science (MLS) and medical laboratory technician (MLT) students for over 25 years.  He and Dr. Griffin often give a shout out to all of the hard-working people behind the scene who help clinicians.  Next week, 4/23 – 4/29, we celebrate National Medical Laboratory Professionals Week.  The general public hardly knows we exist, but we supply critical information that a physician can use to make life-saving medical decisions.  And right now, there is a nation-wide shortage of qualified MLS and MLT.  Your listeners can find lots of great information at the American Society for Clinical Laboratory Science website.

Thanks again for the great podcasts. I’m still waiting for TWIF!

BTW: I’ll guess Paragonimus westermani for this week’s case. I introduce this one in my medical parasitology course, so if I get it wrong I will not hear the end of it from my students!

Daniel P deRegnier, MS, MT(ASCP) | Associate Professor | CLS Program Coordinator

Ferris State University | College of Health Professions

Clinical Laboratory Sciences | Big Rapids, MI

David writes:

Dear TWIPanelists,

This case with hemoptysis appears to be straightforward.  It’s hard to imagine that the subject of this case was not worried right away when he coughed up blood.  He must have abstained from visiting a doctor right away out of anxiety for the results, until eventually the duration of the symptoms and his family members’ constant nagging to get professional help won him over.

The culprit is seemingly a lung fluke of the Paragonimus species. Parasitic Diseases 6th edition describes Paragonimus Westermani, but I am quietly considering whether it could have been P Siamensis given the geographical location.  The symptoms match and the eating of crab has likely played a role in becoming infected.

Treatment would be praziquantel or albendazole. I wonder if his postponing his visit has seriously worsened the outcomes, but it cannot have helped.

It is real hot in Nicaragua right now, with temperatures getting near to 100 F – lately I try to “feel” what temperatures in Fahrenheit are like as Vincent recommended in TWIV, as I spent my whole life feeling in Celsius instead.

Thank you so much for your show, it is so much more than just a podcast.

Iosif writes:

Dear Twip Team,

My guess for this case would be paragonimiasis which he most likely obtained from his diet of Som tum. Diagnosis could be made from the findings of eggs within the sputum. While, you could do a BAL in this patient, I think that a sputum would probably be a better choice. Praziquantel for three days would be curative.

In this case, once I had the results from the sputum I probably would not test for TB, but would it be a good idea to get a PPD or a quantiferon gold along with the sputum initially?


Iosif Davidov

Hofstra Northwell SoM

Class of 2018

Nita writes:


    Hello, TWIP-tastic peeps! This is Nita the hopeful neurology MS4. I did a happy little dance when I listened to the last podcast and got brown recluse correct. Didn’t get the correct species, though.

    For this new case with our Thai man who is obsessed with crab som tum, my primary differential is the lung fluke paragonimiasis. P. westermani is common in asia-pacific, and can infect those who consume undercooked crab or crayfish. The larva penetrates the intestines and matures, eventually returning back into the abdominal cavity to penetrate into the diaphragm. Initial signs can include diarrhea, abdominal pain, chest pain, and fatigue. Eventually, when the fluke enters the pleural space, dry cough that can become blood-tinged can occur. The signs can mimic TB, so ruling this out for our patient would be important. Paragonimiasis can enter the cns and eventually cause meningitis. Diagnosis is made though sputum or through feces. Treatment is triclabendazole I believe.

   Other crab-related parasites include angiostronglyus that causes bacterial eosinophilic meningitis. This resolves spontaneously usually, and I don’t think dry cough is usually a classic sign.

    Of course, the sexy guess for this case would be sacculina, the castrating barnacle parasite. It causes behavioral changes in the crab and arrests its reproductive development. It even tunnels its growth into the sexual sac of the crab!! Talk about some parasitic manipulation! I really enjoyed the book This is Your Brain on Parasites, which talked about it. Highly recommended!

Included are my happy face at the meguro museum and a sacculina manifesto! Thanks again for the awesome podcasts!

Brian writes:

Good day ViroMediSite docs! (That’s is my own portmanteau for my favorite podcast hosts!)  I’m back, it’s been a while since my last email for the case study guess and I have been playing catch up on past episodes. In case you have forgotten, I am the guy that likes to listen at work and also tries to type while working. Though I think I am too old for this as I usually make many mistakes, the millennial generation is much better at this. Nonetheless, I am on my smart trying to multitask.

My guess for case 131 is Paragonimiasis caused by P. westermani.  I love this parasite and i have been interested in since reading a case study in my undergraduate parasitology class. I think you even covered the same case from St. Louis involving P. kellicotti from the surrounding areas, some of which I have visited during summer getaways. This parasite is acquired by consuming raw or undercooked crustaceans harboring the infective metacercariae that excyst in the duodenum and then it burrows through the intestine, peritoneal cavity and diaphragm into the lungs where it encapsulates and develops into an adult. I think it takes about 2-3 months to begin egg production.

However, there is usually more symptoms such as, abdominal pain, fever, and weight loss and eosinophilia.

So, that’s my guess, and even though I don’t always write in (if you can call my barely coherent rambling, writing) I do listen to all the TWiX series with this being my favorite. Keep them coming! And just because it can’t be said enough… be nice to Dickson!

Thank you,


Suellen writes:

First, an important note: My name is pronounced SUE ELLEN. I can’t help that my mom decided to shove it together and make it one word. I’m used to it being mispronounced, and I adore you guys and your show, so I am not taking offense, just correcting.

Loved the last episode, even though I once again failed to provide the correct diagnosis. At least I’m consistent! But I’m not happy with my performance thus far, so I’m going to try to get it right this time.

There is not much to go on with our Thai guy, the main symptom is that he’s vomiting blood. Based on the location (Thailand) and the patient’s eating habits, I’m going with Paragonimiasis, or lung flukes. To quote my primary source, the Southern Nevada Health District’s web site:

Humans most commonly become infected by eating raw, undercooked, salted or pickled freshwater crabs or crayfish that contain the parasite inside a cyst. One study found that approximately 17 percent of harvested crabs contained the infectious cysts.

I’m not going to add much to this, since if I got it wrong again, I don’t want to go on and on like I did last week with the wrong diagnosis. My guess could be confirmed by checking for eggs in the patient’s sputum. If it does prove to be Paragonimiasis, then praziquantel seems to be the drug of choice. (An aside, I use praziquantel to help control large and small strongyles in my horses.)

Keep giving us these great podcasts. I listen to all of them, and I really enjoy learning all the cool stuff in them.



David writes:

Dear Hosts,

After being stumped for the last few case studies, I have returned to once again partake in the parasitic puzzler! I believe the man in Thailand suffering from hemoptysis is suffering from a lung fluke in the Paragonimus genus contracted by the consumption of raw crab.

  1. westermani occurs primarily in Asian countries such as Thailand, China, Vietnam, and the Philippines. The CDC website notes that “specialty dishes in which shellfish are consumed raw or prepared only in vinegar, brine, or wine without cooking play a key role in the transmission of paragonimiasis”, and salted crab som tum seems to fit into this category nicely. Treatment for paragonimiasis includes praziquantel given at 75 mg/kg per day with 3 doses taken over 3 days.

The weather has finally been looking up: it is a very pleasant 21 degrees Celsius and mostly cloudy in North Grafton, MA. Once again, thank you for the informative podcasts.


David P.


Anthony writes:

In TWiP #131, there was a brief discussion of arthropod illusions and delusions — the perception / imagination of being bitten by spiders and of things crawling on or in the body.  I’d not thought of it in over thirty years, but I ran across something perhaps similar.  One of the many things that I did in the hope — generally futile — of generating income was to run a residential exterminating business.  I answered one call in nearby North Hudson and was let into a well kept apartment.  The tenant — a non-immigrant in his early 40s — explained that the place was filled with very small flies that he was unable to get rid of.  There were no flies.

With these papers in mind:

A Case of Delusional Parasitosis Associated with Multiple Lesions at the Root of Trigeminal Nerve


Apotemnophilia: a neurological disorder

Might Delusional Parasitosis be a form of Apotemnophilia?

“Self-mutilation can occur in severe cases. The wounds appear in areas accessible to the patient, where they have attempted to excavate the parasites.”

Is Delusional Parasitosis one of “such curious conditions that stand in the hinterland between neurology and psychiatry”?  Curiouser and curiouser indeed!

With an organic basis, alleviation may result from suggestion while the affliction does not.


Thank you.

BTW, here:

they appear not to be updating the TWiP Page.  At a quick glance, the other Pages for your podcasts at Microbeworld look OK.

Anson writes:

Hello TWIP podcasters,

I’ve been studying Haycocknema perplexum for the last two years.   A friend recently shared with me your podcast and I thought I would write in.   

Haycocknema was originally thought to be Trichinella pseudospiralis but subsequent cases showed it to be something completely different (Several papers were published on the initial case calling it T. pseudospiralis). Dave Spratt and Ian Beveridge named it Haycocknema (after Peter Haycock who was the first to dissect out an intact specimen) and perplexum (due to the amorphous cell supporting a gourd-shaped reservoir in the rectal region containing one or more refractile, thick-rimmed globules).

Dave then placed it within the Muspiceoid nematodes due to morphological similarities with other strange nematodes, some which are found in Australian marsupials.  The Muspiceoids were grouped in the Dorylaima nematodes.  There are two families:  Muspiceidae which are found in mice and bats and the Robertdollfusidae found in humans, birds, marsupials and reindeer. Only one muspiceoid sample (cox1 from a bat) was on GenBank. I was able to sequence cox1 and 18s for Haycocknema and it does not group together with the bat sample.  The closest match on genBank has ~90% similarity which can be a problem when you are trying to pinpoint where it fits in on the nematode tree.   More sequences from the different “Muspiceoid” genera are needed to help place them with higher confidence.  Right now Haycocknema falls near the Oxyurids and Rhigonematids (millipede nematodes).   Interestingly these historically have direct or insect-related life cycles. Larval Robertdollfusidae stages have been “identified” in midguts of black flies in Cameroon and in midges of Australia.  

When you look at the known cases from an epidemiological perspective the bush meat hypothesis doesn’t really hold up.   The first patient (a vegetarian botanist in Tasmania) claims to have strayed by eating wallaby once or twice. Two other patients claim to have never eaten native animals. Perhaps the initial diagnosis of T. pseudospiralis helped to fuel the bushmeat hypothesis in subsequent cases?  More genetic evidence from a variety of muspiceoids is needed to help clear it all up.  

Incidentally, the Haycocknema-like nematode found in the Swiss horse is most likely Halicephalobus gingivalis.  Perhaps another interesting candidate for a future podcast?   We just had the first case of Halicephalobus here in Australia a few years ago. The case in the UK with the kidney transplants is quite terrifying.

I created a powerpoint last year for a talk at the ICTMM conference in Brisbane that features both H. perplexum and Halicephalobus if you are interested. I would include it but it is over 10MB.  

Looking forward to hearing more of your future podcasts.


-Anson Koehler

Dr Anson Koehler | Molecular Parasitologist | The University of Melbourne

Johan writes:

Dear parasite fanciers,

Why are there two spellings of mosquito[e]s in Parasitic Diseases 6th Edition?

  • mosquitoes 84 times
  • mosquitos 4 + 1*

Sincerely Yours,



Sollentuna Sweden

*) There is one occurrence of “mosquitos” in the title of “Mosquitos, Malaria, and Man.” by G. Harrison, 1978, but I don’t think that counts.

Deborah writes:

Hello gentlemen,

I am neither a student, doctor, scientist or anyone else related to your world.  I am someone who has recently been diagnosed with Rheumatoid Arthritis.  I’m 47, and was under incredible amounts of stress when my symptoms began.  

Now that I’ve been diagnosed, I’ve found everyone has a treatment for me, and of course, coming to you, I’ve been told about helminth therapy–taking hookworm pills.  I’ve listened to a few podcasts and you seem like you would be the exact people to debate the implications of autoimmune sufferers to begin introducing hookworms into polite society.

What do you think of this?  Have you discussed this before and I’m not seeing the podcast?

Thank you,


p.s.–I found you through pinterest!

Dave the sheep shearer writes:

Good day good Doctors.

Thank you for the interest in my tickology. Further to the babies coming out of the cut in half “tick”. This happened about 15 years ago so pre digital camera (for me) and smart phone so no pics except the ones burned into my memory chips. So here goes. The “tick” was in the area clear of wool on beside the ewe’s udder (yes we have to shear right up to the udder so that the new born labs don’t suck on the wool). It was clearly a tick, fully engorged with tiny legs sticking out on the sides. It was still attached to the ewe. This was not a spider (very short legs sticking straight out from the body) It was in a clear area so when I cut through it I could see that the “babies” came out of the black blood coming from the cut tick.

My wife just reminded me that we took a tick from our dog here at home in southern AB that had live babies in it. This was about 12 years ago

A further note I am currently down with what appears to be Lyme. Likely contacted 3 years ago (when the symptoms started) shearing alpacas in the Okanagan area of BC. This year from one alpaca we took 20 ticks off. 5 black legged deer ticks, 8 what were referred to as Rocky Mountain Spotted( brown tick with a white spot/spots and the rest I couldn’t ID. Wanted to take the zip lock that the owner put the pulled ticks in so I could study the but got vetoed. The pics I took didn’t turn out so I’m sorry but don’t have photo proof .

Dave the shearer in rainy southern AB. Thank you for the wonderful podcast. If I had science teachers like this in school I would have been hooked on science

ps the owner of the alpacas was from Switzerland and had the handiest tick remover that he brought from that country. It looks like a credit card with a slit in one corner. You just put the card against the skin, lining the slit up with the tick. You then slide the card forward until the slit engages the tick. Then you can roll the card over, this action pulls the tick and you can examine the bottom side of the card to make sure you have all the parts of the tick. I’ve tried the “TICK KEY” and it doesn’t work near as well. Can’t remember the name but will try to get the name if you are interested.

Monday, 17 April 2017 08:33

TWiP 131 Letters

Written by

Case guesses

Hannah writes:

Dear TWiP doctors,

Time to embarrass myself with another case guess! Apologies in advance for the long email.

If it really is an arthropod as you implied (and not e.g. a small mammal or snake), I see three possibilities here: 1. a non-venomous arthropod bite that got infected, 2. a venomous arthropod bite/sting, or 3. a venomous arthropod bite/sting that got infected. In the first case, it could be just about anything, although biting flies seem unlikely given the circumstances of the bite. Getting bitten while putting on pyjamas suggests that the arthropod was hiding inside, and that it was defending itself when crushed against skin. A lot of bugs (Hemiptera) have both the mouthparts and temperament to defend themselves in this manner, as do beetles and many many more.

