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Wednesday, 17 January 2018 18:06

TWiP 145 Letters

Written by

Case guesses:

Mike in Oregon writes:

Hello gentlemen,

My guess for case 144 is Anisakiasis..Since I am not a doctor or even close, I will quote the CDC...

Thursday, 14 December 2017 16:11

TWiP 144 Letters

Written by

Dear TWIP Professors,

If you search The Text for cornea, you find Onchocerca, Trichinella and Thelazia. However, my guess will be different and I’ll probably be wrong, but I’ve gotten used to that. This case was from a while ago, and long ago I participated in some field clinics in Panama...

Tuesday, 12 December 2017 13:47

TWiP 143 Letters

Written by

Lucian writes:

Dear TWiP-masters,

Which parasite is it? Based on the morphology, I believe the patient had whipworm. The narrow end followed by a larger, coiled end is indicative of whipworm, and the length is within the normal range. In addition, the adults live in the large intestine, where a colonoscopy could discover them...

Monday, 20 November 2017 18:52

TWiP 142 Letters

Written by

I’m not a professional in any way, just a curious science enthusiast, so I’ll keep my guess general and brief.

1) Rhino should clear up on its own

2) Salmonella could account for most of not all symptoms, antibiotics seemed to clear it up...

Wednesday, 18 October 2017 14:53

TWiP 140 Letters

Written by

Anthony writes:

I’d not heard of knockout rats before the TWiP 139 paper discussion.  

As luck would have it, last Saturday I happened upon a December 2009 issue of Science.  On the back cover there’s an ad for knockout rats.  (Image attached.)..

Saturday, 12 August 2017 19:25

TWiP 137 Letters

Written by

David writes:

Dear Hosts,

I believe the young Muslim in India has contracted a rarely reported case of isolated cysticercosis (from the prok tapeworm Taenia solium) of the sternocleidomastoid muscle.

Wednesday, 12 July 2017 11:12

TWiP 136 Letters

Written by

Case guesses:

Mike writes:

Hi guys

I think the man has Guinea worm disease (dracunculiasis) from drinking contaminated water somewhere in Africa. The adult worm which is under his skin has probably released its larvae into the water the man was using to soothe his painful foot. These larvae would normally be eaten by water fleas, people drink water containing the fleas and the cycle continues. It may take up to a year for the larvae to become full adults.  There are no drugs to treat the disease and the only option I am aware of is to slowly pull the worm out through the wound and wrap it around something like gauze or a stick. It may take a week or two to get the whole worm out. CDC reported that in 2016 only four countries had local cases: Chad, Ethiopia, Mali, and South Sudan and that the number of cases have gone from 3.5 million per year in 1986 to 25 in 2016. Wow. It’s through the efforts of people like Jimmy Carter and the Carter Center that have made this disease well known by airing TV ads in the USA and I hope he lives long enough to see it eradicated.

I hope this improves my dismal record for answering case studies.

Mike in Oregon

Richard writes:

Dear TWIP titans,

Based on the torrents of praise that issue from emailing listeners from around the globe, I may well be alone in my lack of enthusiasm for the regular feature of clinical case studies featured on your most excellent podcast. While I truly appreciate its value to listening clinicians in the management parasitic disease. While I hold the kind Dr Griffin in the very highest esteem, I find that the time lavished on the case studies gouges too deeply into the exploration of nonclinical parasitism that enthralled listeners in the Golden Age of TWIP. Am I the only TWIP addict who is curious about the protostrongylid lungworm, Umingmaksrongylus pallikuuhkensis, that troubles the proud muskox? Is no one else fascinated by Melampyrum arvense, a hemiparasitic flower whose defensive glycoside protects mice against liver damage by carbon tetrachloride? And what of Myxobolus cerebralis, that appears to cause the dreaded whirling disease in brook trout, and whose spores resemble an asterix? I may have missed one or more of these in the unheard archives, but by and large these natural wonders are passing us by, obscured in the glare of people’s parasitic pestilences. I hope that at some time in the future, general economic development will render the prevalence of parasitic disease low enough for clinical focus to be safely relegated to occasional attention.  

Having gotten this long-simmering gripe off my chest, and hoping to be win a copy of your intriguing tome, I would like to offer my very first guess. I believe the Queens resident who enriched my country upon his arrival from Africa was accompanied by Dracunculus medinensis, AKA Guinea worm. When he soaked his foot, the little lady thought her opportunity had come at last, to release her eggs into cool open water. She began her unexpectedly long journey when, as a larva, she was eaten by a tiny crustacean of the genus Cyclops. Her host was ingested in turn by our new neighbour, where she met her mate. Tragically widowed, she made her way to the skin and bided her time. A year later, she prepared her exit blister, and the rest is history.

Home care will entail gently drawing her out of the wound over a period of up to several days, winding her long body around a cylinder, a little at a time. Asclepius would approve.

Mark writes:

Dear D-G-R Trio,

I’m writing this on the first full day of Summer 2017 where I’m 1/3-rd of a mile from the Pacific Ocean on California’s Central Coast. I’m avoiding the double and triple digit heat wave currently scorching inland California.

For long-time listeners this case was a “no-brainer” from the Dickson-Vincent Duo’s original presentation of many families of parasites. I think of these shows as “TWiP – The Original Series”.

You two’s knowing banter riffing on the image of winding the worm coming out of the lesion on the patient’s foot onto a piece of wood, harkens back to the parasite covered on episode 37. I commend all fans to check that show out again.

The patient in TWiP 135’s case study is suffering from Dracunculiasis caused by  Dracunculus medinensis, aka the Guinea Worm.

Indicators were the man’s description of a painful, burning-feeling blister on the foot, the patient sticking his foot into a bath of cold water, the blister bursting open and the patient observing something moving around in the wound.

Daniel presented two additional questions to listeners to answer:


A1: Short answer: the man is from Ethiopia.

The ‘TL;DR’ (too long; don’t read) analysis follows.

The patient is reported as living in the U.S. for nine months, and previously living in a rural, resource poor region of his country before emigrating. Dracunculus is spread in dirty water where larvae and larvae-bearing copepods  accumulate from Dracunculiasis suffers comforting themselves by placing their feet/legs into cool water in streams or ponds.

The Carter Center has been instrumental in mounting an eradication campaign against Dracunculiasis. They publish regular status updates on their web site. In a January 2017 news release the Carter Center reports only three countries – Chad, Ethiopia, and South Sudan – reported, respectively 16, 3, and 6 new cases of Dracunculiasis. (

By some searching via Google I found U.S. immigration statistics from 2015. From these countries they are:

Country Cases

——- —–

Chad 75

Ethiopia             11,394

South Sudan      127


Based on the huge number of emigres from Ethiopia it is almost certain that Ethiopia is the patient’s country of origin. As a check, let’s do some basic statistics and explore the probability that an individual from any of these countries had the parasite.

Adding country population data, in Excel I construct the following table calculating the incident rate per person. Multiplying by the number of emigres yields the expected probability an emigre from that country was infected.

Country Cases Population Incidence # emigres Probability U.S.

(2016) (000,000’s) (/person) patient infected

Chad 16 14.04 1.14E-06 75 8.55E-05

Ethiopia 3 99.39 3.02E-08 11,394 3.44E-04

Sudan 6 12.34 4.86E-07 127 6.18E-05

The country whose émigré had the highest probability of infection is Ethiopia.