Since I doubt you’d give us a case where the answer is “one of the several million arthropod species that could break your skin when squashed, letting unknown bacteria into the wound”, let’s move on to the a venomous arthropods. One of the many stinging bees, wasps and ants could conceivably cause these symptoms, at least in conjunction with a bacterial infection. Bees and wasps generally don’t hide in pyjamas, however, and while ants might crawl through clothing on their way somewhere else, it still seems unlikely, especially since there was only one bite/sting.

Centipedes are a real possibility. I don’t know what species are found in her region, but their venom can cause intense pain and swelling, and they could conceivably hide in clothing. I don’t think their venom is likely to cause the other symptoms, so this would once again point to some infection.

This brings us to the arachnids, specifically spiders and scorpions. A minority of species have medically important venom that can, all by itself, cause some or all of the symptoms experienced by the patient. If it’s a scorpion, I can’t speculate further – I know next to nothing about that group, though aside from the pain, the description of symptoms in Parasitic Diseases doesn’t seem to match.

Given that the patient is in Peru, the spider genus Phoneutria immediately comes to mind – Brazilian wandering spiders. Despite the common name, some species are also found in Peru. They are known to hide in clothes, but to the best of my knowledge, they are tropical forest spiders, so I wouldn’t expect to find them in the highlands. Much more likely are the genera Latrodectus (widows) and Loxosceles (recluses). Both widows and recluses are shy, non-aggressive spiders that may occasionally find themselves caught up in clothing. Latrodectus are more commonly encountered in their webs, however, and their bites are not necrotic. Any necrosis seen would be from an infection.

Loxosceles, on the other hand, do not weave webs, love to hide in clothing, and their bites are famous for being necrotic. While bites are typically painless, and necrosis usually takes longer than 2 days to develop, it seems like the most likely culprit. Many Loxosceles species can be found in Peru, but L. laeta is the most well-known, and bites from this species can cause both skin lesions and systemic reactions, including renal failure.

Before I sign out, I just want to share this excellent STAT article on delusional parasitosis (also known as Ekbom syndrome): I’d be very surprised if you didn’t have a few listeners who suffer from this awful condition, and it may benefit them to know that they’re not alone and can get help.

Thank you so much for everything you do!



P.S. Dr. Griffin: I’m the one who brought up some of the issues in the arthropods section via your website’s contact form a while back. I apologise if I came across as overly critical or rude – I really do think you guys are doing amazing work, and I’m thrilled that you got some entomologists on board to make this textbook even better!

Carol writes:

She was bitten by a wandering spider, or “banana” spider.


Wink writes:

Dear TWIP Team,

The case of an apparent bite and multi-organ system failure sounds like a dangerous arthropod to me. My guess this week is spider bite. I found the following excerpted information in Wikipedia: “Loxosceles laeta, commonly known as the Chilean Recluse Spider, is generally considered to be one of the most toxic species. It has a very wide range [including Peru] … and has been documented at elevations.”

Wink Weinberg (Atlanta)

John writes:

Hi TWiPerati,

My initial guess in the case of the Peruvian woman with the inguinal insect bite was that she had disturbed a recluse spider (either Loxoceles laeta  and  L. intermedia). That spider lives in South America; bites when disturbed in clothes; can cause lesions and necrosis.

If that is the case, direct treatment options for the woman are limited. Symptoms can be treated to give the body a chance to recover itself.

On the other hand, the family home should be nuked from orbit, it’s the only way to be sure.

However, I am not confident in the diagnosis. The timeframe is extremely short from bite to serious consequences.

The preview of the paper “A Mnemonic Device to Avoid False Diagnoses of Brown Recluse Spider Bites” ( indicates that ulcers would not be expected for a week. Unfortunately, it’s not open access and all I could read was the preview.

I look forward to the answer in the next episode,

Thanks and regards,

John in Limerick, Ireland.

(where it’s 11°C, cloudy with sunny spells)

Nita writes:


Hello, TWIP team. I have recently tuned into the podcast and find it really fascinating! I am a soon graduating medical student going into neurology, but I really like parasites and had been trying to find a good resource to learn about them! This is my first guess submission, so please be kind! I am going to Tokyo soon for my vacation, and I am excited to visit the Meguro parasitological museum! Hope I’m the lucky 14th emailer!

For our 24yo female Peruvian patient, my first instinct of a rapidly progressive necrotizing with black central dot is the brown recluse spider, but maybe that’s my affinity to spiders. After doing a little digging, I did find that the Chilean recluse spider is quite venomous in Peru, and recluse spider bites can cause breakdown of muscles that result in rhabdomyolysis and acute renal failure. However, looks like it doesn’t cause increased WBC count necessarily. Womp womp to this guess from a arachnid fan.

After some digging, such a rapid exacerbation of clinical course as well as the red lesion with a black enter sounds a burrowing sand flea tunga penetrans. The female has a black dot at the read end, and that’s what marks the change. However, I’m not sure of the time course.

Those are my two silly, sexy answers! Doing this in a rush so I didn’t get to think it through. Just jotted down the two “zebras” that popped into my brain.

John writes:


Greetings from Omaha, the city that hosted the very vibrant meeting of the American Society of Parasitologists (ASP) in 2015.

Check out these exciting and fun playing cards ASP made for our conference goodie bags:

My students used them recently to help prepare for the Parasitology Lab practical. It doesn’t get any more vibrant than that!

I haven’t attended an ASTMH meeting, but ASP includes parasites of veterinary importance and others without medical importance such as gregarines and horsehair worms. ASP also addresses the evolutionary ecology of parasites, which may interest the environmental science major from Colby-Sawyer College. Many attendees enjoy the relatively small size of the meeting, which facilitates collegiality and is undergraduate-friendly. Also, no one tries to sell you anything.

My guess this week for the case study is the brown recluse spider, Loxoceles sp.

Although not a parasite, I look forward to incorporating this case study into my Zoology class.

I concluded my Parasitology Lab with the infamous #109 Case Study. I didn’t tell them about the “twist” in the case and they went nuts when they heard the big reveal. Encouragingly, two students guessed the correct parasite (but not host).


Suellen writes:

This one really has me stumped — which I guess isn’t saying much, considering that I’ve not gotten a diagnosis right yet.

This time, I tried to take more time and jump to fewer diagnostic conclusions, but I can’t find a parasitic disease that would manifest so quickly after a bite from a critter in one’s pajamas. My initial guess was cutaneous leishmaniasis, but that takes weeks or months to develop, and the lesions are not just where one is bitten, they are all over the body — but especially on the face and other exposed areas.

Next, I decided to rule out certain vectors. For example, a mosquito is unlikely to get into someone’s pajamas, and even if it did the person is not likely to be able to catch and bottle the mozzie a day later. Fleas fall into the same category, so I am ruling out mozzie-borne illnesses such as malaria and dengue, as well as anything that fleas might carry.

Sand flies? I don’t know much about them, so it’s hard for me to say whether one is likely to end up in pajama bottoms, or to be able to be captured easily, but the diseases that sand flies and other flies carry just don’t come on that quickly after a bite.

Tick-borne parasites? Again, everything I researched would take a week or more to become symptomatic. Same with bacterial diseases, they just don’t show up that quickly. And I ruled out Chagas disease because it also takes a while to show symptoms, and also because I don’t think a reduvid bug is likely to show up in someone’s pants leg. (Also, she has no fever.)

So I came to this: Either (1) the bite did not cause the illness, i.e., the patient was getting sick and just happened to get bitten or stung right before she began to feel really bad, or (2) this is a case of myiasis, where she’s actually got a fly larva of some type living in her skin, and that is what is making her sick.

Now, what I’ve read about myiasis seems to indicate that this is more of a tropical or sub-tropical problem, and our Peruvian patient lives in the arid mountainous region of the country, but I suppose it’s still possible. It also appears that usually you get more than one bite, but maybe our patient reacted quickly enough to avoid being bitten multiple times? And, of course, the scalp and neck are the regions where people most often get bitten . . . so, again, this diagnosis is looking a bit thin. A bite that occurs when you are putting on your pants seems much more like a defensive move on the part of the critter than a “oh, look, I think I’ll lay my eggs here while i’m being suffocated in this pants leg” kind of thing. But if I move along this line of reasoning, I need a critter. The only one I could find that seemed to fit the bill was Dermatobia hominis, the human botfly, which is endemic to the highlands of Central and South America. The problem is that the literature seems to be devoid of any symptoms other than the ones related to the skin — itching, etc. No mention of vomiting or other signs of illness. And I don’t see a botfly seeking out a pants leg when a scalp would be much more handy.

So I am left with the possibility that the bite and the illness are not related, but are simply coincidental, or that this is not a parasitic disease after all, but either poison from the bite of a spider or scorpion, or is just something Dr. Griffin thought up to make us all go crazy rooting around in Google. LOL — nah, he wouldn’t do that to us, would he? But I’m afraid that after all my research I really don’t have a diagnosis, but now that I’ve written all this I’m going to send it anyway, so you will know that I tried my best.

Thanks for keeping me guessing!

Carl writes:

Dear TWIPniks,

I was listening to TWIP 130, and as soon as I heard that the center of the unfortunate woman’s lesion had turned black, I hollered “Brown Recluse!”  Fortunately I was by myself and so did not frighten anyone.  Upon later consultation of Parasitic Diseases Sixth Edition, I discovered that I was wrong, as one would expect of an amateur diagnosis.  But I was close– right genus, wrong species.  This is a case of loxoscelism, caused by the bite of a spider in the genus loxosceles.  Given that the case is in Peru, and the severity of the systemic symptoms, the species is most likely loxosceles laeta.   

It’s sunny and a record-setting 87 Fahrenheit here in Lexington Massachusetts. 


Anthony writes:

Tracking zoonotic pathogens using blood-sucking flies as ‘flying syringes’

Dave writes:

Dear host. I had a very unusual parasitic experience while shearing sheep in the Kamloops area of BC. I’m used to seeing sheep keds but on this occasion I was shearing ewes and beside her udder was a fully engorged tick (not sure what type). I noticed is as I went through it with the shears. Now generally it takes a lot to creep me but this was at the far edge of weird sh#tometer. Out of the cut in half tick came a pile of baby ticks. These were the size of pinheads but fully formed and crawling. Now I hadn’t been doing drugs or drinking or suffering from any other hallucinations that would explain this so even though I have read and heard that ticks don’t give birth to live young what is the other explanation for this.

Thanks for this in advance and sorry that it isn’t human related but most of my parasitic experiences are of the ovine kind

Dave the shearer in sunny southern AB

ps yes Dickson the fishing is great. about 2 hours west of us is the Elk river famous for float fishing

Andrea writes:

Hi Twipitos!

You have probably already seen this one:

Oh boy! Now paradise is off-limits!

It’s 59°F in Seattle with rain of course!

Love the podcast. Please keep it going even though I may never send in a guess. I do enjoy listening to the cases. Even those that creep me out! I now look at all mangos with suspicion.

Monday, 03 April 2017 09:43

TWiP 130 Letters

Written by

Case guesses:

Suellen writes:

Time for me to take another semi-educated guess, this time on what’s ailing the 30-something HIV patient who has presented complaining of diarrhea, vomiting, weight loss, and dehydration. This guy has a lot going on, so it was difficult for an amateur like me to separate what symptoms resulted from his parasitic infection, and which ones from his untreated HIV infection.

After some research, I’m ready to guess that our patient has Cryptosporidium in his intestines, and those little guys are living it up and making his life hell. Crypto commonly causes vomiting, diarrhea, and weight loss, and I even found some special recommendations on the CDC’s web site regarding the elevated risk of this parasite in HIV patients and others with compromised immune systems, who are at higher risk for this parasitic infection.

How did he acquire the parasite? That is much harder for me to say, but I did read that the infection can be passed sexually, so I would suggest that further examination include the man’s partner. How did the partner acquire Crypto? Can’t say.

Keep up the great work, doctors! Love the show, love the cases!

Suellen in Roswell, GA

Wink writes:

Dear TWIP Professors,

I was a small boy in New York City in the 1950s, so one of my heroes was Mickey Mantle. I am proud to have approximately Mantle’s batting average for my TWIP diagnoses! My swing at the man with AIDS wasting and eosinophilia is Cystoisospora belli, previously known as Isospora belli. My diagnostic test of choice is to send a stool sample to Dixon.

Wink Weinberg


Iosif writes:

Dear Twip team,

For my differential I’m finding it difficult as I can’t narrow down my differential to a single diagnosis. So here are my thoughts.

Unlikely Diagnoses: Cyclospora cayetanensis, Cryptosporidium parvum and Giardia lamblia. None of these present with a significant eosinophilia as far as I can tell and I don’t see any risk factors that could lead to them such as consumption of raspberries or contaminated water; however, I am assuming that this infectious agent was either brought in by the patient’s partner or acquired from the nearby area.

More Likely Diagnoses: Cystoisospora Belli, Trichuris trichiura, Strongyloides, Capillaria phillipinensis, Hymenolepis Nana, Paragonimus westermani,

Cystoisospora belli – One of the few protozoans that can lead to eosinophilia and so is on my list. It is transmitted by fecal contaminated food or water.

Trichuris trichiura – Not too high on my list due to the patient not exhibiting many of the classic symptoms like tenesmus. I can’t rule it out completely though.

Strongyloides – I was hoping for some type of rash or cough to help identify this worm. Furthermore, I’d be worried about dissemination in someone as immunocompromised as our patient.

Capillaria phillipinensis – Unlikely because our patient is not in the Philippines.

Hymenolepis Nana – Popularized because of the Colombian patient with the nests of neoplastic cells that were thought to have been derived by this infection. Our patient in not in the Mediterranean so this is again unlikely.

Paragonimus Westermani – Obtained from cray and crabs, neither of which were mentioned in the case. Furthermore, I would expect some type of pulmonary complication.

Overall, I don’t have enough information to say that any of these are definitive. For our patient, the first thing that I would want to do is start some form of IV fluids. He seems to be extremely dehydrated and treating an infection is pointless if he dies before it can be cleared. I would then want to order a stool ova and parasites to see if I could get any information on which parasite is likely and to what medications may be started. Despite all of the parasites listed above, I would still not want to rule out a concurring viral or bacterial infection. I don’t think I would wait for the results before starting antibiotics and antiparasite medications. I think I would start off with albendazole, ivermectin, TMP-SMX, and azithromycin (for MAI). If none of these work, then I would be worried about a fungal disease (maybe GI candidiasis?) Please let me know if my reasoning is flawed.