I am mixing data from different years to make these “back of the envelop calculations”, however perfect data for each year is not available to me. This adds additional uncertainty around the probability assessment. Would I be surprised if the patient were from a different country? No. Why? Events with small probabilities do occur, they are just less likely to do so.


The CDC’s web page “Parasites – Guinea Worm Management and Treatment” reports “There is no specific drug to treat or prevent GWD”. The illness requires daily management consisting of: gently pulling on the worm to remove it from the leg,  wrapping extracted length on a spindle of some sort to maintain tension, cleaning the sore to prevent infection, doing it again the next day all while be careful not to break and kill the worm to avoid other complications.”

In “Parasitic Diseases 6th ed” (p. 302) Despommier, write treatment may last 3-10 weeks. No wonder there was consternation over how long the man’s daily treatments would take.


If the Carter Center is successful with its efforts to eradicate this parasite then this show is a unique opportunity to vicariously engage with this soon to be extinct parasite. I’m attaching a screen grab image showing treatment which I took from the Carter Center’s website.

Happy Summer.


Theresa writes:

Hello TWiP team,

I am a recent TWiP convert and am thoroughly enjoying the episodes! I am PhD student in biological anthropology studying how lifestyle factors influence soil-transmitted helminth infection patterns among the indigenous Shuar of amazonian Ecuador. I travel to Ecuador each summer and collect fecal samples to diagnose STH infection and then help treat infected study participants. I am specifically interested in how lifestyle change in this population alters infection risk. Your podcast has helped reinforce the material I’ve learned in my parasitology courses and I’ve had a lot of fun trying to diagnose the case studies.

I would like to submit a guess for the most recent case study from episode 135. I believe the patient suffers from Dracunculiasis, or a guinea worm infection. He would have acquired this disease by drinking water contaminated with larva-infected copepods. Once consumed, the larva exsheath in the host duodenum, burrow through the mucosa, molt twice, then reside in the liver, subcutaneous tissues, or body cavity where they mature in 8-12 months (this is why it took so long for symptoms to become apparent after the patient moved to the U.S.). The mature males die and degenerate after fertilization, but the mature female is fertilized about three months post-infection and gravid females migrate to the subcutaneous tissue, causing the appearance of an open ulcer and a burning sensation. Infected individuals often seek out cool water to relieve the pain and contact with cold water stimulates the female to eject larva into the water (the female may then be visible as was observed he

re). Once in the water, the larva infect copepods and are subsequently transmitted to future human hosts.

Dracunculiasis treatment involves the slow and careful extraction of the female using a small stick. The female is wound around the stick (a few centimeters a day) until fully removed. This process is slow to ensure the worm does not break, which would allow the larva to escape into the subcutaneous tissue and cause further pain. In fact, some scholars contend the caduceus (the emblem of the medical profession depicting a pair of serpents wrapped around a staff) originates from this ancient treatment. The drug metronidazole can also be used.

This disease is extremely rare because it has been the target of intense efforts to eradicate infection through education and the implementation of water filtering techniques. The Carter Center in particular has focused on these efforts, and as a result Dracunculiasis is almost entirely eradicated. Based on the very limited cases diagnosed this year (according to the Carter Center), I would hazard a guess the patient is from Chad, which seems to contain the last pocket of this disease.

Thanks again for all you do, keep up the good work! I’ll definitely be downloading several of your old episodes to help keep me entertained during my travels and work in Ecuador this summer!

All the best,

Theresa (Eugene, Oregon)

Daniel writes:

Dear esteemed hosts

I confess! I have lapsed in my TWiP responses – I was going to reply to the “beaver fever” case, but time was short. However you have raised the stakes and I couldn’t miss a chance to get your textbook in hard copy.

This case sounds like a classic presentation of the guinea worm Dracunculus medinensis: a parasite on the verge of eradication.

Recent cases have only been reported in Chad, South Sudan and Ethiopia. Infection occurs when a person drinks water containing copepods that have ingested Dracunculus larvae. The symptoms are caused by the fertilised adult female migrating through subcutaneous tissue. New larvae are released when the painful ‘burning’ blister is placed in water and ruptures.

There is no available treatment other than to pull the worm out slowly by a few centimetres a day, to avoid leaving parts behind. I had been told that giving oral metronidazole might ease this process but would value your collective wisdom on this.

The extraction can take many weeks as the female adult worms may be 1 metre long.

Your book reminded me that this parasite is likely to be the origin of the rod of Aesclepius: an ancient symbol of medicine.

Keep up the good work!


Alexander writes:

Hi TWiP!

Your offer of free stuff has convinced this broke second year marine biology undergrad to have a go at one of your case studies. And although I’m probably the least qualified person to answer this I think I know the answer.

Before getting into my answer I’d like to say thanks for all the work you guys put into the TWiX podcasts. I find your podcasts help reinforce things I’ve learned in an enjoyable way along with new insights and literature recommendations.

My guess is Dracunculus medinensis or “Guinea worm” due to the distinctive symptoms described by Daniel  (painful blister on the foot and the pain relief and rupturing of the blister in water), and dixons comment about the disease being a lot less common than it used to be, down to only 126 recorded cases in 2014. The patient probably lived in Africa prior to moving to the USA. Guinea worm infections take about a year to develop after initial infection from drinking water containing copepods infected with larva. This fits with the 9 months the patient has been in the USA.

Daniel posed the question how long would it take to treat this patient. He mentions that the worm was wound around a stick, this is the standard treatment for a Guinea worm infection. The worm is wound out of the wound slowly over a prolonged period (a few days to weeks in some cases as adult female worms may be 100cm long) of time to avoid breaking it. If this treatment fails the only other option appears to be surgery.

Sources – CDC website, Parasitic Diseases 6th edition


Ps. In the unlikely event that I win and it isn’t inconvenient could I have the book signed? And thanks again for all the work you do!

David writes:

Dear Hosts,

I would like to toss my proverbial hat into the ring to win the wonderful prize of knowledge as a reward to correctly guessing the case study presented in TWiP 135.

I believe the man seen by Daniel’s colleague has come face to face with none other than the fiery serpent of the Israelites! These organisms are not burning snakes, however – they are a parasitic nematode known as Dracunculus medinensis – or the guinea worm.

The organism is contracted by the human host through consumption of water containing copepods hosting the L3 larvae of the nematode. The larvae are released following the copepod’s death, and penetrate the stomach and intestinal wall where they mature and reproduce. The male worms die, while the female worms migrate to the subcutaneous tissue and after a stunning one year post-infection, the female causes a painful blister on the host (typically on the leg or foot, but there have been instances of blisters forming on the hand or scrotum).The blister ruptures and the female worm emerges, causing severe pain and irritation, and in order to find relief from the pain, the host will submerge the afflicted extremity in water, where the gravid female expels her L1 young into the water. These are consumed by copepods, where they develop into the infective L3 stage and the life cycle begins anew.

Due to the long incubation period between infection and the development of the blister, the man infected most likely contracted the parasite a year before the blister emerged, which fits his timeline of having only been in the United States for 9 months. The telltale wrapping of the worm around a stick (which inspired the caduceus) also indicates the identity of the parasite quite nicely. As to this man’s origins, there are only a few countries with reported cases of guinea worm, as this parasite is coming nearer to extinction. The four endemic countries are: Ethiopia, Chad, Mali, and South Sudan, so it is hihly likely the man came from one of these countries.