Iosif Davidov

P.S. When discussing Onchocerca volvulus in the last episode, I remembered that there was a paper that you guys discussed about using imatinib to target filarial ABL like kinases and this could treat the adult filarial worms and thus bypass the 20 year ivermectin treatment. Do you think there is any chance that this could one day be a possibility, or is imatinib just way too profitable/expensive for this to be done?

P.P.S. This case reminds me of a play we recently performed at our school called A Question of Mercy by David Rabe. I don’t know if I am allowed to attach the play because it is supposed to be distributed solely for educational purposes, but if you want to see our performance it is here: School of Medicine Presentation. The play is about a terminally ill AIDS patient in NYC during 1990, suffering terribly (also from diarrhea) and his wish to end his life.

Peter writes:

Greetings TWiP team.

I am currently in Mersin, Turkey, where at time of writing it is dry and sunny with a temperature of 22°C.

The patient in this case study has untreated HIV/AIDS so will be susceptible to numerous opportunistic infections and possible reactivation of latent infections.  The described gastrointestinal symptoms of diarrhoea, vomiting, abdominal pain, weight loss, and dehydration were common in AIDS patients before the widespread use of HAART.

I think that the symptoms indicate a protozoan parasitic infection of the intestines rather than a helminth, though I suppose that co infection is a possibility.

I presume you would want to start the patient on HAART before continuing with the diagnostic testing?

Having done a literature search for ‘Opportunistic parasitic infections in HIV/AIDS patients‘ and listened again to some early episodes of TWiV, I will stick with  protozoan parasites. The most likely. parasites will include Cystoisospora belli, Giardia lamblia, Cryptosporidium parvum, Amoeba, and Microsporidia

Given the lack of pet ownership zoonotic infections are less likely. A lack of foreign travel further limits the likely parasites. I would make a guess at this being a food or water transmitted parasite, further analysis of stool samples, colonoscopy and biopsy will be required to clearly identify the parasite or parasite.

I strongly suspect that the patient is suffering from Cryptosporidiosis due to Cryptosporidium parvum infection.

The CDC has this to say about Cryptosporidiosis:

Nitazoxanide has been FDA-approved for treatment of diarrhea caused by Cryptosporidium in people with healthy immune systems and is available by prescription. However, the effectiveness of nitazoxanide in immunosuppressed individuals is unclear…

For those persons with AIDS, anti-retroviral therapy that improves the immune status will also decrease or eliminate symptoms of cryptosporidiosis. However, even if symptoms disappear, cryptosporidiosis is often not curable and the symptoms may return if the immune status worsens.”

Without antiretroviral treatment cryptosporidiosis has a high mortality rate for AIDS patients and even with antiretroviral treatment total elimination if the infection is unlikely.



Michelle writes:

Dear TWIP Team,

For the case of the HIV positive man with chronic diarrhea and eosinophilia.

If the diarrhea is of infectious origin, it appears that it is due to an opportunistic pathogen which the man is susceptible to due to HIV infection. Although I don’t recall any CD4 cell counts given, I am presuming they are low because the man is not on therapy, has oral thrush, and his partner who is HIV positive remains unaffected.

The more common opportunistic pathogens in the HIV/AIDS patient population in the U.S. that cause diarrhea include Cryptosporidium parvum, Cyclospora sp., Cystoisospora sp., microsporidia, Blastocystis hominis, disseminated MAC, and Cytomegalovirus. There are many other viruses and bacteria that could be involved, the HIV virus itself can also cause enteropathy, and there are possible noninfectious origins like inflammatory bowel disease, but I am guessing there is a parasite involved.

The clue of eosinophilia suggests Cystoisospora belli (in Parasitic diseases: Cytoisospora belli), Dientamoeba fragilis, or Sarcocystis sp, which can all cause diarrhea in AIDS patients. The patient’s symptoms are textbook for C. belli, which is an apicomplexan parasite that infects the intestinal epithelial cells. A person becomes infected by ingesting oocysts typically through ingestion of fecally contaminated water or food. Symptoms in the immunocompromised population include chronic diarrhea that can be extreme, weight loss, weakness and fever. Just as described for this patient.  Diagnosis: The oocysts can be found in stool and are acid fast. Treatment: long course of  trimethoprimsulfamethoxazole.

Dientamoeba fragilis is an intestinal amoeba that is obtained through ingesting cysts that are passed out in human feces. This pathogen can be diagnosed in stained fecal smears, fecal cultures, and PCR diagnostics.  

Sarcocystitis is not strongly associated with HIV patients and thus it is down further on my list. It is another apicomplexan that is obtained by eating undercooked meat. Its life cycle involves an intermediate host. Oocysts are passed in feces of the definitive host and ingested by an intermediate host (often cow or pig). The sporozoites invade tissues undergoing several rounds of reproduction ending their final round in the muscles. Thus, eating the undercooked muscles transmits the parasite to the definitive host.

Thanks for the edutainment,


Carl writes:

Dear TWIPniks,

You mentioned that the ill man in TWIP 129 had a diagnosis that was in “Parasitic Diseases Sixth Edition”.  I figured that meant I had a chance of figuring it out despite my complete lack of medical and biological training.  So last night, I decided to lull myself to sleep by reading all the paragraphs in your book containing the word “diarrhea”.  Fascinating as this was, it was also time-consuming, and I nodded off between the section on Protozoa and the section on Nematodes.  But I think I found a good protozoan diagnosis, so I feel confident in saying that this is a case of Cytoisospora Belli.  (Or it’s some worm from the 400 pages of the book I didn’t read, in which case you can all have a good laugh.)  This is one of three protozoa that cause eosiniphilia, and of those, one of two that causes diarrhea, and of those, the only one found in New York, the only one prominent in immunocompromised patients, and the only one where the diarrhea is bloodless.   

Googling around, it seems like the usual treatment for this would involve, in addition to an antiprotozoal, starting antiretroviral therapy so the patient’s immune system can clean up the mess.  I wonder how this will affect the patient’s decision to forsake such drugs?  I look forward to finding out in your next thrilling episode.

It is a gloomy 40 degrees Fahrenheit here in Lexington Massachusetts as the rain erodes the last piles of winter’s snow.


Gavin writes:

Dear TWIP team,

I’m running way behind on my podcasts, so I need to submit my guess for TWIP 129 ASAP! Could you give us some guidelines on when we should have our guesses in? I work so much better when I have a deadline.

There are a lot of great review articles on diarrheal diseases in HIV-infected patients. It seems that CMV, Cryptosporidium, E. histolytica, etc… are all on the list of usual suspects. However, I’m beginning to suspect that we evolved eosinophils to aid in our differential diagnosis. Cytoisospora belli, Dientamoeba fragilis and Sarcocystis are among the few pathogens which cause diarrhea and eosinophilia.

Sarcocystis seems to be uncommon in the United States, and our patient does not report eating undercooked meat or travel to Asia. D. fragilis is an interesting possibility, but my guess is Cytoisospora belli. As is often the case on TWIP, the proof is in the pudding. Cytoisospora Oocysts can be detected in the stool via autofluorescence. Treatment is with trimethoprim (160 mg) and sulfamethoxazole (800 mg) two to four times a day for 10-14 days. The patient should be started on HAART, with caution given to IRIS. I wouldn’t be surprised if there was a coinfection as well.

Thanks again for such a wonderful podcast! I appreciated Dr. Griffin’s medical school advice, and I’ll keep you posted on where I end up after April 30th.




Elise writes:

Dear TWIP Trifecta,

I am not even close to being caught up on TWIP episodes but I did listen to TWIP 127 and was quite abashed to hear my name mentioned for being truant. I did indeed fall way behind on my listening and researching and writing. I can’t offer any excuses beyond the obvious: “Life gets in the way” one that just feels rather shabby.

I’m now in the process of getting my act together and I promise to write again with diagnoses pronto.

Excuses aside, I have missed very much this parasitic detective work (even though I am prone to diagnostic stumbles).

More soon, soon, very soon.

Best wishes to all

Elise (in lower Manhattan)

Steve writes:

Thought you might like this stop motion public info cartoon of the life cycle, out NHM posted for World Water Day.

All the best,





Steve writes:

Hi Vincent et al,

Just come across this piece on the gruesome-sounding

‘brainworm’. Whether or not the unfortunate moose–executed for ‘blocking a snowmobile trail’ — actually was infected remains to be seen, but this would appear to be another example of a parasite that causes little harm in one species, effecting behavioural changes in another.

Might make an interesting topic for TWiP–maybe even a case history to stump the chumps…

‎”The life cycle of _P. tenuis_ is complex and multi-staged. Adults will lay eggs on the dura mater (the outer layer of the meninges) of the brain or directly into the blood stream of an infected host. The eggs hatch into 1st stage larvae, which travel in the bloodstream to the lungs where they travel up the respiratory tract, are swallowed, and then pass out of the body in the mucus coating of fecal pellets. Gastropods feed on this mucus and ingest the larvae, where they develop into a 2nd and 3rd stage. Infected gastropods may then be accidentally ingested by an herbivore, and the larvae moves from the gastrointestinal tract to the bloodstream, reaching the central nervous system, where they develop to adults and the cycle begins over again. – Mod.PMB”

Amazing we have any wild animals at all really!

All the best,





Thursday, 16 March 2017 09:34

TWiP 129 Letters

Written by

Case guesses:

Peter writes:

Greetings  TWiP team

The patient  is suffering from a generalized muscle weakness that as this is TWiP I will assume is the result of a parasitic infection.

Myopathy refers to a muscle fiber disorder.

This myopathy present as pure motor syndromes without any disturbance of sensory or autonomic function, deep tendon reflexes are preserved.

The high muscle enzyme levels are the result of damaged muscle tissue releasing enzymes into the blood. So whatever the parasite is appears to invade the muscles.

A search of Parasitic Diseases volume six found no mention of myopathy other than cardiomyopathy from Chagas disease.

Well you said it was a rare parasite, it is not even in your textbook!

What could this be, a nematode, something like similar to Trichinella? Maybe a strange Australian Apicomplexan? Onto Google with a search for  Australian  parasitic myopathy.

The search results look encouraging.

The patient  is suffering from Australian parasitic myositis caused by the muspiceoid nematode Haycocknema perplexum

The second item in the search result is the actual case mentioned in TWiP, hers was only the ninth recorded case of Haycocknema perplexum:$FILE/cdi4004g.pdf

Haycocknema perplexum is a rare parasitic nematode infection, believed to be zoonotic in origin though the primary host species is not known. The patient  was treated with albendazole, which was ineffective at preventing continued decline in her muscle strength.  Very little is known about this parasite, more research is needed:



Peter writes:


infection caused by Sarcocystitis species, possibly S. lindemanni

Best wishes




John writes:

TWIP Trio,

Greetings from Omaha, NE where it’s a pleasant 19 degrees Celsius. Having been to Australia (including Darwin) this past summer, I want to submit a guess to case study #128. I stumbled upon this review paper about Nonbacterial Myositis:


The paper reports that Haycocknema perplexum, a nematode, can cause myositis and cases from Australia and Tasmania have been described. Patients experience muscle weakness, eosinophilia and elevated creatine kinase levels. Diagnosis is made by muscle biopsy and treatment is made with albendazole.

I’m teaching Parasitology this semester at Creighton University and I play your Case Studies during lab. The students get a bonus point on their lab quiz if they guess correctly. They’ve been doing fairly well so far. If I guess correctly on this Case Study, I won’t get any bonus points, but I’ll look really good in front of my students 

Sorry I didn’t snag any pictures of parasites while in Australia (except for some fungi), but attached is a picture of the cane toad and Galah bird mentioned on the last episode.

Keep up the good work.


Trudy writes:

Dear TWiPpers,

I am so excited to learn that I won a copy of the 6th Edition of Diagnostic Medical Parasitology!  Thank you!

I am currently on a flight back to Atlanta from Tokyo, where I was fortunate to be able to visit the Meguro Parasitological Museum.  While I did find it interesting, I do regret to say that the museum is disappointingly small and that most of the labels and descriptions are in Japanese, which unfortunately is not part of my trilingual repertoire.  However, admission is free, I picked up a t-shirt, and at least this particular curiosity has been quenched, so there’s that.

Sooo, since I am already writing to you, and since I’m at the beginning of a 12-hour flight, I suppose I should venture a guess at this week’s case study.  I think the 80-year-old lady has Paragonimiasis. This is a mostly food-borne infection caused by the lung fluke Paragonimus westermani, however, domesticated animals may also harbor the fluke and transmit the disease to humans.  That being said, I believe her contact with marsupials to be a red herring.  Nice try, Dr. Griffin!!  Diagnosis would require demonstration of P. westermani eggs in CSF or brain biopsy material.  But because neurological symptoms occur during the chronic phase of disease, CSF examination may not be as helpful as neuroimaging or other diagnostic testing, which may reveal characteristic lesions.  If the lady is indeed infected with P. westermani, she should be treated with praziquantel.  According to the literature, bithional and triclabendazole are also effective, but may require repeat or prolonged therapy.  

Well, there you have it, my uneducated, and probably entirely incorrect guess, but hey!  At least I tried!



Mycheala writes:

Dear TWIP masters

Thank you for all your hard work as always.

For this week’s Parasite guess:

After all the testing mentioned the only test I can think of next is a muscle biopsy!

I’m going to go with the Parasite Haycocknema perplexum. It is a Parasite that has cocked it’s parasitic head in Australia a few times. You mentioned that she recently traveled to Tasmania, which is where this Parasite had been first discovered in 1998.

Also my Dr Google game is very strong and I found her exact case study, here is the link.$FILE/cdi4004g.pdf

Stay parasitic,

Lots of love from

Mycheala, Cork Ireland.

P.s a fun fact, in the link I have provided states that a Haycocknema like nematode has been identified in muscle fibres from a horse imported to Switzerland from Ireland, good to know we’re on the parasitic map haha

Thanks again! Please don’t stop the case studies :3

Fredrik writes:

Hello twip team!

The initial workup seems to point at a myositis rather Than neurologic disease (elevated muscle enzymes, normal neurography etc). Further investigation therefore should be focused on muscle. Autoimmune and paraneoplastic aetiology should be considered. If myoglobin is very elevated hydration may be called for to protect the kidneys.

Some aspects here are less typical for autoinflammatory myositis. I think EMG usually show fibrillation, and eosinophilia is not typical. Physical exam and ANA pattern can give more insight into aetiology. As with all myopathies however muscle biopsy should be considered, which is probably the next important diagnostic measure in this case, possibly guided by MRI to point out active muscle group.

In this case I would expect to see Worms in the muscle (trichinella or taenia of course being to common in this case). A Google search leads me to a couple of Australian case studies where the causative agent turns out to be Haycocknema perplexum, a nematode, that occurs in some of the animals to which the lady had been exposed. This will be my guess.  Mechanism is possibly through skin penetration, though this is not known for sure.

Treatment in those cases was with albendazole, possibly ivermectin could be effective as well. As the treatment for autoimmune myositis is high-dose steroids this patient would fare well from a correct diagnosis (I guess most patients do), since immunosuppression could put the infection in high-speed. However if you do suspect autoinflammatory myositis and treat with steroids, you would monitor CK to evaluate effect and discontinue treatment when it goes up rather than down!

Great case!


Fredrik Bäckström

Resident in Pediatrics at University hospital of Northern Sweden, Umeå

Daniel writes:

Dear crepuscular professors

Despite my ill-informed kava konfusion last time, I’m back for more…

This week’s case was – as promised – mysterious. The 80-year-old Australian lady has clinical and EMG evidence of myopathy. Tests for other causes of eosinophilia and autoimmune myositis are negative. The next investigation should be a muscle biopsy, which (this being TWiP) might reveal some kind of parasite 

Although she has an extensive travel history, her long history of close contact with indigenous wildlife puts her at risk of zoonotic infection. Parasitic causes of myositis include trichinosis, cystericercosis and toxoplasmosis. After googling for parasites, myopathy and Australia I found some interesting case studies of eosinophilic myositis caused by the nematode Haycocknema perplexum.

It’s a long shot, but it fits Daniel’s description of “a rare parasite”. A few cases of human infection with H. perplexum  have been reported in Tasmania and tropical Queensland. The natural host and mode of transmission are unknown. Treatment with albendazole for at least 8 weeks is recommended and recovery may be incomplete. Presumptive use of corticosteroids (standard therapy for polymyositis) led to clinical deterioration and ICU admission in one reported case.

I have to add that I really enjoyed Dickson’s impromptu superhero segment in TWiP 127. Parasitology has such a rich history. More of these, please!

Best wishes



Kadhum writes:

Good afternoon!

The case is Trichinella spiralis!

This parasite induces the formation of a collagen capsule and lead to eosinophilia!

Thank you


Wink writes:

Dear TWIP Professors,

I am going to take a shot at the case of proximal muscle weakness and eosinophilia in the wild animal rehabilitator from tropical Australia. My approach was to search on DuckDuckGo for parasites in echidnas, cockatoos, and marsupials that could infect human muscle. A cockatoo site led me to Sarcocystis and in the 6th Edition of Parasitic Diseases I found this reference:

Fayer, R.; Esposito, D. H.; Dubey, J. P., Human infections with Sarcocystis species. Clin Microbiol Rev 2015, 28 (2), 295-311.

which said that “by ingesting sporocysts from feces-contaminated food or water and the environment; infections have an early phase of development in vascular endothelium, with illness that is difficult to diagnose; clinical signs include fever, headache, and myalgia. Subsequent development of intramuscular cysts is characterized by myositis. Presumptive diagnosis based on travel history to tropical regions, elevated serum enzyme levels, and eosinophilia is confirmed by finding sarcocysts in muscle biopsy specimens.”

Got my fingers crossed!

Wink Weinberg


Nicholas writes:

Scholarly gentlemen,

Thank you for your continued efforts in the production of such an intellectually stimulating podcast.

For this week’s case study involving the 80-year-old Australian wildlife carer, Dr. Griffin provided what I believe is sufficient evidence to arrive at an etiologic diagnosis. I will be the first to admit I had to search through current literature to reach a conclusion, but the following statements outline my thought process along the journey.

The EMG and neurologic exam results suggest myopathic rather than neuropathic origin to the clinically described progressive limb weakness. These findings eliminated the nervous system as the source of this woman’s clinical signs and indicate a myopathic origin, which was further fortified by elevated creatine kinase, an indicator of ongoing muscle damage.

Parasites can result in tissue damage either directly through aberrant tissue migration, or secondary to a robust host inflammatory response targeted against foreign parasitic antigens (i.e., parasitic myositis).

Although there is a laundry list of parasites including cestodes (Echinococcus spp., Spirometra spp. Taenia solium), trematodes (Schistosoma spp.), nematodes (Trichinella spp., Toxocara spp., Hayococknema perplexumOnchocerca volvulusWuchereria bancrofti and Brugia malayi), and protozoa (Toxoplasma gondii,Sarcocystis spp., Trypanosoma cruziLeishmania spp.) documented to cause myositis.  To the best of my knowledge, only Haycocknema perplexum is capable of causing diffuse wasting of major muscle groups. Furthermore, this organism has only been diagnosed in patients from Queensland and Tasmania, consistent with this case study.

Definite diagnosis depends on histopathology with demonstration of the characteristic nematode in the muscle fibers. Treatment with albendazole may improve muscle strength if instituted early enough in the disease process, although recovery is slow and often incomplete due to extensive tissue fibrosis.

Recently, PCR-based sequencing and phylogenetic analysis has revealed this organism to belong to the nematode phylum, positioned between the Oxyurida and Ascaridida orders. Even with this information, much of this nematodes biology (e.g., life cycle and host animal/s) and epidemiology (host range/s and transmission) remains mysterious.

Additional research is needed to allow for implementation of appropriate preventative health strategies, however the inherent rarity of this disease (currently 9 case reports documented in humans) will continue to limit our understanding of Hayococknema perplexum

Keep up the excellent work,

Nick Crossland


Iosif writes:

Dear Twip,

For our 80 yo Australian patient, I would first want a history of treatments that she has already tried. If certain tests or lab values came up with abnormal values before, I would want to take that into account before doing anything. Also, how does she know she is allergic to doxycycline? Is it because she was being treated for Chronic Q fever or lyme disease already? Chronic Q fever can present with pneumonia, hepatitis, or pericarditis and I would do my best to look out for those things. It takes about 2 years of treatment with doxycycline and hydroxychloroquine to treat the infection.

Trichinella is a parasite that actually fits well with her presentation. The eosinophilia and myopathy can be signs of trichinosis. The signs pointing away from this diagnosis are the lack of fever, or lack of mention of a pro-dromal phase with GI symptoms before the parasites extravasate and spread. I would want to know if she has ever eaten undercooked meat anywhere on her travels and I would normally want an ELISA screening for diagnosis, but in this case I would want a muscle biopsy.

The muscle biopsy would also to be to rule out any autoimmune conditions. Dermatomyositis, Polymyositis and Inclusion-Body myositis would need a biopsy to be definitive. I heard no mention of a rash of any sort so dermatomyositis is most likely out, but polymyositis and inlusion-body myositis are definitely part of my differential. Polymyositis generally presents with a proximal symmetrical muscle weakness like our patient and inclusion-body myositis predominantly affects those over 50. The eosinophilia does not fit with either of them and makes me think of eosinophilic granulomatosis with polyangiitis, but once again I don’t see much to suggest that diagnosis such as kidney problems, GI symptoms and most importantly a rash. I would lastly also order many autoimmune markers such as anti-dsDNA, ANA, anti-SCl, anti-CCP, etc. to rule out some autoimmune conditions such as SLE, Scleroderma, and rheumatoid arthritis.

But there is another reason for the muscle biopsy, and that’s because I believe she is infected with Haycocknema perplexum. Dr. Griffin stated that this was a rare parasite and you know what that means… that case reports would be abundant and from these reports I have found at least 3 cases of Haycocknema infection within Queensland Australia and that seems plenty rare for me. The symptoms match up pretty well: chronic myositis, eosinophilia, right geography; the only thing that doesn’t fit very well is that in the case reports the patients all developed some form of dysphagia.

It is not fully known how this infection is obtained or spread and treatment so far has been with several weeks of Albendazole. In terms of outcome, of the 6 cases I found there were 1 death, 2 chronically weakened, and 3 with full/near-full recovery. I hope our patient was able to improve.


Iosif Davidov

P.S. I am a fan of DBZ and I appreciate the meme jokes!

Gavin writes:

Dear TWIP team,

Alright, confession time: I cheated. I was able to find the case report from the team at Cairns Hospital. This is the 9th ever recorded case of myositis caused by the nematode Haycocknema perplexum. That being said, Dr. Griffin was more interested in what tests we would order.

The workup for eosinophilia is extensive, and this diagnosis was far from obvious (at least to me). In the last case I was justified in making the assumption that our young and healthy traveler with exposure and eosinophilia probably had a helminth. That assumption is not necessarily justified in the case of our puggle-loving octogenarian, and I would perform a full laboratory evaluation.

The EMG and symptoms would warrant a muscle biopsy (which clenched the diagnosis in our case). However, it seems to me that you could easily overlook this infection, considering the tissue sample saved for EM did not contain any parasites. Do you think the physicians suspected H. perplexum based on the CK and eosinophilia? I’d be willing to bet that this was yet another case of luck favoring the prepared mind. A faulty diagnosis of polymyositis + prednisone could have killed this patient. Kudos to her physicians!

Thanks for the truly interesting case! I find it perplexing that so little is known of the life cycle and prevalence of this parasite. I’d be willing to bet that subclinical cases are exceedingly common!

I’m in the process of choosing a medical school. Any advice from Dr. Griffin on what factors he thinks are important would be greatly appreciated!



Stuart writes:

Dear Twipsters,

Haycocknema perplexum. Boom.


Gold Coast, Australia

Dr Stuart Aitken MB BS, Dip Ven, FAChSHM

Sexual Health Physician

David writes:

Dear Professors Twip,

I am an Infectious Diseases registrar down in Melbourne, Australia and your podcast has served the dual purpose of keeping me thoroughly engrossed and awake at the wheel along my 150km daily return commute to work as well as preparing me for the DTM&H exam through the LSHTM. Thank you for bringing your case down under and making it irresistible for me to respond.

Clinically, this patient has a chronic myositis, eosinophilia and lives in Queensland. We are told that they have a rare parasite. This instantly introduces the diagnosis of Australian Parasitic Myositis – an uncommon conditon associated with residence in Queensland and caused by the (rare) nematode Haycocknema perplexum – it is usually diagnosed on muscle biopsy and treated with albendazole, expecting some improvement in muscle function. Otherwise, it seems little is known about this organism except that it can complete its entire life-cycle in humans and maybe associated with animal exposure.

However, as a physician, it would be remiss of me to not include a long list of investigations and differential diagnoses. My investigation would initially seek to localise an affected area to target for biopsy, either in muscle or central nervous system. This can be accomplished in the resource rich setting through MRI scanning of brain, spine and affected muscle groups. Biopsy and histology should then reveal the diagnosis. Serology, particularly for parasitic diseases endemic to Australia such as strongyloides, echinococcus and (very rarely, but perhaps in proliferative form) sparganosis/spirometrosis may be helpful to explain this presentation. The travel to Tasmania introduces the interesting prospect of trichinella pseudospiralis, however this should not cause such widespread muscle involvement and would most likely require consumption of a Tasmanian Devil or Eastern Spotted Quoll, both of which I imagine to be unpalatable and difficult to catch.

Thank you for your fascinating and addictive podcasts!

Zac writes:

Hello TWiP Hosts,

As a second-year medical student, with my first board examination in just under three months, I couldn’t help but use test-taking strategy for finding the next step in treatment. History provided us with vital information, the patient handles animals and travels to many tropical areas, thus, making her more susceptible to zoonoses and tropical diseases. The neurologic exam was normal but muscle strength was reduced. This makes disease of the muscle, and not the nerves, the most likely. The tests support this with normal nerve conduction and myopathic changes on EMG. Elevated muscle enzymes also support damage directed toward muscle cells. One side effect of statins is  rhabdomyolysis. No improvement was seen when withdrawing this drug from the patient, meaning that this is probably not the etiology of the muscle weakness. Lastly her eosinophilia and the name of this podcast led me to an initial diagnosis of helminthic myositis. Because there were no ova nor parasites in the stool, the last test needs to find the culprits. The answer to the question is “B,” perform a muscle biopsy.

Thanks again,
Zac from Milwaukee


Becca writes:

Vince, Dick, and Daniel,

Over the past few weeks, I’ve learned so much from your podcasts! I got into parasitism while reading a fiction book called “Peeps” by Scott Westerfield. I loved learning about the parasites in the book so much that I bought “Parasite Rex” by Carl Zimmer, which I’m very glad to have heard you reference on the podcasts.

Currently, I’m a senior in high school, and, come september, I’ll be a freshman at Colby-Sawyer College in New Hampshire studying environmental science. I know it seems a little early to be doing so, but I’m already thinking about grad school. I guess my question for you gentlemen is if there are any graduate schools that you would recommend for a degree in parasitology?

Thanks, and keep doing what you’re doing!


Becca (an inspired youth)

Biomicgirl writes:

Re: canning it

Don’t go anywhere! We’re out there and listening, even when we don’t write in. Thanks for this podcast.

David writes:

Dear Twip wise-guys,

Based on the eosinophilia, I went through the available worms that may cause this, and strongyloides stercoralis seems to be the most realistic option.  The cough would be caused by the parasite traveling through the lungs, diarrhea is a common symptom, the rash manifests where the unfortunate volunteer sat down in faeces. The duration also fits, with Parasitic diseases mentioning on page 245 a typical duration of 6 weeks. The larvae in the stool should confirm this diagnosis, and I expect the patient to have to been cured by either albendazole or ivermectin.

I actually did go through a differential diagnosis, but other options seemed so unlikely and the source of the infection so obvious that I looked no further, and I therefore hope my guess is right.

Let me finish by expressing once more my admiration for your efforts, I know very well that it takes a long time to come up with even mediocre products, and to offer a top class podcast of over an hour (or in Vincent’s case: several of them) on a weekly basis is more than a hobby, it is a mission.

Kind regards from a windy Nicaragua with just 31 C,


Lela writes:

Hello TwiP team,

I have been enjoying the Peace Corps cases. My husband and I were in the Peace Corps in northern South Africa about ten years ago. We were north and east of Thohoyandou ( Luckily the only parasitism we suffered (at least as far as we know) were bot flies. Our host family had several mango trees in the backyard next to the clothesline. I was very happy to return to my washer and dryer and stop ironing all my underwear! I attached a picture of us in our village.