As for the treatment of this disease, there is currently no medicine or vaccine available for dracunculiasis – carefully wrapping the adult female around a stick and slowly extracting the parasite works best for removal. Extraction time can vary between hours to weeks depending on the length of the worm and point-of-care decision making by the physician. However, secondary bacterial infections must be dealt with using antibiotics and the pain/swelling of the worm removal should be managed with ibuprofen or aspirin

A signed copy (from all three TWiP hosts, of course!) of either book prize would be a great addition to my collection: I own a copy of Parasite Rex signed by Carl Zimmer and quite a few records signed by their artists.

Thank you once again for the informative and entertaining podcasts.


David P.

Molecular Helminthology Lab, Cummings School of Veterinary Medicine

Kimberly writes:

Hello TWIPlettes!

Long time listener, first time emailer here. I am going to matriculate into the Texas A&M Medical School class of 2021 in just under a month and have been listening to your podcast for almost a year since taking my first Tropical Infectious Diseases class from Dr. Eric Brown while getting my MPH in Epidemiology at UT Houston and doing my practicum at Baylor, working with Chagas’ disease. I guess I will start with how I became interested in parasitology as it is quite an unique story.

I first became interested in infectious diseases after almost dying from a nasty case of Falciparum malaria when I was 18. I had taken a month long trip to Kenya to help build a medical clinic in a rural village on the shores of Lake Victoria. About a week after returning I started having terrible muscle aches, like I had run a marathon without training, followed by terrible shakes and fever. At the time I wrote it off because I would temporarily feel better and think that I had recovered. After a week of cyclic illness I went to an urgent care doctor who told me that it was probably just a “travelers illness” (whatever that is supposed to mean) and that I would get better on my own. He took some blood but insisted that the illness would resolve without intervention. Another week goes by and I am getting progressively worse, but luckily I have a standing appointment with my rheumatologist (I was diagnosed with Rheumatoid arthritis when I was 13) who requested the blood test results from the UC doc. I told my Rheumatologist that I had since noticed that my urine was turning the color of coke during my episodes. I’m not sure that this has been mentioned on the podcast previously but Falciparum malaria is sometimes referred to as “Black water fever” because of this unique symptom. My stomach was also killing me all of the time, so much so that between that and the muscle pain around my throat I could hardly eat anything. Over the course of my illness I lost about 15-20% of my body weight. He decided that we needed to repeat the blood tests because according to the UC report my white count was slightly elevated, but barely out of normal range. The next day I received a sort of panicked phone call from one of the office workers saying that I needed to come back immediately for a retest because there was an “issue” with the previous test. Apparently in the few days between my UC visit and my rheumatology appointment my Hematocrit levels had dropped from 42% (normal) to 25%. I was immediately referred to a hematologist/oncologist. Once I was finally able to get in to see him he initially told me that he believed that I had LEUKEMIA! At this point my hematocrit level had dropped to 13%. After insisting that he explain to me why leukemia would make my stomach hurt, he finally did an abdominal exam. It turns out that my severe stomach pain was caused by my enlarged spleen, which was about 3 times normal size at this point. It was so large in fact that when I laid down you could easily see it through my shirt. He was “intrigued” and so decided to do a blood smear “just in case”. After looking through many slides he finally found the culprit, a cell with the nasty little parasite nesting inside. He said that it was the only time that he had seen a case of malaria since being out of medical school. Luckily, this was during one of my “up” periods and I was able to walk myself across the street to the hospital and admit myself. The lady at the front desk had to call the doctor to confirm that they had indicated the correct diagnosis because here I was, a seemingly healthy young lady in San Antonio, TX, saying that I had malaria…In her defense, my parents didn’t believe it either. They came to see me in the hospital and thought for sure that they had misdiagnosed me because I looked fine. Within about 30 minutes of them arriving at the hospital I was trembling so bad that I couldn’t even hold a cup of water without spilling it. Soon my fever was spiking again and my hematocrit level was still dropping. Before it was all said and done I had had 3 blood transfusions, lost about 18 pounds and spent about 2 weeks in the hospital because of different complications. Oh and did I mention that there was a nation wide shortage of the standard treatment at the time? So I was substituted Malarone for the time being until I could get primaquine, which was months later.  It took a couple of months to fully recover and gain all of my weight back and stop losing my hair (I guess a reaction of my body under extreme stress). I often think back on your “One in 3 million” episode and what would have happened to me if my illness had gone any further.

I often tell people that it was the worst/best thing that ever happened to me. I don’t usually have to explain why it was the worst but I say it was one of the best things because that experience left me heavy heart and a new found passion for medical missions. That trip really sparked something in me that I just really can’t shake, a thirst for medical knowledge, interest in tropical infectious diseases and a desire to provide care for those that otherwise would not ever get it.

Now here I am, a couple degrees, many applications and 6 years later, a month from finally starting medical school. If it weren’t for these experiences or looking in those children’s eyes 6 years ago, knowing that some of them wouldn’t live to see their next birthday, that their mothers were willing to riot in the street to get mosquito nets to protect them, that I was a rare case of malaria here in the states, but 3 million people die from it every year, I don’t know that I would have persevered this far. It has been a long, sometimes very disappointing and emotional road but every step was worth it because I knew that eventually I could make a difference.

Sorry for the incredibly long email, but I thought I would share as that experience has given me a unique perspective into what some of my future patients have been through.

I will make the rest of my email short as this case was an easy one (at least I think… If I’m wrong y’all can just skip this part to save me my dignity).

Even with the very basic information provided, it is clear that the patient is suffering from Dracunculiasis, an extremely rare infection by the nematode Dracunculus medinensis. I knew this pretty much as soon as I heard “burning blister”. This disease is almost completely eradicated, largely due to the efforts of former president Jimmy Carter and the Carter Center. All current cases originate in Sudan, chad and Ethiopia. Chad was at one point free of guinea worm, but it is thought that the worm was reintroduced by undercooked fish.

Treatment would include supportive care once the worm emerges. The foot needs to be placed in a bucket of water, which can later be treated before being discarded. This signals the worm to emerge and release her larvae. A stick would then be wrapped around the end of the worm. The patient or a health worker would continue to wind the stick to slowly work the adult worm out of the opening. This may take up to a week to pull out the entire organism.

I would be very interested to know what country this man had come from as there are currently only a couple dozen cases a year.

Thanks for doing what you do and inspiring a future generation of parasitologists!

Jarrett writes:

Hello all,

The man living in Queens has come down with a case of Dracunculiasis, or Guinea Worm. He became infected in his previous country, likely Chad or South Sudan. Given the troubles in South Sudan, I would guess that this is where the patient is from. It is certainly in a resource limited region, and I imagine that contaminated water supplies abound, given the scarcity of practically all necessities. I’m happy he made it to Queens.

As to the question of care, apparently all one can do is wrap the worm around a toothpick or some such implement and, very carefully, wind the animal around it like some piece of diabolical spaghetti. As the text* states, wound care and pain management will be the components of his treatment going forward. How long will he require it? Hopefully no longer than a week. I see now the dilemma faced by the provider. Does this patient need a home healthcare worker to come to his residence to coax out the worm? Can the worm be extracted in this manner in one visit? Once free of the worm can the patient then travel to a wound care specialist for follow up care of the lesion, or will he require multiple home visits? I’m curious to hear what Dr. Griffin would recommend.

I have to say, if ever there was a classic presentation of Guinea Worm (albiet in Queens), this would appear to be it.

One last question: do we have any idea why these lesions tend to occur in the lower extremities? I know it is possible for them to occur elsewhere on the body, but the legs and feet seem to be where these things like to go to ruin someone’s day.

Much admiration to you all!

-Jarrett H.

Austin, Texas

*Parasitic Diseases, 6th ed. Would love a bound copy!

Tubby writes:

Greetings TWiPpers,

I am offering my identification of the new resident of Queens’ horrifying foot tenant.  It appears to be a Guinea Worm (Dracunculus medinensis).  Our patient might have moved to NYC from West Africa where this worm is still present.  The adult female worms form lesions on the lower extremities, which may open up when bathed in water, at which point she launches her eggs out into the world in search of new hosts.  After seeing the image in Parasitic Diseases 6th Edition I can understand why the patient would need someone to see him rather than visiting a hospital for aftercare.  

Depending on where the patient resides, trucking out to Queens might not be such a long journey.  It’s not so bad to drop by Astoria, but Jamaica is a different story.

Kind regards,


John writes:

Hi Doctors Twip,

I’d like to take a guess at the case study for Twip 135. As it happens, the differential for my first Twip guess to Twip 123 (which I think turned out to be cutaneous larval migrans) included some reading about the incredible eradication work by the Cater Foundation in relation to this scourge.

My guess is Dracunculiasis or Guinea worm disease. The disease is contracted by drinking water contaminated with water fleas which are infected with Guinea worm larvae (Dracunculus medinensis).

In the body, the larvae mature and mate. The  male dies and the female migrates to the limbs, usually to the feet. From ingestion, this process may take about a year. The patient in question has been in the US for about 9 months and so could have acquired the infection elsewhere.

The female moves to the surface of the skin and forms a particularly painful blister which feels like intense burning (hence the name Dracunculus or little dragons) which often causes the afflicted person (or animal) to immerse the afflicted limb in water for relief. Upon contact with water, the blister bursts, releasing hundreds of thousands of larvae, perpetuating the cycle.

Treatment involves bursting the blister in a controlled way (breaking the infectious cycle) and then extracting the worm by wrapping it around a stick or gauze. The process of extraction may take  from hours to a week or in extreme cases up to three months and is debilitatingly painful. During extraction, there is a risk of the worm breaking and the remaining section causing further complications. It’s not clear that a patient could extract the worm themselves.

In 2016 only 25 cases were reported, down from 3.5 million in 1986. Those cases were in Chad, Mali, South Sudan and Ethiopia. According to the Carter Foundation’s June 15th newsletter “The Guinea Worm Wrap-up” (ahem), the only human cases this year were in Chad, with some animal cases (in baboons and dogs) in the other countries.

Given the almost incredible decline in Guinea worm infections since 1986, the familiarity of the patient with the worm/infection is probably entirely dependent on their age.

Sorry for the novel but stuff like the Carter Foundation’s impending success, the victory over smallpox, the impending success over polio and all that stuff really give me a warm glow.

Thanks and regards,

John in Limerick

(where it was a hot 29°C this week).

Caroline writes:

Hello everyone.

I was excited to hear the case study this episode since I have been following the Carter Center’s campaign to eradicate Guinea Worm disease. According to the Carter Center, in 1986, 3.5 million people a year were afflicted with Guinea Worm Disease. In 2016, there were 25 reported cases. Definitely a public health success story.

Guinea Worm is transmitted when someone drinks water contaminated with Guinea Worm larvae. The female worm then grows to a meter long in about  year and emerges through the skin. This is a painful process and people often seek relief by submerging the painful lesion into water, stimulating the female worm to release larvae and continuing the infective cycle.

Guinea Worm Disease transmission is endemic in Chad, Ethiopia, South Sudan and Mali. However, in 2017, only Chad has had 5 reported cases so far. Guinea Worm eradication in Chad has been complicated by an increase in infections in dogs.

The WHO website states that 4 cases reported in 2017 were from four villages in Chari Baguirmi Region, Chad. So this is where I am going to guess our patient was infected with Guinea Worm.

Treatment consists of slow removal of the worm and prevention of secondary infection.

The life cycle of Guinea Worm is on the CDC website:

I love all the TWIX but TWIP is my favorite. I have worked in a medical laboratory for almost 20 years as a Medical Laboratory Scientist and the case studies are the most exciting to me. I can hardly wait for the new TWIP to be released!

I am currently in a graduate program at Johns Hopkins School of Public Health in Spatial Analysis for Public Health. I think spatial analysis of infectious disease will become increasingly important in the future.

Thank you all for fueling my passion!


Caleb writes:

Hello Philosophers of TWIP!

Upon hearing the details of the case study of episode 135, I immediately remembered  the first time I ever browsed through my downloaded version of Parasitic Diseases 6th Ed. (thank you!).  I had to do a double take at an unusually, even considering the subject matter, gross image of a large open wound on a human foot, with a worm inside it.  In my short career of trying to diagnose TWIP cases using this book, I’m learning that the pictures are often a great aid in coming up with a diagnosis.

Everything about the man in Queens with the foot blister that became an open lesion with something in it sounds characteristic of a diagnosis of Dracunculus medinensis.  According to the experts who wrote Parasitic Diseases, Dracunculus infects humans who drink water contaminated with copepods infected with L3 larvae.  The copepods release the larvae in the small intestine, who penetrate the wall of the small intestine, and migrate through the connective tissues of the host for up to a year, molting twice and maturing to adults.  The adult female worm finishes her migration in subcutaneous tissue, often on the lower extremities, such as in this case.  She uses her tail to anchor into the tissue, and secretes a toxin that induces local inflammation, causing a vesicle to form around her.  This was the blister that the patient in the case noticed.  This also causes an intense burning sensation, which is supposed to induce the host to dip the vesicle in water to find relief.  When that happens, the water causes the vesicle to burst and the uterus of the worm to prolapse, eventually releasing L1 larvae into the water.  Ah, the circle of life.  Definitive diagnosis is by locating the head of the adult worm in the skin lesion and/or identifying the larvae that are released into freshwater.  Treatment traditionally involves winding the worm gently around a thin stick to extricate it from the lesion.  Removing the worm seems to be the least of his worries, unfortunately, as the wounds appear to be nasty, and often result in 3-10 weeks of disability.  Wound care and pain management will form the bulk of his treatment.

It seems relatively likely that our patient has come from Sudan, or at least somewhere nearby.  This infection has nearly been eradicated in most regions, but still occurs in South Sudan.  This is also a region that has seen much recent immigration to the U.S.  The worm has a relatively long period that seems to be symptom free as it migrates to the subcutaneous tissue, so it is likely that he was infected in his home country before coming to Queens.  Until recently, it seems that it was a quite common infection, so I would guess that he probably had a decent idea of what it was, although I could be wrong.  

Thanks for the interesting cases, please keep them coming!  All the best,


Peter writes:

Hi TWiP Team.

This Case Study sounds like classic Guinea Worm disease or Dracunculiasis caused by the nematode Dracunculiasis medinensi.

A person is infected by drinking water with contaminated with tiny crustaceans or copepods, also called water fleas carrying  infective guinea-worm larvae.

The painful blister contained guinea-worm larvae that if released into a rural water hole could have been ingested by more copepods wherein they would mature to their infective stage and spread the disease to more people.