For the current case, I’m making a guess of strongyloidiasis. Although I may be wrong since spell check seems to think this is not a word. These roundworms are transmitted through contaminated soil, thus the direct contact with stool as well as the initial rash and eosinophilia fit with this diagnosis.

Thanks to all of you for your hard work making TwiP such a fabulous podcast!

Adam writes:

Dear Vincent, Dickson and Daniel,

It is cold and wet in Belfast. My guess for this week’s case study is strongyloidiasis which should be remedied by treatment with ivermectin, but only if there are no relevant co-infections.

I have been unable to get a decent diagnosis for the case studies recently and I was particularly stumped by the relevance of cava to the previous case and the hypocrisy of an aid worker living with such expensive tastes. I think I have this week’s though.

I am now the proud owner of a TWiP colour changing mug, and although I’m doubtful of being the fourteenth emailer, I am happy to push someone else into that place.

Many thanks for your work,

Adam Bennett

PhD Student

School of Biological Sciences

Medical Biology Centre

Queen’s University Belfast

Kala writes:

Dear TWIP team,

I love all your podcasts!!!

From not so sunny Ireland:)

From mycheala a long time listener

David writes:

Dear hosts of my favorite podcast(s),

As long as there will be free books filled with biological scientific knowledge I will keep on participating, so keep up the giving mood.  Just heard the latest TWIP, and as it has been from the 14th, I realize I am probably too late.  Still, I should take a chance.

Will also try to find some time for a guess in the eosinophilia case today, sincere greetings from Nicaragua,


Mike writes:

Greetings to the TWIP team!

This letter is to take a chance on the free book, but more importantly, to answer Vincent’s concern that no one was listening. I don’t know who isn’t, but I know that I am. I listen to the podcasts after the fact on my ipod, and usually the cases and contests are old, so there is not much point to guess at the diagnosis when the following episode is already out.

Regardless, keep up the good work.

I am listening to TWIP and TWIV, though not in real time. So this is a letter from the past to the past, I guess.

Best regards to you all.

Mike Martin

General pediatrician, Rochester, NY.

Monday, 06 March 2017 08:57

TWiP 128 Letters

Written by

Case guesses:

Angela writes:

Dear Twipanosome,

Thank you so much for all the wonderful podcasts. I am hoping to be the 14th emailer and win the 6th edition of Diagnostic Medical Parasitology. I probably won’t keep it for myself but I know a medical student who would love to have it.

I am a stay at home mom who used to work as a research scientist/technician for an I. D. doctor. I started listening to TWiP after you discussed a paper my husband co-authored on TWiP 116 and I have now become an avid listener to all the TWiX podcasts. I really appreciate all of them but TWiP is my favorite. My guess for the most recent case presented (the Peace Corps worker in Rwanda) is Strongyloidiasis.



David writes:

To the Hosts with the Most,

I wanted to write in for last week’s cast study, but Episode 127 was published much faster than usual – a surprise and perhaps the reason there were only 2 guesses. I was happy to know my guess of E. histolytica was most likely the cause of the Fiji worker’s symptoms (I had also thought of Echinococcus but it didn’t seem to fit all the symptoms neatly).

My guess for this episode is that the worker in Rwanda has contracted Strongyloides after sitting on feces infected with larvae. The symptoms the man is showing (macropapular rash on this trunk, fatigue, diarrhea) fit this diagnosis, as well as the elevated eosinophilia. The appearance of larvae in the man’s feces are a good indicator that this is a hookworm species and not any other nematode (which typically pass the eggs in the feces).

The infectious larvae in the feces penetrated into the man’s skin on the area where his body came into contact with the feces, leading to the rash. The worms travel to the lungs and penetrate the alveolar space, leading to the man’s cough. From the lungs, the worms travel to the trachea and pharynx, where they are swallowed and eventually reach the small intestine, where they mature into adults. Adult lay eggs that hatch into infectious larvae that can either a) end up in the feces or b) proceed to grow to filariform larvae that penetrate the intestinal mucosa/perianal skin and follow the infective life cycle.

Treatment of strongyloidiasis may be difficult if the disease has disseminated throughout the body, but for uncomplicated cases, the best course of action would be to take Ivermectin (which only works on the adult worms, so multiple doses may be needed).

Thank you once more for the informative podcasts,

David P.

Wink writes:

I love every minute of TWIP, but as a doc, the cases are the best. And cases that can be pursued by deduction are the most fun. Daniel presented a case with 9,000 strong eosinophilia and so I suspect a helminth. This helminth is apparently acquired through skin, can complete its lifecycle (probably a heart/lung passage) in weeks, and produces larvae, not just eggs, in stool. It can be transmitted from non-human stool. According to the 6th edition of Parasitic Diseases, Strongyloides stercoralis meets these criteria. That’s my guess, although I read that S. fuelleborni can be found in some African countries.

Wink Weinberg,

Faithful fan and TWIX booster!

Peter writes:

The signs and symptoms for this case (exposure to faeces, followed by  maculopapular rash, fatigue, cough and diarrhoea, 51% eosinophils  and observation of larva in stool) sounds to me  like classic hookworm disease.

Host responses are triggered by larval invasion of the skin and migration through the circulation to the lungs where the they are coughed up and swallowed, eventually becoming established in the small intestine where adult worms latch onto the intestine wall to feed on blood.

The presence of larva in stool puzzles me, I thought only eggs would be present in stool.

A single dose of albendazole should be effective in curing the infection.

Going back to the mention of kava kava, the British medical authorities seem to think that the risk of liver damage from kava kava is sufficiently high to have banned its import since 2003:

Shelby writes:


I have a few minutes before class starts and thought I’d let you know I’m still listening. I’m not sure if I have a chance at winning the book but it would be nice to have.

I would also like to put in my guess for this weeks case. It seems like the man who sat in feces could have an infection with Strongyloides stercoralis. The rash could be explained by cutaneous larval migrans and by referencing that the patient lives in gorilla country this seems like a good fit as non-human primates serve as reservoir hosts. If I remember correctly you also mentioned eosinophilia and a bout of coughing this could suggest the larvae have migrated from the lungs and now are maturing in the intestines.

I’m not sure about treatment but I worry about hyper infection if the patient becomes immunosuppressed.

Have to run,


Neeraj writes:

Dear Docs,

  First and foremost, thank you for your incessant desire to produce these wonderful podcasts, which I rate as the treasure trove of parasitic knowledge. Given the effort from your side, I understand the disappointment on receiving only two responses to Dr. Griffins’s case study (which is a bit unexpected and I amongst many are guilty of not writing in). Whatever the cause of frugality, let me assure you that the reason you don’t get responses is not because folks don’t listen, but it’s more an outcome of mundane burdens. At my end, I am happy to state that our “Startup” company at sutrovax has finally moved into a bigger facility and helping and coordinating the move has kept me preoccupied. But even then, I made sure that I don’t miss out on the cool TwiP science. It is the single most fun act of self-indulgence (apart from catering to the needs of my 2 year old son) that I perform and not having that would make me very sad.  

Now onto the more relevant and data driven part of my email. For the case presented, the symptoms suggest a case of Schistosomiasis. Given that the volunteer is based in Rwanda, I would like to suggest that amongst the various species of this parasite, its specifically S. mansoni that is the causative agent. The infection can be treated with praziquantel.

And finally, If I am the lucky # 14, I would like to request the copy the book that Dr. Racaniello was kindly giving away. Overall, I would urge that please keep up the great podcast and needless to say, without the case studies, the listening / learning experience would be amiss. I always learn an incredible amount of cool stuff about the world of parasites and the treatment options for the same. The only thing that ever comes between listening and not listening is the sleep at night.

Best regards,


P.S: Sometimes I wish there was a way to cut out the bits about the parasites’ life cycle that Dr Despommier so wonderfully and effortlessly explains. It’s a privilege to listen to you folks and I will continue to be a listener as long as there is a voice from the other side of the table in Columbia University.

Neeraj Kapoor, Ph.D.

Scientist, SutroVax

Gusland writes:


 I just started listening over the past 2 weeks, but I’ve very much enjoyed the 3 Peace Corps cases. This week’s case seems pretty classic for strongyloides: the rash after known contact with feces (as strongyloides does not require a soil maturation phase), rash in the area of contact, and diagnosis by identification of larvae in stool as well as a very high absolute eosinophilia. I was impressed that larvae were found in the stool smear, in my limited experience these are rare and difficult to find. I recall one professor telling us that 7 negative O&Ps were needed to accept a negative result. Other parasites causing similar rash would be hookworm, though larvae in stool would be unusual, or less likely schistosomiasis, though again larvae would not be found in stool as diagnosis is usually by finding eggs in spun urine or in stool. Speed of rash extension can potentially be used to differentiate hookworm from strongyloides prior to O&P being sent. Strongyloides treatment is with ivermectin. I’m only vaguely familiar with the concept of hyperinfection, but if I recall correctly, infection with HTLV1 would put him at higher risk of hyperinfection with strongyloides. There was nothing in his history that indicated that he had been to the Caribbean or east Asia which would have roused my suspicion.

Looking forward to more cases, I’ve been a longtime fan of Bobbi Pritt’s blog “Creepy Dreadful Wonderful Parasites” and I’m happy to get more diagnostic practice from TWIP.

Jeanne writes:

She has hookworms.

Jeff writes:

Hello TWIP Doctors,

I believe the 29 year old peace corp worker has Shistosomiasis.

Haven’t ventured a diagnosis as we were moving our lab from South San Francisco, CA to Foster City, CA.  Never fun…

Please don’t stop the case studies as a lot of time I listen during my commute and get consumed as soon as I get to work so can’t respond.


Jeff Fairman, Ph.D.

Vice President, Research

SutroVax, Inc.

Iosif writes:

Dear Twip Team,


My guess for our final Peace Corp. case is that our patient has either Ancylostoma duodenale or Necator americanus infection. The rash on the back and upper legs is most likely due to the skin penetration by the L3 larvae and the fatigue than came on later is likely due to anemia from blood loss due to these worms. Albendazole or Mebendazole would be enough to treat the worms, but I would also recommend some iron replacement if their anemia became significant enough to cause symptoms.

I included a picture that I found online which I think you guys will find pretty cool. My favorite is the schistosome love embrace in the shape of a heart.

Gavin writes:

Dear TWIP team,

Here is my book contest entry/case guess for the final round of the Peace Corps series (TWIP 127). I’m a long-time listener, but this is my first case guess. I’m taking a semester off to learn some programming before starting medical school next fall. This means that I no longer have an excuse to be a TWIP spectator. The first episode of TWIP was around 11/2009. That means your OG’s (Original Guessers) have had time to finish their training programs and go off in the world like parasitic larvae on agar culture, leaving streaks of TWIP wisdom in their trail. I’m assuming that a new generation will be frantically writing in after hearing VR threaten to CANCEL THE SHOW! How can you even joke about that?!

Anyhow, now to my guess… I remember Dr. Griffin’s mnemonic for eosinophilia: CHINA. Which stands for something, Helminths, something, something…. I was missing Connective tissue disease, Idiopathic hypereosinophilic syndrome, neoplasia, and allergic. I started writing up a long differential diagnosis, but then I found this in the American Journal of Tropical Medicine and Hygiene which helped to narrow my scope.

“The differential diagnosis of eosinophilia is extensive. In industrialized countries, multiple medical conditions need to be considered, among them a variety of malignant, atopic, inflammatory, and endocrine conditions. However, in developing countries, infectious diseases account for the majority of cases of eosinophilia. Because most travelers to developing countries are young and generally healthy and are exposed to the living conditions there, infectious diseases should be at the top of the differential diagnosis list.” (Meltzer, 2008)

It’s also worth noting that anyone my age probably shouted “It’s over 9000!” when given the eosinophil count. This is a popular meme from the 1990’s series Dragon Ball.

Schistosomiasis is a very common cause of eosinophilia among travelers, but the lack of exposure to water gives us an out. Although I did not win the copy of the Manual of Clinical Microbiology from TWiM, I was lucky enough to find a used version. It has a very nice “summary of common nematodes” on pg. 2455. I feel that the presentation fits best with Strongyloides stercoralis and the patient should receive Ivermectin (200ug/kg for 2 days) and be monitored with repeated stool microscopy (alternatively albendazole or thiabendazole).

There are several important points to note about my guess….

– Dr. Despommier seems to feel that this is a very easy case. That being said, these symptoms might overlap a little with Hookworm, especially if the stool samples are improperly handled. I think it would be appropriate to look at the microscopic features of the larvae to make a definitive diagnosis (parasitic diseases pg. 246).

– S. stercoralis is difficult to observe in the stool and may require multiple stool collections over a few days to hit pay dirt. Coproculture using the Agar plate method, Harada-Mori technique, petri dish method, Baerman technique, etc… will increase the sensitivity, but the filariform larva present the risk of infection.

– IgG ELISAs are available, but seem to suffer problems with sensitivity, specificity, and cross-reactivity with other nematode infections. RT-PCR does not appear to be widely available.

-There are animal reservoirs, so the mystery poo need not be of human origin.

-This organism can autoinfect, which can create interesting problems involving disseminated infection, hyperinfection, and bacterial infection. It seems like his eosinophilia is much higher than usual. He is not obviously immunosuppressed and at high risk for hyperinfection (HIV-, no corticosteroids, etc…). However, HTLV-1 is also associated with hyperinfection syndrome. If large numbers of larva are seen in stool, CSF, BAL fluid etc… the patient should be treated for no less than 2 weeks with Ivermectin and albendazole.

Thanks again for all that you do! If I got this case wrong, I feel like I’ve shown enough work to receive at least partial credit.



Chris writes:

Hello TWiPpers,

I was alarmed when you joked (?) about terminating the case studies!  I’ve only written in twice before as I’m usually behind on the podcasts.  So, I submit my guess this week to show support for the case studies – no matter how few guesses you get!

I was heavily influenced by Dickson’s comment that this was an easy case.  So, I looked up symptoms of hookworm.  I already knew it entered the body through the skin and is transmitted in feces.  The CDC’s FAQ about hookworm state that the first symptom is a rash where the worms entered the body.  Bad infections can cause diarrhea and fatigue.  The Merck Manual states that a large number of larvae can cause a cough and eosinophilia.  I assumed by your reaction at the eosinophil count that this was a bad infection, so a large number of larvae could have been present in the patient causing a cough.