The adult female nematode may be 600 to 1000 mm long and will have to be carefully removed from the patients leg, traditionally this is done by winding the worm round a stick and slowly pulling it out a few centimetres at a time, taking care not to break the worm.

While alive this infection is largely symptomless, now that the nematode worm is dead it is no longer suppressing the immune system which responds to the body of the dead worm by causing painful inflammation.

According to the CDC:

“Sometimes the whole worm can be pulled out within a few days, but this process usually takes weeks. Medicine, such as aspirin or ibuprofen, can help reduce pain and swelling. Antibiotic ointment can help prevent secondary bacterial infections.”

As this patient is living in Queens and not in rural Africa, I wonder if surgical removal of the worm would be a viable option?



Toni writes:

Dear friends.

I am back. I am Toni from Spain.

Today in Zaragoza is partly cloudy and a maximum temperature of 28ºC.

Going straight to our interesting case study.

This case seems exceedingly easy for a microbiologist, describing a typical case of Dracunculiasis, caused by the nematode Dracunculus medinensis. This infection was much more widespread in the past, but nowadays only a few foci remain in a handful of countries, namely: Chad, South Sudan and Ethiopia. Being a francophone country, Chad would be the last on my guess-list. So, I guess our patient would have recently arrived from Ethiopia to the US. The disease is contracted by ingesting water contaminated with the water fleas (genus Cyclops).  The burning /itching sensation is an example of a host-manipulation-behavior from the parasite, because these symptoms force the patient to seek some relieve with the “refreshing” water contact. In that very moment the female just release a huge amount of larvae into the water. These larvae somehow seek and find the copepods (water fleas) and the cycle is completed.

What is curious in this case is not the clinical presentation, but to observe this disease in the middle of NY, thousands miles away from the countries where it is endemic. Dracunculiasis is an archetypal example of poor-people-disease and I wouldn´t expect this poor people coming into the US, just because this disease strikes the poorest people of the poorest countries.

From a Public Health point of view this is a very interesting disease. It probably will be the first parasitic disease to be eradicated ever. The Carter Foundation is probably the most important actor in the history of the control for this disease. Only political issues have been delaying the goal of global elimination. This of course will be possible only because D.medinensis has only a human reservoir, at least until now. And just, when we are in the brink of eradication, another reservoir has been discovered. And a very important one, our best friend: THE DOG. At this point I want to ask to our experts several questions that have come to my mind:

  1. How is possible that we, humans, in the whole history, have never be able to detect any canine case before?. I mean:
  2. Is it really a new reservoir or a NEWLY DISCOVERED reservoir?.
  3. And if it is really a new reservoir, could the pressure exerted over the shrinking-nematode-population have led to look for alternative hosts?.
  4. From an eradication point of view I think these are very bad news. How do you think this could change the global eradication goal?.
  5. From a zoonotic point of view, how could we control the disease in the most remote areas where the disease is endemic? Mass treatment for the dogs? Water-collection fencing to prevent the contact between dogs and water? As far as I know there are not effective drugs…

P.S. I think our audience are parasite lovers. I love to read everything about parasites, among many other topics. I really, really enjoyed reading People, Parasites and Plowshares and several of Robert Desowitz books. So, I think it could be a great idea to share with the audience different books about ecology, parasitology.

I am anxiously waiting for the next episode.

Thank you very much.

Helena writes:

Hi TWIP Team!

I am writing in from Davis, California where it is currently 89 degrees fahrenheit. A big improvement from the 105 degree days we experienced last week!

The case presented in episode 135 sounds like a classic case of Dracunculiasis caused by the guinea worm nematode, Dracunculus medinensis. It is a nematode that is transmitted to humans by consumption of water with infected copepods. After contaminated water consumption and the death of the copepods, the nematode larvae are released and penetrate the stomach and intestinal wall. They go on to mature in the muscles where females are fertilized and males die. The females then migrate to the extremities where they induce blisters and emerge! This whole process in itself takes a whole 9-12 months! (Lining up with our patient’s timeline) The burning pain from the emerging nematode causes the infected to seek water where the female nematode can release her youngins through ovovivipary! Once L1 larvae are released into the water they infect copepods, molt a couple times into an L3 larvae, and the whole cycle goes around again.

This infected man is most likely from Sudan, Chad, Mali, or Ethiopia where the remaining few cases are seen. Thanks to a large global eradication effort the number of cases has been reduced to 25 cases in 2016 from 3.5 million cases in 1986!! This simple control has been done primarily through the filtering of water through a nylon mesh and isolation from water of the infected.

The bad news for the infected man is that there is no effective drug treatment besides the use of an anti-inflammatory drug to ease the removal of the worm and some good pain killers! It could potentially be removed with surgery if worm is accessible but this risks an allergic reaction if not properly removed. The most common mode of removal is to very slowly wind the worm on a stick until removed. While painful and time consuming, the process of removing the worm is not difficult. If comfortable, the man can do this by himself everyday. In order to avoid secondary infection, however, the wound should be properly treated.

Interestingly, D. medinensis has been reported to infect canids, felids, horses, cattle, and non human primates possibly serving as reservoirs for the pathogen!

Thank you all for hosting this wonderful podcast! It is always a pleasure to listen in!

All the best,

Helena Vogel

UC Davis School of Veterinary Medicine

DVM Candidate | Class of 2021

PS I would love to add the hardcopy of Parasitic Diseases to my library!

BH writes:

Dear Doctors Twipping the Light Fantastic,

It took a few months, but I’ve finally listened to all the TWIP episodes in order. To celebrate I’d like to put my hat in the ring for an English version of the hard copy of Parasitic Diseases, 6th Ed.

Regarding the case study from TWIP #135:

The gentleman currently residing in Queens has a female Guinea worm (Dracunculus medinensis, Parasitic Diseases, 6th Ed, p299) in his leg.

This means that roughly a year before the blister appeared he ingested copepods infected with the worm’s L3 larvae. Since he’s from a rural, resource limited area, the infection source was likely contaminated water or undercooked fish / frogs.

My guess for the gentleman’s origin is Chad, somewhere along the Chari River. They’re dealing with canine outbreaks (carrying the apparently genetically identical human worm) in remote villages. Other possibilities are less likely (South Sudan, Ethiopia and Mali) as Chad’s the only country with reported cases in recent months. (I couldn’t find fine-grained demographics for Queens or travel rates from the top 4 suspects, so reported cases in the last year was the best I could do.)

Treatment is to keep the wound clean to prevent secondary infection, and to keep pulling that filarial nematode out a few centimeters per day, being very careful not to break it.

Since the adult females can range in size from 0.6 – 1.0 meters, and removal rate depends on what it’s wrapped around inside the leg, there is quite a bit of variability in how long we can expect the gentleman to have to do this.

The CDC’s website ( says that

Once part of the worm begins to come out of the wound, the rest of the worm can only be pulled out a

few centimeters each day by winding it around a piece of gauze or a small stick.

Sometimes the whole worm can be pulled out within a few days, but this process usually takes weeks.


I first heard about GWD in a youtube video about Neglected Tropical Diseases: “Kurzgesagt – In a nutshell”:

TWIP 37 was recorded earlier, but I’m late to the TWIP party so thought I’d share that tidbit.

Thank you very much for these excellent podcasts. Many future generations will be educated and entertained by your informative discussions and joyful enthusiasm for a long time to come.

Kind regards,


Vancouver Island,



A note about the writeup in Parasitic Diseases, 6th Ed: p302 under Treatment: There’s reference to figure 24.1, which is the wrong figure. It should probably be 25.1.


Ronald Jenkees is awesome! Thanks for introducing me to his music.

Brian writes:

Hello TWIPsters,

I could not resist the temptation of Parasitic Diseases and I am fairly confident with my guess. The gentleman has dracunculiasis caused by the guinea worm with his probable country of origin being South Sudan, Mali, Chad, or Ethiopia. These are the last remaining bastions of endemic guinea worm which with luck will be eradicated soon due to the efforts of the Carter Center’s eradication program.

The “worm around a toothpick” was a dead giveaway and immediately made me think of Dr. Despommier’s telling of the origin story for the “fiery snakes” on medicine’s caduceus from People, Parasites, and Plowshares.

Regards from Indianapolis,


PS I am a huge fan and have been listening to Vincent’s entire podcast empire for a few years.  A habit which helped me to decide to return to graduate school for epidemiology and now consider to further my education at either medical school or a PhD program.  Thank you for all that you do and I hope for many more years of listening to your stories and banter.

Ryan writes:

Hello esteemed doctors.

I am writing in for the case presented on episode 135. In fact, I’m currently attending the American Society of Parasitologists meeting in San Antonio, TX. Being a grad student, this is my first ASP meeting and I am thoroughly enjoying the company and the presentations. Finally, I have a room full of people as passionate about parasites as I am! Some day I will write in telling you about my thesis. But for today, let’s get to the case.

Listening to Dr. Griffin present the case, I started grinning from ear to ear (although not to be insensitive to the pain this man would be in) as the clues were very indicative of the parasite. My differential diagnosis would be that this man has had the misfortune to host a Guinea worm, Dracunculus medinensis. He would have picked this up from drinking water contaminated with copepods that were carrying infective larvae.

After doing some reading from the Parasitic Diseases 6th edition, I learned that it takes about 1 year from the ingestion of the larva for the female to migrate out of the intestines and travel down the leg where they create the blister. The burning blister is the worms way to ‘encourage’ its host to put its foot in water, so that the female can lay its eggs there and the life cycle can continue.

The Guinea worm infection is not fatal. However, attempts to remove the worm can result in an allergic reaction. Slowly pulling on the worm by wrapping it around the stick is a very old trick to remove the worm, but this is a slow, painful process. This could take up to 2 or 3 weeks of wrapping the parasite to get this long worm out of the leg. As Dr. Despommier has mentioned in the early episodes of TWiP, this wrapping of the worm is the inspiration for the medicine logo/crest found at many (or all) hospitals. Aside from this, there is nothing in the way of medication to remove the parasite. Some treatment to help with pain management and secondary infection risks. I hope the man had a quick recovery.

He most certainly would not have picked up this parasite living in Queens and would have brought it with him from his previous residing country. This man likely would have moved to the USA from northern Africa. The Carter Center website mentions 4 countries that the parasite has been observed in for the last few years and includes Chad, Ethiopia, Mali and South Sudan. The eradication program has been very successful to date and is closing in on no human cases. The fact that only 25 human cases were reported in 2016, it is very rare that one ended up in the USA!

Thank you for the time you put into making these wonderful and educational podcasts. Please keep the cases coming, and if possible I’d love to hear about more animal cases!

All the best,


Allan writes:

Dear Drs. TWIP,

To me it sounded immediately like the horrible symptoms of the “fiery serpent,” Dracunculiasis or Guinea Worm Disease.

When I started working in Primary Health Care in the early 1980s there were an estimated 3-4 million cases a year in some 20 nations.

Best guess is your patient is a relatively recent immigrant from one of the four remaining endemic nations of Mali, Chad, South Sudan or Ethiopia.

The Carter Center, Gates Foundation and many others have worked so long towards GWD irradiation and I understand its down to a tantalizing score of remaining cases each year.

It was still active in Benin and Côte d’Ivore when I worked there nearly 20 years ago.  I remember the hope that simple cheesecloth water filters (which can exclude the GWD infected copepods

from drinking water) would be the last nail in GWD’s coffin, but a bit like polio, we’ve realized it is more complicated. Now it appears humans and copepods aren’t the only species that can carry the “human” guinea worm, but also dogs and frogs, cats and catfish, as well as baboons.

This is an old and horrible disease, and the week or more that it will takes to slowly extract a guinea worm is agonizing.  And as with anything this painful and debilitating, it has been recognized and written about since Greek and even Biblical times. Dickson or Daniel could talk about the Rod of Asclepius better than me, as well as the downside of topical antibiotic or anti-helminths. But almost certainly your patient, at least growing up, would have seen others suffering from this infection and would suspect its what he has.

I know we all join former President Carter in hoping we live to see the day when this disease is gone.  

Mahalo for the best podcast out there

and keep up the fantastic work you’re doing!

Allan Robbins

Kona, Hawaii

Weather here is 30ºC or 86ºF, sunny in the mornings with showers most evenings this time of year.

Enjoying our kids home for the summer.


Why don’t you three come do a Rat Lung Worm workshop on the Big Island? We’ll host you, put you up for free, and you can do a live podcast from Kona?

Allan Robbins

University of the Nations

Global Health

Kailua-Kona, HI

Andrea writes:

Hello Twipitos!

I didn’t think I would ever be able to submit a guess to one of your cases unless the clue was something like “the answer rhymes with ‘grape perm’ and is sometimes found in undercooked pork and is rumored to be used as a diet aid”.

I think this poor man has a Guinea worm, the horror!

According to the CDC website the fact that the gentleman put his foot under water encouraged the worm to come out. I am guessing this is the reason why people that are infected with Guinea worms are not allowed to enter drinking water sources.

The treatment per the CDC:

The wound will need to be cleaned and then gentle traction applied to the worm to slowly pull it out until resistance is felt, being careful not to break the worm. Since these worms can be up to a meter in length I don’t think the toothpick is going to be enough.

The tension caused by the stick or toothpick is to encourage the worm the to come out.

Topical antibiotics should be used to prevent bacterial infections.

It is recommended to change the the bandage every day and aspirin or ibuprofen taken for the pain.

These steps are to be repeated until the whole worm is pulled out. Which can take several days to weeks.

This gentleman would have to have stronger intestinal fortitude than I would ever have in a billion lifetimes to do this on his own. I am not sure who would volunteer to go to Queens to help the patient but maybe he could be hospitalized. (I know, this would never be allowed)

The patient has been living in Queens for the last nine months and Dr. Griffin said that this was a recent case. I am going to guess that he did not pick up this worm in Queens because according to the The Carter Center’s website there haven’t been any cases of Guinea worm infections in the United States in 2016/2017 (until now?)

In 2016 only three countries reported human cases of Guinea worm: Chad, Ethiopia and South Sudan. This report is from January 2017, the totals may have changed. Perhaps this patient is from one of these countries.

I don’t know if I’m right or not but if I’m right does this mean that there has been a case of Guinea worm found in the US and The Carter Center will have to change its charts/totals?

In researching this case and I found that it is quite an incredible achievement of President Carter to have made the world wide eradication of Guinea worm a goal. It has almost been achieved. Quite amazing indeed!

There you have it, my first guess I may be wrong but I must say that now my skin is crawling! I really must want that book so I can have new and improved nightmares.