While searching, I came across the symptoms of ascariasis, caused by another kind of roundworm.  I thought I was going to have to do a lot more digging, but then I found out that roundworm gets inside people orally and not through the skin.  So, I’ll stick with hookworm.

All the best,

Chris from MA

Hunter writes:

Greetings good sirs!

I’m writing you again from mostly sunny Irvine CA where it’s currently 15.5 degrees out with winds from the SW at 12 MPH.

I wanted to venture a guess for this case study, and to try to give more than just my final answer.

My immediate thought was Cutaneous Larval Migrans (in general), but I wanted to make sure before I sent a mail. I referred to the case description on and the CLM section of Parasitic Diseases 6th edition. Two main things influenced the direction of my search:

1)      The “maculopapular rash”.

  1.       This was what initially made me think of CLM, but I decided to look it up because I wasn’t familiar with the term “maculopapular”.

2)      The fact that there were intestinal symptoms.

  1.       This caused me to look specifically for references to CLM sometimes becoming a full infection when reading the CLM section of your book.

Looking up the maculopapular rash gave me a nice starting list of possible causes, not all of which were pathogens. Since we’re focused on microbes, I’ve left off the non-microbe causes. In addition to them not really falling into the appropriate category for the show, I eliminated each of them for the following reasons (note: CLM was not listed on the wiki page I found).

1)      Scarlet Fever (I had this once 7 or 8 years ago)

  1.       No mention of sore throat, fever or “Strawberry tongue”.

2)      Measles

  1.       No mention of fever.
  2.       Only one of the “three C’s” (coughing) was reported.

3)      Ebola Virus

  1.       While this has the diarrhea mentioned, most of the symptoms were not.

4)      Rubella

  1.       Location of the rash is too limited.
  2.       No mention of fever.
  3.       No mention of conjunctivitis.

5)      Secondary Syphilis

  1.       Most of the symptoms listed on the wiki were not reported for the patient.

6)      Erythrovirus

  1.       The wiki page for this pathogen was sorely lacking in info. I eliminated this one based on the eosinophilia.

7)      Chikungunya

  1.       No mention of the following: fever, joint pain, headache or conjunctivitis.

8)      Zika

  1.       No mention of the following: fever, conjunctivitis, muscle or joint pain.

All of these can also be eliminated (at least as the only infection) as none of them explain the larva in the patient’s stool.

As a result, I felt more confident in my belief that it was CLM, but wanted to get a more specific answer as my understanding of CLM was that it was primarily a skin issue.

Looking in Parasitic Diseases, I found mention that Ancylostoma caninum can cause eosinophilic enteritis rather (or in addition to?) CLM, which made me pretty confident that was the specific species I needed.

Next, I Googled A. caninum directly, primarily looking at the first two results.

The first result was Wikipedia, which indicated that CLM is the more common result of human infection, and that access to the intestines is not available via the skin route, requiring the parasites to be ingested. That seemed to be at odds with your book (based on my understanding of what I read), so I decided to check the second source.

The second result was the CDC page, which also seemed to indicate that CLM was the main result of human infection, but also noted that the larva can migrate to the intestines.

Based on this, my final answer is Cutaneous Larval Migrans caused specifically by Ancylostoma caninum.

Pretty sure this is my first case study guess, so here’s hoping I got it correct.

Hope y’all are having a great day!



QA Analyst 3 : Hearthstone

Blizzard Entertainment

Christina writes:

Dear Vincent, Dickson and Daniel

I have been a regular and faithful TWIP listener since the first episode has been aired. Previously active in research investigating various aspects of leishmania biology, I am now I am more or less confined to the office, creating teaching resources, some of which of ‘parasitic’ nature. I always try to solve your case studies and always intend to write in but never quite get around it. I do feel immensely pleased with myself on the occasions I do get it right. With the imminent threat of loosing the case studies panic set in and I decided to write with my diagnosis, ignoring the gnawing anxiety of potentially getting it embarrassingly wrong.

The Peace Corp volunteer has in all likelihood contracted Strongyloides stercoralis, a soil transmitted helminth. I have spent many hours putting together an image bank for the Diploma in Tropical Medicine and Hygiene and I remember distinctly the L1 larvae of Strongyloides stercoralis being present in the stool of an infected individuals. The larvae are diagnostic for the parasite. Coincidentally, I really like your table of helminths eggs in the sixth edition of Parasitic Diseases, I have  linked this to our course. The table is of course not the only feature of the book I love, it is a great resource. Thanks for making it available. I have of course also linked relevant TWIP episodes to each of the topics in the course! But I digress. The infection is likely to have occurred when the Peace Corp volunteer sat on the ground. Strongyloides also exhibits a free living life cycle, producing infectious larvae and it may be possible that the entire area around the poop the poor chap sat on was contaminated with infectious larvae. Upon penetration through the skin, the larvae migrate into cutaneous blood vessels and are carried to the lungs. Lung passage may be the explanation for the Peace Corp volunteers’ cough. I am not sure about the rash, I thought a rash occurred at the site of larval penetration. Maybe the man was wearing shorts only, which might explain the presence of a rash on his upper back and legs but not on his buttocks. This is pure speculation. In the intestine, the female worms invade bowel tissue, mature and start depositing eggs, which hatch and migrate towards the lumen of the intestines and are passed out. Diarrhoea can be a symptom of Strongyloides infection. High numbers of white blood cells with a large percentage of eosinophils is characteristic also.

Treatment is with ivermectin or albendazole.

I hope this email doesn’t arrive too late, it has taken me ages to listen to the entire episode. I tend to listen in the evenings and frequently fall asleep, having then to find the time point when I nodded off. The falling asleep by the way is a sign of excessive tiredness, not boredom.

The weather is partly cloudy with occasional glimmers of sunlight. The temperature is cold but not unpleasantly so.

All the best.

Dave writes:

Good day My guess for the patient in 127 is Hookworm. Was wavering between hookworm and S. stercoralis because of where he was infected, Rwanda and the presence of monkey who are a reservoir host however, the presence of “fresh” feces would suggest that the S.stercoralis would still be free-living rather than parasitic and the high number of larvae would also point to hookworm.

Thank you for your very informative podcast

Dave the sheep shearer from southern Alberta Canada, where it’s currently 3c and calm. I’m slowly working through your early pods. Up to 24 now and listening to each 2 or 3 times (feeling very parasitic as I’m trying to extract as much knowledge as possible before molting and moving on to the next stage)


Mark writes:

Dear TWiP-erati,

I’ve gotten out of sync for TWiP cases and response dates. It has take a while to get caught up with all the TWiX episodes that congregated in my iPhone after returning from a 15 day cruise and one week vacation. More on that later.

I present my analysis below and plead for mercy from the TWiP-court for being late.

For the case presented in TWiP 126 my guess is a fluke – maybe Clonorchis sinensis. Why? From early shows DDD described fluke are huge and like the host’s liver. My assumption is that the reported cyclone which destroyed his home probably contaminated his drinking water, this infecting the patient. There is a large, 6 cm square area in the patient’s liver. Without biopsy can it be eliminated a colony of fluke?

I wish I had more clinical facts to strengthen this conjecture, or reject it.

Our cruise travelled from Florida, through the Caribbean, northern Colombia, through the Panama Canal, and up the west coast of Costa Rica, Nicaragua, Mexico, and back to Los Angeles. Among our dinner companions were a urologist from Hawaii, and a cardiac nurse from Minnesota. Casual conversation soon turned to zika, etc. Nightly yours truly would regale them with some horrible puns combining parasite or virus names with some type of food to be had onboard.  On a serious note they asked how I, a non-MD, learned so much about parasites. I credited TWiV, TWiP, and TWiM.  Only the urologist listens to podcasts so I hope by now you have a new listener.

I’m attaching a reconstructed/reimagined set list to this email

Today the weather in California was sunny. We’re bracing for another storm and hoping our dams have enough headroom so as not overflow and flood.


Mark in San Jose

PS On tonight’s dog walk I can start TWiP 127 and listen to the case’s solution.

anthrax in the arrugula

ascaris in the avocado

botulism in the broth

candida in the cranberry

dracunculus in the desert

ebola in the eggs

entamoeba in the endive

entero in the eggplant

flukes in the figs

giardia in the grapes

hookworm in the hummus

leishmanias in the lasagna

leptospirosis in the liquor

malaria in the mango

MERS in the meat

naegleria in the nachos

paragonimus in the paste

polio in the peas

reo in the radicchio

rhinovirus in the rice

roundworm in the radish

schistosoma in the scallops

strongyloides in the sake

taenia in the tahini

toxocara in the tuna

trematodes in the tofo

trichinella in the tri-tip

trichiuris in the tarragon

trichomonas  in the tuna

trypanosoma in the tofu

variola in the veal

whipworm in the wheat

yellow fever in the yogurt

ziki in the ziti

Anthony writes:


A local volunteer caring for outdoor cats in Jersey City found this new face at the feeding station the other morning.  You don’t need an upstate cabin to meet raccoons.

BTW, a curious thing about the raccoon roundworms is that they aggressively infest an extremely wide range of animals,  Curiously, felines appear to be immune.


On the topic of wild animals in the not so wild, has Professor Despommier ever seen the deer in Fort Lee Historic Park adjacent to the George Washington Bridge?  I spotted them there at sunset in the winter (around 5 years ago) eating out of the garbage cans in the parking lot.  Whether the deer chose sunset because of natural crepuscular activity or because they learned that the park closed then, I don’t know.

Jacob writes:

Dear Editor,

It is not surprising that leishmanial parasites are influenced by sandfly gut microbiome (and vice-versa). Every organism with a gut is influencing and influenced by its microbiome.

Sincerely yours,



Arie writes:

Dear Professors,

This is the first time I write to you, hoping to be lucky 14, but really also to express my sincere and deep respect to your legendary podcasts. I really love and worship them, they have been some sort of medicine for my soul and that’s not just some fancy exaggeration:

I am a semi-Greek quasi-physicist who left the academic world behind (not that i had any advances to be honest) to take care of my mother after she was diagnosed with tongue cancer back in 2005. She had quite a number of complications, with the incident of completely losing sight from one eye and part of the other due to a candida infection -during a long hospitalization period- being just one of them. She was very brave and optimistic and had adapted to so many challenges and changes due to surgeries and therapies and several infections being carried along the way (klebsiella was another one – antibiotic resistant strains seem to become an increasing issue in hospitals around the world, right?). She passed away 3 years ago, small-cell lung cancer, but not a metastasis from the first one apparently. We had some great times though during this period, humor had always been a good weapon and seeking truth and facts in a calm manner being another one. I started to get more and more interested in all things biology et al, as we faced these adventures and even if I don’t always understand all volumes in all dimensions of your fine analysis, your random podcasts started being a regular sedative for the mind, making me wonder and look up things and even take courses online (proud to have passed virology II on Coursera among them!) Twix became the voice of reason in my world, equally in very dark as also bright times. and well, it’s fascinating science, presented brilliantly by all of you! It kept the mind set and tuned somehow, a stress relief if you want, very amusing and I often managed to fall asleep listening to them- I hope you don’t get that the wrong way of course!

Even if politically, economically, sociologically and probably other ways, things in Greece are kind of deteriorating, there are some advantages being Greek too, naturally: so many words and terminology comes from my native language roots, so I can always smile when you randomly stop for some linguistic puzzles and feel I can still compete understanding that parts with a certain ease! You don’t need to be a polymath for that at least! =)

I know it does not mean really much coming from me and I apologize for the extended letter, but Thank you! from the bottom of my heart, you make this world even more wonderful and more reach.

Sincerely yours, kind regards & God (or universe or whatsoever) speed you (with 9 Beauforts! here today =D )

Jarrett writes:

Hello all,

Just writing for the chance to win the book on clinical parasitology. As an aside, I’ve always been curious about Dr. Griffin’s travels. He seems to travel all the time. When he sees patients in Thailand, Peru and elsewhere, is he doing so as a volunteer, or is there a job out there wherein a tropical medicine specialist wanders the globe, treating the ills of human hosts? Keep up the good work!

Jarrett H.

Austin, Texas

John writes:

Hi TWiP doctors,

Firstly, Vincent’s  comment about “di-hydro-chickenwire” being the active ingredient in kava was beautiful. I guffawed.

Secondly, don’t be disheartened by a lack of responses. Last week’s case was hard (at least for a non-parasitologist).

Thirdly, I’d love a book but a tome like Diagnostic Medical Parasitology would probably be more socially useful going to an actual diagnostician. If I win and a medical professional enters the competition, I would be happy for the TWiP team to give the book to them if I could get a (coveted) TWiP mug instead.

It’s evening, 11 C and drizzling in Limerick.

Thanks and regards,

John in Limerick, Ireland.

Charlie writes:

Hi all,

   I’m hoping I’m lucky fourteen. As an aside, have you all ever thought about doing a TWIP on the parasites of honeybees? I go to veterinary school at Tufts, where we just started the first honeybee medicine class at a vet school in North America (the French are about 4 years ahead of us). Anyway, honeybees are hosts to an array of fascinating parasites, from the aptly named Varroa destructor mite to Nosema, a microsporidian, to Apocephalus borealis, a phorid fly. Hoping to hear a case soon about a 6 month old (bee) with diarrhea (caused by Nosema). Thanks for the great podcast.



Wednesday, 15 February 2017 11:17

TWiP 127 Letters

Written by

Case guesses:

Wink writes:

Dear TWIP Professors,

I think the young Peace Corps worker in Fiji has amebiasis. He might have acquired it sexually or by ingestion. He might be diagnosed by EIA or PCR and should initially receive metronidazole. 8 cm is fairly large and aspiration should at least be considered.

By the way, thanks for answering my question on disseminated strongyloidiasis. If you don’t mind, I have one more part to that question. Would the filariform larvae in someone with the autoinfection cycle be immediately infectious if they found their way to the soil? I am wondering if this was a reproductive advantage to the worm, before coffins and embalming. Perhaps the superinfection syndrome has evolved because of that advantage.

Wink Weinberg


Dan writes:

Dear TWiPsters

I think that the Peace Corps volunteer in Fiji with fever, headache, diarrhea and RUQ pain has an amebic liver abscess. Differential diagnosis would include arboviral infection, biliary sepsis, pyogenic abscess, leptospirosis or acute viral hepatitis. The findings of tender hepatomegaly, raised WBCs, eosinopenia, a modest rise in liver enzymes and the scan appearance are all consistent with hepatic amebiasis. Diaphragmatic irritation can cause a cough.

Positive serology for E. histolytica would support the diagnosis. Cysts may be found in the stool. Treatment is with metronidazole or tinidazole, followed by a luminal amebicide to kill any intestinal cysts and prevent transmission. Aspiration of abscess fluid can confirm the diagnosis but isn’t always necessary.

Although he’s been drinking unfiltered water, he may have acquired this parasite sexually. MSM are a higher-risk group. Apparently Kava has an aphrodisiac dis-inhibitory effect.

(The reference to kava confused me at first – I thought he was drinking the Spanish sparkling wine Cava)

Stay parasitic!


Dan writes:

Dear TWiPanosomes

After Dickson’s comments on TWiP 126, I’m looking forward to hearing his take on the parasitology superhero Sir Ronald Ross.

Many years ago I studied at the Liverpool School of Tropical Medicine, where Ross was celebrated as their first professor of tropical medicine, the first British Nobel laureate, and a talented polymath. When the University of Liverpool opened an institute of infection and global health in 2010, they named the building after him.

It was only after reading Spielman and D’Antonio’s book Mosquito: The Story of Man’s Deadliest Foe and hearing Robert Gwadz on TWiP #28, that I realised that this fascinating character had more of a ‘mixed’ reputation globally.

Best regards


Caleb writes:

Greetings Doctors:

As always I would like to thank you for your wonderful array of podcasts! I look forward every week to listening to new and informative content.

I have two reasons behind my email today.

First off:

I am current the TA of our Medical and Veterinary Entomology course taught to undergraduates here at the University of California Riverside and have been given the privilege of giving two guest lectures to the undergraduate students. I wanted to thank you for the easy access to the pdf of 6th Edition of Parasitic Diseases which gave me a great starting point in developing my lecture on Chagas Disease. I made sure in my lecture to include a link to parasites without borders so any of my students could access your book at will!

Second off:

I heard on the latest episode of TWiV that your entomology contact backed out of producing a podcast on insects. I have a friend and collaborator at the University of Nebraska-Lincoln who is an extension entomologist, who already has an entomology podcast called Arthro-Pod. You might want to get in touch with him about collaborating on a new entomology podcast.

Attached is his contact information:

Johnathan Larson


Caleb Hubbard

Ph.D. Student: Medical and Veterinary Entomology

University of California, Riverside

Monday, 06 February 2017 09:58

TWiP 126 Letters

Written by

Case guesses:

Iosif writes:

Dear Twip hosts.

Since Dr. Griffin stated he wanted a full workup and not just parasites, let’s start with the non-parasites first:

Cholera – This is listed on the CDC as a possible infection in Cameroon; however, our patient’s diarrhea was described as intermittent and cholera is generally a voluminous, watery and non-intermittent diarrhea. I would also expect some symptoms of dehydration or electrolyte disturbance if this has been going on for a few weeks.

E. Coli – Depending on the strain, the diarrhea could be watery or bloody. Most likely she may have EPEC or EIEC. EPEC is also more prevalent in the pediatric population and she may have gotten it from somehow from the school.

Leptospirosis – There are several cases within Cameroon, but there should definitely be more symptoms that what she is presenting with. At the very least I would expect a fever and headache and worst case scenario full blown Weil’s disease.

Salmonella – Another possible cause, but again usually with some more symptoms like fever, nausea or vomiting.

Campylobacter – May cause watery diarrhea or bloody diarrhea. I don’t think the symptoms would last for over a week though in someone not immuno-compromised. I would watch out for Guillain-Barre just in case though.

Adenovirus – Another possibility due to the proximity to children. Also unlikely from the lack of other symptoms such as some rhinorrhea, conjunctivitis or sore throat.

Rotavirus – I assume she has been vaccinated and so this is very low on my list.


Cryptosporidium parvum – Can be obtained from contaminated water. Could result in a diarrhea that last for about 2 weeks that would improve on its own unless the host is immuno-compromised.

Giardi lamblia – Definitely a possibility. I would expect more fatty and foul smelling stools though.

Entamoeba histolytica/dispar – One of the higher diagnosis on the list. Can lead to diarrhea that lasts for weeks to months. Although there may be blood in the stool it wouldn’t be visible to the naked eye and would need to be tested.

Cyclospora Cayetanensis – Especially since she has admitted to eating local fruits and vegetables.

In terms of treatment, I would order a stool ova and parasites be sent and also obtain a CBC to determine if there is any significant blood loss that may be going on or if there is an elevated white count. I would also make sure the patient is hydrated if there is any reason to suspect a significant fluid loss. Lastly, I may order NAAT for several of the parasites like cryptosporidium if the stool O&P is negative and the patient continued to worsen.


Iosif Davidov

Suellen writes:

I am so excited to finally be able to submit my first-ever possible diagnosis! It may be right, it may be wrong, but I don’t care cuz it was fun to research!

This is for the 24-year old Peace Corps worker who has intermittent diarrhea, loose stools, and abdominal discomfort, with no fever or rash.

I actually made a list of possibilities, 10 of them, and then went through them and finally narrowed it down to Ascariasis, caused by Ascaris lumbricoides, a species of roundworm. This is a very common parasite in that part of the world, and people in the early stages of infection often have few or no symptoms. I also picked this because it’s a common disease in children, who contaminate their hands and then stick those little paws in their mouths and infect themselves. As a teacher, our Peace Corps worker is in regular contact with these little infectious disease incubators, and so it seems likely that she may have become infected that way — or, through food or water contaminated with fecal matter.

The sources I checked say that, in the early stages of the infection, the worms may be visible in the stool, so if possible I would try to either get a stool sample or ask our intrepid Peace Corps worker to take a good, close look at that loose stool of hers. In later stages, the worm moves to the lungs and throat, and may cause vomiting or even cause the patient to cough up worms (ugh!), but she’s not at this stage yet.

Treatment? Well, I’m no doctor, but I googled it (just as good, right?) and the common treatments are Albendazole, Ivermectin (which we give our horses to treat worms, too!) , and Mebendazol.

That was fun! And a nice break from my long workday here, where I’m an IT professional (Oracle database administrator) for a big health care company. Even if I’m wrong, it was a nice exercise, and I’ll try again next week.

Thanks so much for TWIP — and all its siblings! Please keep up the good science, we really need it now!


Weather in Alpharetta, GA — sunny and 54 degrees F.

Dan writes:

Dear TWiP Trinity

I’m writing again from London where it’s a dull, wet 6 degrees Celsius. Thanks for an always-entertaining podcast and another fascinating case.

For the 24-year old Peace Corps volunteer with diarrhoea, abdominal discomfort and malaise lasting a few weeks, the differential diagnosis is pretty broad.

Many protozoa including Entamoeba, Giardia, Cryptosporidium and Cyclospora could be causing this. My first thought was Giardia lamblia – a common cause of prolonged diarrhoea in this population. Close contact with children (who could be asymptomatic carriers) and animals are risk factors.

What would I advise if I took the call? Volunteers may have been prescribed ciprofloxacin or azithromycin for ‘standby’ treatment of bacterial diarrhoea (which she may have taken) but this is unlikely to be effective. It’s not urgent, but she would need to have a clinical assessment in a reliable clinic, which may mean taking a trip to the Capital.

Daniel told us that a pathogen was confirmed in the lab. The first-line diagnostic test is stool microscopy – ideally done by a competent lab technician. I’m not sure what level of testing is available – does Yaoundé have a Pasteur Institute? Giardia can be hard to find on microscopy and multiple samples may be necessary. Antigen tests are more sensitive. Diagnosis of Entamoeba histolytica can also be challenging as cysts of non-pathogenic species look identical. ELISA-based adhesin testing (if available) can specifically detect pathogenic E. histolytica.

Cryptosporidium, Cyclospora and other opportunistic protozoa would be possibilities, but they rarely cause persistent symptoms in an immunocompetent host. She may well have a mixed infection after 5 months in the field.

Moving on to helminths, Strongyloides is not a common cause of persistent diarrhoea, but I would test for this if she had eosinophilia. Do the Peace Corps routinely ‘deworm’ with albendazole?

Anyway… these are my initial thoughts based on the limited info provided! As always I look forward to hearing your collective wisdom…

best regards


Steve writes:

Greetings Twipastafarians!

Okay, that was probably stretching the TWIP wordplay a bit far.

I got behind on my TWIP episodes and have only now caught up. I’ll just dive right in to our case study involving our Peace Corp worker in Cameroon.

There are so many possibilities here. I would order stool studies for giardia and cryptosporidium as well as a stool culture and oval and parasite exams.  This should cover most of the usual non-viral suspects.

I am unaware of any viruses that would cause 3 weeks of diarrhea, so I would tend to assume bacterial or parasites to be the culprits.  And, of course, one cannot rule out a mixed infection.

Given the symptoms, I’m inclined toward giardiasis, which presents as intermittent diarrhea in many individuals.  Other possible suspects include ascaris lumbricoides or tapeworms, though in the latter case the lack of proglottids tends to make me rule that out.  Of course, hookworms and other helminths are a possibility, plus a myriad other parasites I’m probably not considering at the moment. I have to confess that I don’t have the time to do a proper deep dive into my free pdf of Parasitic Diseases, sixth edition, this morning so I’m primarily relying on my own memory.

Water contamination is the most likely source. However, since she is teaching young children, contamination from the children is also highly possible. As my wife, a teacher, can attest, children are not notorious for sanitary behaviors.

We just got over a series of storms in the eastern Sierra making this the second wettest January on record. Hopefully this means our drought concerns are over in California.

Best wishes,


Thomas writes:

While listening to your discussion of Naeglaria fowlerii, I looked in both the 5th and 6th versions of Parasitic Diseases and found the word “cribiform”. Alas the word does not exist, although “cribriform” does. I checked Webster’s 3rd International dictionary and used to search the Internet to be sure. They both indicate “cribriform” is correct. I only found this error because I look up words whose meanings I don’t know.

I especially enjoy your episodes where people write in with their guess at the cause of some medical condition. Other than an interest in medicine, especially infectious diseases, and now parasitic diseases, I have no medical background. During my working years I was in the field of intelligence.

As I am almost 80 now, my short term memory is infuriatingly patchy. I am glad Dickson has escaped this condition. Still I try to learn and enjoy what I can.

I bought a new Nikon medical microscope and a lot of histology and histopathology microscope slides. The Youtube has presentations on almost every histology slide I have, so I can look at what they show and see how closely it resembles what I see, as well as learn about the subject of the slide. My microscope does not have “darkfield” or “phase contrast” capabilities but I still can enjoy looking at protists from a nearby pond. When I was in my twenties, I bought a superb interference phase contrast Nikon in Tokyo, where I was stationed with the USAF. I remember how the water was a lovely blue and internal components of the cell were often ruby or gold in color. I haven’t found any such microscopes available currently. Any suggestions? I would spend up to $6,000 for such a microscope.

Thanks again for presenting material that is of interest to me. When I run out of parasites podcasts I have those devoted to microbiology  


Theodore writes:

First time listening I know you guys are a lot smarter but what If the best way to get the vaccine to the liver was putting it to alcohol isn’t alcohol broken down by the hepatocytes.


-Theodore M. Nursing student thinking of becoming a parasitologist

Iosif writes:

Dear Talented Thrilling Tenacious Tantalizing Twip Team,

Once again on behalf of the entire Hofstra Northwell School of Medicine, I express our extreme gratitude for the textbooks. They are being given out right now and here are the first four recipients (I’m the second from the right). Thank you so much!


Iosif Davidov

Wink writes:

Professors of Parasitism (and not parasitic professors!),

I was reading a case similar to one of Daniel’s [CID 2016:63 (1 November) page 1212] and it made me think again about how wonderful evolution can be. Does S. stercoralis sense that its host is dying when going to the autoinfection cycle? And then, does it prepare the proper stage for the soil and finally engineer its host’s return to the soil? Do filariform larvae develop in the human body and will they be infectious in the soil near a buried body? The 

Wink Weinberg

Monday, 23 January 2017 09:13

TWiP 125 Letters

Written by

Case guesses:

Daniel writes:

Dear TWiP superheroes

This time I hope to redeem myself by not mentioning any diseases named after Nazis!

It sounds like the 28-year old man from Thailand with periodic high fever and chills has malaria, although he has an atypical pattern of fever. The clinical and lab findings (hepatosplenomegaly, jaundice, low platelets, anemia, infected red cells) all support this diagnosis.

The severity of his illness is consistent with Plasmodium falciparum… but the blood film appears to show P. malariae, with ‘band form’ trophozoites in normal-sized red cells. P. malariae causes a milder, chronic illness.

So… the probable diagnosis in this case is P. knowlesi (‘monkey malaria’) a zoonotic infection found in the jungles of SE Asia. It is morphologically similar to P. malariae on microscopy. P. knowlesi has a shorter life cycle and can cause daily spikes of fever and a rapid increase in parasite count. PCR confirms the diagnosis.

As he has >2% parasitemia, hypotension and renal failure, the treatment of choice would be intravenous artesunate or quinine if this is not available.

What was the outcome?

best wishes, Dan

(London, UK)

Wink writes:

My guess for the case of the Thai logger is P. knowlesi because of the geographic location, presumed proximity to monkeys, band forms and high parasitemia. The organomegaly suggests chronic malaria, so I wonder if he has more than one parasite or “ticks and fleas,” as they say.

Wink Weinberg

David writes:

Dear Hosts,

I believe the young man in Bangkok has contracted a case of malaria, particularly malaria spurned by the species Plasmodium vivax. P. vivax is particularly dominant in areas of Asia such as Myanmar and Thailand. This also happens to be the particular species that causes splenomegaly, and has been found to rupture from erythrocytes within 48 hours of merozoite invasion, which may fit the man’s 2-day onset of chills. According to the 6th Edition of Parasitic Diseases, P. vivax infection typically causes around 2% infection in RBCs, but in this particular case, the man may have a higher parasite load due to the development of hepatosplenomegaly and the high number of mosquitos bites garnered while sleeping outside. The man’s other symptoms (jaundice, dark urine, difficulty breathing) are indicative of other malarial infections, so it is possible that since there is a higher RBC infection rate and multiple band forms present, he may have another species of malaria infecting him, particularly P. malariae (which causes “big spleen disease” in tropical regions.) Treatment includes antimalarials such as chloroquine, mefloquine, or artemisinin-based treatment.