It is 65°F/18°C up here and partly cloudy Seattle. Where we are just north enough to miss the total eclipse!


p.s. again thank you for all you do. I really enjoy your podcast, maybe not finding out there is a such thing as a stool chart, and the others podcasts too!

p.s.s. sorry for the typos but as I said my skin is crawling and I need to finish this so I can go get something to drink to calm my skin and nerves down, it has taken me hours to write this little bit.

Ruben writes:

Dear Daniel,

 Some may say that you have gone too far in an attempt to attract more listener’s letters by dumbing down the difficulty of the diagnostic puzzle,  but I will not say that.

Instead I will submit my guess.

 Despite a worldwide effort to eradicate the dracunculiasis it is still a problem in Chad, Ethiopia, Mali, and South Sudan due to poverty, political instability and stray dogs. It is almost gone in Nigeria.  That is where the patient must have come from.

 The unfortunate Queens resident must have drunk water with larvae-carrying water-fleas, brought the Guinea worm in himself and watched the creature with amazement, trying to get out from his foot. The doc saw the head coming out first. Now the trick is to carefully take the worm out without breaking it into pieces. Do not use mebendazole! the worm is wanted alive. Only worry about extracting the worm completely and treating the wound, pain and potential allergies.

I have not idea how they do it in Queens.

Keep up your excellent work and be nice to Dixon.


Octavio writes:

Dear illustrious,

Today I’ll be brief, after my last time-monopolizing monologue, which I could not help think caused a bit of discomfort to the subject of my eulogy, and for that I apologize.

I believe the last case described a Dracunculiasis or Ginea Worm infestation.

“In 1986, there were 20 countries where Ginea Worm was reported. These amounted to about 3.5 million cases per year. 90% of the cases occurred in Africa. At that time an additional 120 million people of that Continent were at risk for GWD because of unsafe water supplies”, the World Health Organization reports.

Great progress has been made in the last thirty years. GWD is now poised to be the next disease after smallpox to be eradicated. As of January 2017, the International Commission for the Certification of Dracunculiasis Eradication (ICCDE) has certified 198 countries, territories, and areas, as being free from GWD transmission, with only 8 countries remaining to be certified: Kenya and Sudan are in precertification state; Angola and the Democratic Republic of the Congo are countries not known to have Dracunculiasis but yet to be certified, and four remain endemic countries: Chad, Ethiopia, Mali, and South Sudan.

Therefore, regarding the question “where did this patient came from”, it may depend on the year when this case was diagnosed by Professor Griffin’s colleague. Probably South Sudan or Ethiopia (I consulted the data at the Migration Policy Institute and the numbers seemed to point for a larger probability of these two origins).

Adult female worms come out of the skin to shed eggs in the water. It is then that the parasite may be pulled out (very gently) and fixed in place with a small stick, or with other object. As the female can be up to 170 centimeters long (no idea in furlongs, smoot, paces or the other exotic units the Axis of Medieval insist using), and usually one can only pull around 1 centimeter per day, the extraction can be prolonged to 170 days, that is to say it can be a process of more than 5 months.

The disease causes preventable suffering for infected people and is a financial and social burden for affected communities. The efforts of the CDC, WHO, UNICEF the Carter Center and Bill and Melinda Gates Foundation have been paramount in the eradication of this plague.

Meanwhile, genome sequencing has confirmed that dogs in Chad are infected by the same nematode worms (Dracunculus medinensis) that plague humans (M. L. Eberhard et al. Am. J. Trop. Med. Hyg. 90, 61–70; 2014).  This is very upsetting as it can mean that other potential hosts and reservoirs of the parasite may exist and continue to act as spread foci, delaying the total eradication of the disease. Nevertheless, it poses the opportunity to show how important it is to continue research on these diseases, that are known for so long, but at the same time keep having so much learn about.


Octavio Tick

Angel writes:

Hello TWiP hosts,

Writing from the island of Puerto Rico with clear skies and 83° F at 8:30 p.m. Recently I discovered your podcast and I must say it has been helpful for my commute to work which is around 1 hour away from my home. Since I have been hearing on average an episode a day I must say this week has been somewhat curious because the last 4 cases have ended one way or another in you guys discussing the patient’s stool. Nevertheless I enjoy the discussion and your dynamic, and hope to hear more interesting cases.

Now on to case study 135. The moment you started mentioning the painful blister with a burning sensation followed by it bursting when it was entered in water showing a parasite inside which the parasitologist  wrapped in a toothpick I remembered seeing this on TV. The parasite, which is Dracunculus medinensis also known as Guinea worm are found in feshwater and are ingested when drinking unfiltered water. The reason the blister is formed is because once the female has matured and reproduced it needs to return to the water to deposit their larvae (Hope Dickson explains the detailed cycle). The patient should have been from New Guinea since its the country from which he worm gets its name from. Treatment should take around a week. The reason for this is because the worm can only be removed using a matchstick little by little until it presents resistance and wait until the next day before resuming the removal. It must be prevented that the worm breaks because it could cause an allergic reaction and/or infection. The only prescription for the patient in this case should be a topical antibiotic to prevent infection in the wound since apart the matchstick method. Hope this helps in general.

Keep on the good work,


136lettersAnna writes:

Dear parasite pals,

Thanks to your podcast, I knew exactly what this was! (Attached photo.) So I thought of you and decided to write in.

The man in Queens has Guinea worm, which is nearly eradicated. There are still cases in Mali, South Susan, and possibly Chad where many dogs seem to be infected.

Finding a case imported into New York must have been a shock given how few cases are left in the world! I Googled “Guinea worm case New York” and didn’t see any press coverage about this case. Do you know if rare infectious diseases like this are routinely reported to CDC or elsewhere? I suppose it would be hard to keep the patient anonymous in this situation, being perhaps the only case for thousands of miles. But in general — How do we keep tabs on potential emerging epidemics here in the US when doctors see unusual things that they think are contagious?

Thanks for all that you do!


Gavin writes:

Dear TWiP Team,

Just a quick letter today to deposit my case guess for episode 135 involving the gentleman from Queens with a burning desire to soak his foot. This seems to be a clear-cut case of the ‘Guinea worm’ Dracunculus medinensis. In 2016, only 25 cases were reported out of Chad, Ethiopia, and South Sudan. Treatment involves slowly winding the worm “a few centimeters a day” on a stick and wound care to prevent secondary bacterial infections. Care must be taken not to break the worm. Female worms can be up to 100cm long, which mean this process could take weeks or even months depending on the length of the worm.

Thanks for the amazing podcast and the opportunity to win a copy of the Parasitic Diseases! I really loved the case from episode 130 (spider bite). I saw something very similar while shadowing an ID doc in rural Illinois.  


UCSF School of Medicine

Class of 2021

Maggie writes:

Dear Doctors,

I kept delaying my response, so I hope I’m making it in time for the recording of episode 136!

Case Guess

My guess for the case study is an infection with Guinea worm (Dracunculus medinensis). The female worm is emerging from the man’s foot, searching for a water body into which she will deposit her offspring, which will then be taken up by the copepod intermediate host. The man must have come to Queens from a subsaharan African country (maybe Sudan, Mali, or Chad?), where he would’ve contracted this infection by drinking up an infected copepod with his water (should’ve used Jimmy Carter’s straining straws!). This worm will be emerging from the man’s foot for several days, maybe even a couple of weeks, so daily care of driving to him to wrap the worm around a stick would be somewhat arduous for a full-time doc. It is possible that he could wrap the worm himself, but it seems risky to me since he will be in pain at the wound site and may risk ripping and killing the fragile worm if he gets impatient. If he does this, he then risks greater injury to himself from his own immune system’s reaction to the dead worm in his body, possibly including anaphylaxis and death.  