Once again, thank you for the informative podcasts.


David P.

Mohammed writes:

Good evening TWIP trio from cold, dark, foggy London, UK.

I last sent in an answer to a case study a couple of months ago while completing the Diploma in Tropical Medicine and Hygiene. I found your podcasts to be an invaluable source of information, and enjoyment, while studying parasitology for my exams, and having finished the course, I am trying my best not to let the knowledge I’ve gained slip. With that in mind, here is my answer for the most recent case – the gentleman from Thailand with fever and a high parasitaemia with band-forms visible on the film.

When Dr Griffin first mentioned band-forms, my immediate thought went to Plasmodium malariae, the trophozoite of which classically assumes a band-form shape within infected red blood cells. However, there were a couple of features of the case that challenged this diagnosis.

Firstly, the high parasite count in this patient is not something you would typically expect with P. malariae, which preferentially infects older (hence smaller) RBCs and wouldn’t typically cause a parasitaemia greater than a few percent.

Secondly, the daily (or quotidien) nature of the fever, while being perhaps a slightly soft sign, again is not typical of P. malariae, in which fevers classically occur every 72 hours. I’m sure you guys have discussed the ridiculous naming system for fever frequency with malaria before – a fever occurring  every 3 days is called quartern!

Thirdly, you had an interesting discussion about this patients job, which would put him outside during the day in forested areas. Interestingly, I believe anopheles mosquitos in this part of the world are often day-biting, perhaps mitigating any effect of the patient not sleeping under a net. More importantly, his work might bring him to the vicinity of macaques in the forest. These happen to be the reservoir host for Plamsodium knowlesii, which is my guess for the case study.

This zoonotic parastic infection is associated with morphology similar to P. malariae but causes daily fevers and can have very high levels of parasitaemia, which in turn can make people very sick. It is also geographically limited to South-east Asia, in particular Malaysia and Borneo, but I assume it has made it as far as Thailand.

Treatment would be as per other severe malarial infections, with IV Artesunate and supportive care until the patient has improved, and then oral Artemisinin combination therapy to complete treatment.

He could also probably do with some advice to wear long-sleeved clothing when working outside – perhaps someone could come up with insecticide-treated shirts and trousers for these guys to wear???

Anyway, I hope the patient recovered well and I look forward to hearing the outcome in the next podcast.

Happy new year to all of you, and please keep up the great work.


Neeraj writes:

Dear TWiPonderers,

This is Neeraj from gloomy, murky and insanely wet Bay Area in California. Don’t get me wrong, I am totally in for all the rain we are getting to help us make the deficit for the looming drought, but there’s just something about grey skies. I just HATE them.

Apart from this, I am glad that TwiP released a podcast early in the year and based on Dr Griffin’s presentation of the symptoms for the latest case for the male at the Burma Thai border, I would like to suggest that the man is suffering from malaria. All the physiological symptoms (like shaking chills and no diarrhea) along with the low glucose and RBC infections (a whopping 5-10%), point towards an advanced infection of malaria. I think the prescribed course of medication would be artemisinin coupled with antibiotics?

On a different note, I was recently reading about toxoplasma and while browsing the website for journal cell, I came across an interesting paper (please find attached). In this manuscript, The authors describe an intrinsically disordered protein (IDP) namely GRA24 and show how it activates a canonical MAP kinase pathway to maintain infectivity. Personally, I have always loved working with proteins as I think there is something very definitive about the in vitro experiments one can do with purified components. Obviously it’s a reductionist point of view (like most science), but it can give one the kind of insights that can be fascinating (at least that’s the way I feel). For example, this paper has a figure showing the structure of a complex between the IDP and p38 MAPK, solved using SAXS. (Dr Racaniello I was listening to the recent episode on TWiM about the bacterial calliper protein so thought you might be interested in seeing the diverse roles SAXS technique can serve. Although I still think the resolution on the order of Angstrom scale presented in that manuscript was a stretch).

In any case, thanks as always for a wonderful podcast. It’s always a pleasure and a great learning experience to listen to the esteemed group of TWiPologists, both conducting and listening to the podcasts. I can’t remember a single episode from which I never learnt plentiful. Please keep the ball rolling and here’s to an infectiously rewarding 2017 of scientific discoveries.



Neeraj Kapoor, Ph.D.

Scientist, SutroVax

South San Francisco

Toni writes:

Dear parasitologists:

As always, here is another very interesting case.

The clinical picture is that of a young patient with a fever and dark urine. This last suggests coluria, being hyperbilirubinemia one possible cause. In the clinical practice, among the long list of possible infectious causes of fever in tropical countries one must always consider typhoid fever and blood cultures should be taken. The symptoms, the hyperbilirubinemia and the fact that our patient had frequent contacts with animals also suggest leptospirosis, which is highly prevalent in tropical countries.  And of course, highly endemic in SE Asian countries, dengue fever is always something to think of.

Said that, and assuming this is a case of HUMAN infection (not penguins this time!), the case strongly points to human malaria. The band forms are typical from both Plasmodium malariae and Plasmodium knowlesi. The first one is rare even in endemic countries. The second is recognized today as an emerging infection and in endemic countries, such as Malaysia may be the most frequently diagnosed species. Microscopy cannot really tell the difference between both species, so PCR test is mandatory. P.knowlesi causes higher levels of parasitemia, and the prognosis is a bit poorer than that of P.malariae. This species is a zoonosis, and different monkey species are considered the natural hosts. Deforestation is leading to an increase in the incidence, since it brings human beings, monkeys and anopheline mosquitos into close contact. So, in the former scenario the parasite follows a cycle monkey-mosquito-monkey, but in the new one, the cycles has changed to a monkey-mosquito-human or simply human-mosquito-human as is the case for the other four human species. Our patient works in the timber industry, making the contact with the parasite much more likely. Otherwise, one cannot rule out a mixed infection by different Plasmodium species, and again PCR could help in the diagnosis.

So, my best guess this is a case of a P.knowlesi infection or a mixed infection involving in any case P.knowlesi.

P.S. It seems to me very interesting to add that P.knowlesi is not a new discovered species. In fact, it was once used by Dr. Julius Wagner Jauregg as a treatment for patients with neurosyphilis with some success. The idea was to generate fever, as Treponema pallidum is a thermolabile microorganism. The parasite was transmitted intravenously from one patient to the next. In fact, we could see Dr Wagner as A VECTOR, a “human anopheline”. Unluckily, after some passages between patients, the resultant strain gained in virulence, complications began to occur, and the treatment had to be stopped. For theses achievements, in 1927, Dr. Julius Wagner Jauregg received for this work the Nobel Prize in Medicine, being actually the first psychiatrist to win the Nobel Prize.

Thank you very much. I anxiously wait for the next episode.

Iosif writes:

Dear Twipettes,

My guess as to the diagnosis of our Thai patient would be malaria. There aren’t many things that infect RBCs and since babesia is limited to the US, I believe that malaria is a safe bet. Plasmodium falciparum is the most common species to cause infection in Thailand and there is a good amount of resistance found within the country. This combined with the fact that 5-10% of RBCs are infected cause me to worry greatly for our patient. On Uptodate, there is a criteria for diagnosing someone with severe malaria. In our patient; if the glucose is less than 40 mg/dl, parasitemia > 10%, H&H < 7g/dl/20% respectively, or any episode of major bleeding would be enough to categorize this as severe. It is a good thing he was able to get to a hospital as soon as he did. I would start artesunate treatment as soon as possible, along with IV fluids with glucose. Depending on how bad his anemia is, I would consider packed RBC transfusion. I hope that this patient was able to get better.


Iosif Davidov

Hofstra Northwell SOM

Class of 2018

Ryan and Perrin write:

Dear Doctors,

We’re two students writing in for the first time from Ontario, where we’re currently experiencing mild January temperatures in the 2 degree-C range. We’ve been listening for a while and thought it was about time to take a crack at a case.

In regards to the case discussed in episode 124: Given geographical location, quotidian fever, spleen and liver involvement, as well as the risk factor of sleeping outdoors at night, we guess that the patient is suffering from Malaria. Based on the information, we think P. falciparum is the most likely culprit, although 5-10% infected RBCs seems high, this could be explained by increased exposure to hungry mosquitos or perhaps an immunocompromised status. Given his age and ongoing residence in this area, we would expect a higher degree of immunity, and so suspect an underlying condition.  P. vivax also seems a potential organism, however has lower prevalence in this area, and additionally only infects reticulocytes and so rarely would reach this level of parasitemia. We expect to see infected erythrocytes of normal size. We suspect that this is a new infection, not a recrudescence (as which could be seen with vivax).

We suggest treatment with Atovaquone-proguanil or doxycycline

Looking forward to seeing if we are correct in our first TWiP diagnosis.

Ryan and Perryn


Connor writes:

Hello TWiProfessors,

I am a longing term listener of TWiX, started with TWiV and then found TWiP.

It is a warm 33°C here in Muang (city) Ubon Ratchathani, Thailand. Where I am a temporary government employee at the Office of Disease Prevention and Control.  

Shoutout to my professors: Dr. Gerald Esch and Dr. Raymond Kuhn at Wake Forest and Dr. Mario Grijalva at Ohio University/Pontifica Universidad Catholica de Ecuador. They are all wonderful educators that have surely changed many lives for the better.

Ok down to business.

My first guess ever.

For a Pt.  presenting with raised rash that some might describe as serpiginous, has spent time in Western Dominican Republic, and walked around without shoes I would guess CLM. After ruling out S. stercoralis, due to lack of pain in lungs and/or belly. Not sure if it is A. braziliense, A. caninum, or another species.  

Either way Tx. Outside US: 10% thiabendazole cream twice daily for 14 days. Inside US or if widespread lessons: oral Ivermectin (0.2 mg/kg single dose), albendazole (400mg daily for 7 days), or mebendazole (100-200mg daily for 5 days).

Thank you all for this wonderful gift and Happy New Year to you and yours.


Wake Forest University 2015

Biology Major

Religious Studies Minor

Frank writes:

Dear Doktor Doktor Doktors,

In TWIP #124 (28:00) you commented on the price disparity of Albendazole between the US and the DR.  While Dr. Griffin pointed to the freedom of the US capitalist market and the need for balance between profits and public health, other comments mentioned the expense of development and clinical trial failures. TWIP is so wonderfully authoritative that I worry about these off-expertise comments on the beliefs of your listeners.

Research & clinical trial costs are often used to justify high pricing.  A cursory review of pharmaceutical company income statements show that R&D is around half of marketing expenses.  As one example, Pfizer’s 2015 income statement shows Selling, Informational and Administrative (SIA) expenses to be 30% of sales while R&D is only 15.7% while still making an impressive 14% after tax profit.  (average manufacturing sector profits are 5%)  Even if the marketing portion of SIA is half the total, R&D is not the necessary reason for high prices.

Many may discount this calculation so to Dr. Griffin’s point, I would direct your listeners to an alternative R&D funding system proposed by Bucknell economist, Dean Baker  He proposes federal funding and patent ownership allowing free market competition for drug manufacture and pricing.  He points out that patents are a means of taxing the public to support research and innovation (  (Another example: According to the Kaiser Family Foundation, administrative costs in Medicare are only about 2 percent of operating expenditures. Defenders of the insurance industry estimate administrative costs as 17 percent of revenue.

As always, thanks for taking the time to provide the greatest public education shows ever.  The world needs your format and style to be more infectious and spread to all areas of science.

Best Regards,


Steve writes:

Hi Vincent, Dickson and Daniel,

Good to find you back in my inbox so quickly into the New Year (And to see that your stable at has enlarged too!). And a belated Happy 1000000th to Vincent too!

Your brief mention of parasites that ‘hoarders’ ‎might get from an excess of pets, reminded me that I saw this piece on raccoon ascaris in Promed Mail the other day.

Looks to be a particularly nasty one to catch when it does get into humans. Your further mention of someone checking the parks for parasites from dogs and cats‎, made me think that in NY they might be finding the raccoon parasites too, and that people ought to be made aware of the risks of encouraging them to become too domesticated.

All the best,




Where it seems to have warmed up after a few sub zero days, and I can now hear myself think above the central heating pump!

Massive poo writes:

hello TWERPS

i have no formal scientific or medical training, but have managed a home lab for some years studying micro organisms along the following lines:

i have fungus in the bathroom

fungus in my bed

fungus in the kitchen

and fungus on my head

i got a parasite for christmas

and keep it quite well fed

it rides around inside my brain

on a neurotoxic sled

i think it makes me rhyme all day

but perhaps now it is died

(are parasites all criminals?

..they spend a lot of time inside!

err, well on with next weeks case study

as a lay person, i think dr griffins case next week will have the red herring of a do-gooder that doesn’t wear shoes,

but in this case the victim will be attacked by a face eating spider, or to use the latin name, faccio spidercium.

the life cycle of the face eating spider begins and ends with a mature female laden with eggs, who hides under peoples beds at night and giggles

until it can hear the sound of snoring, this triggers the spider to climb onto the bed and jump on the victims face and squirt the eggs into the rosy part of the cheek.

this serves two functions of masking any rash or soreness, and the closeness of blood vessels to the surface of the skin and injection site affords an easy meal for the hatching larvae

the circadium rhythms of the host (usual a mature male of advancing years, say dixon) trigger the larvae to errupt through the skin and crawl to the nearest ear duct or nasal canal where they proceed to masquerade as nose hairs and ear hairs, and feast on bogies and ear wax, the female young do this until pregnant and then scarper under the bed again to repeat the process

i hope that it is not too dispiriting to find a lay person and virtual novice can solve these problems without any research,

but as darwin once said “if you need to study, you’re doing it wrong”

best wishes and kind regards for all your fun and capers

i suppose you have added to the sum of human knowledge in a right prodigious way too, many congrats

Dave writes:

Hosts with the mosts

Sorry that this is a question from the beginning of the show buuuuut. Just started listening at 119 and now working from the start to catch up.

It was mentioned that a team of explorers heading for the north pole by balloon went down and had to live on Polar Bear meat to survive. You mentioned that when the explorers bodies were found they were infested with Trichinella from eating polar bear meat. My question is, do fish carry Trichinella. My reasoning is that the mainstay of polar bears are seals and the main stay of seals is fish therefore the only (not quite but almost) source of Trichinella for the polar bears would be fish. Couldn’t find answer online but didn’t check very far.

Dave the sheep shearer in southern Alberta Canada where it is +2c and the chinook wind has died down

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