I am a student of parasitology, doing my Master’s thesis work on the systematics of an acanthocephalan (a.k.a. thorny-headed worms) genus that parasitizes fish and turtles. I still remember learning about Guinea worm in high school and it being my first inspiration for turning my general biology sights toward parasitology. What a crazy worm!

Quick Comment

I am a member of the American Society of Parasitologists and recently attended the annual meeting in San Antonio, TX (June 27-July 1), where there were lots of great talks by students and PI’s about an incredible range of parasitic infections and diseases. I would like to reiterate what all of you said on an episode back in 2015 in reply to someone casting about for graduate school options that conferences are a great way to meet potential advisors and to get inspired about understudied areas of any field. They are, and it was! If people are interested in getting involved with ASP, they will be updating the website over the next year or so, so it should hopefully be an easier interface for those looking to navigate the site and find out more. There are also several regional conferences associated with ASP scientists, if the national meeting is inconvenient.

Thank you all for doing what you do,


Writing from Washington, D.C., where it is a balmy 25 degrees Celsius with 74% humidity at 9:25am, set to get up to 32 degrees C.


Biology M.Sc. Student, SUNY Oneonta

Steven writes:

Good Day Twippers Vincent, Dickson, and Daniel!

The weather here in Mesa Arizona (a suburb of Phoenix) is ghastly; a horrid 42 C (108 F) with 30% humidity. In my opinion, the man from the case study on episode 135 has the text book diagnosis of Dracunculiasis, or more commonly known as Guinea Worm. Every symptom fits, from the delay of symptom onset, the blister, the relief upon submersion, the worm wrapped around the toothpick…  all of it. The treatment is nothing more than our average NSAID and removal of the worm which unfortunately can take weeks to complete. With the help of the Gates foundation, this parasitic infection has hit an all time low, but we (the world) still have cases reported every year. As of 2016 most (16) were reported in Chad Africa.

I thank you for your podcast and can’t get enough of the whole TWiX series of podcasts!

With the highest regards,

Steven a Medical Technologist in Scottsdale AZ

Wednesday, 21 June 2017 09:25

TWiP 135 Letters

Written by

Wink writes:

Vincent and Daniel,

I am willing to bet that you would not pass the Toxo/Sex/Internet study if it came through an oversight committee you were on. If so, why give it the TWIP bump?

Wink Weinberg (Atlanta)

Anthony writes:

The (lucky number 7) worms collected by Dickson Despommier (then in his technician phase (1962?)) from the woman in the hospital were tapeworms, not flatworms.


Noah writes:

Chinese text printed on the “sticker test” cellophane


dìyī rì

first day

Day one


náochóng jiǎnchá bōlizhǐ

pinworm check cellophane

Check cellophane for pinworms.

Sincerely, Noah

Case guesses:

David writes:

Dear Hosts,

Although the hiking woman from Colorado featured in the case of TWiP 134 uses iodine tablets while drinking water from streams, the symptoms she presents seem to point to a classic case of giardiasis (or beaver fever). She likely caught the parasite on one of her summer hiking expeditions after drinking stream water contaminated with the infective cyst stage of the Giardia parasite.

The Giardia trophozoites colonize the duodenum and jejunum in the small intestine and prevent host nutrient absorption, which causes gastrointestinal symptoms such as sticky, foul-smelling, fatty diarrhea (or steatorrhea), abdominal pain and nausea. Cysts are then passed into environment along with the feces, and the life cycle can continue.

Diagnosis for this parasite can be obtained through stool examination, ELISA testing, and an entero-test using a thread in a gelatin capsule that has one end taped to the inside of the patients mouth. The thread is later extracted and examined for the presence of trophozoites.

Treatment for the normally self-resolving giardiasis include a nitroimidazole medication (such as metronidazole, which is considered a first-line therapy by the CDC); however there has been recent evidence of drug resistance developing in Giardia.

Thank you once again for the informative and educational podcasts.


David P

Molecular Helminthology Lab at Tufts Cummings School of Veterinary Medicine

Octavio writes:

Dear Professors,

About a month ago, I came across the Podcast “This week in Parasitology”, and it has since become my loyal, entertaining, and extremely educational travel companion during my usual 3 hours-long driving around beautiful Portugal, the place where I send you my warmest regards from.

I am a Veterinarian, after a few other professional sidesteps, and I felt compelled to write you today, after hearing Professor DesPommier introduction in the first episode of TWiP, when he answered to Professor´s Racaniello question on why had he become a Parasitologist; His answer had to do with “doors opening”. A great story with somewhat of an emphasis on the importance of being in the right place at the right time, which in my opinion seemed to neglect all the work, dedication and talent the Professor has. A sentence ascribed to Thomas Jefferson goes like “I’m a great believer in luck, and I find the harder I work the more I have of it” and I believe this is also the case with Professor DesPommier as with illustrious Professor Racaniello and Professor Griffin.

As I said, I had a few other jobs before and in order to become a Veterinarian; I was a tomato paste factory worker, worked in restaurant kitchens, I was (and still am) a certified commercial diver, worked in private security, I held a couple of office clerk jobs, managed a bookstore, among other “survival experiences” that (in some cases thankfully) time ensured to blur out from my memory.

Nowadays and since 2013, I am working for a veterinary pharma company as a lecturer on their products, particularly in ectoparasiticides, the big fat teat on which  40% of all the vet pharmas gladly suck (smile).

As long as there are fleas and ticks in this world, there will be business –  and that’s not only because of the extraordinary biology, adaptation and resilience of these amazing and terrible creatures, but also because of the incredible misinformation, lack of information, or, as I find more frequent, utterly bewildering ignorance of the common citizen on the matters of parasites (parasites of their pets, internal or external, and parasites of their own).

I get a great pleasure and reward from what I do, because even within the constrains of a commercial activity, I feel that, every time I speak with someone (a pet owner, a Pharmacists, a Veterinary colleague, Technician or Nurse, an over the counter retailer, or whomever) I do my best to share with them my knowledge; It is a microscopic knowledge when I compare it with the likes of you three Gentlemen: I just hope it may be a microscopic embryonated egg of knowledge I can lay on my listener’s mind,and that it may hatch onto something useful and with relevance for the “one health”, just as you do with TWiP.

You do a truly great Service, and I learn every single time I listen to you. Please, keep on infecting us with your embryonated eggs of wisdom!

So that this already long message is just not a kilometer-long drooling-over-you exercise, I would like to add my hunch on what may be the cause for TWiP 134 case study – the fatty buoyant feces.

My guess goes to Giardia duodenalis, probably contracted due to consumption of water not completely treated with the iodine tablets this patient referred using, a situation described in the 1997 paper by Gerba, Johnson and Hasan “Efficacy of iodine water purification tablets against Cryptosporidium oocysts and Giardia cysts” (attached).

The epidemiological cycle is another case that reveals the intricate connections between human and wild fauna. In Urquhart’s Veterinary Parasitology it reads “There is evidence from the USA that Giardia from man which gain access to municipal water reservoirs may successfully infect wild animals, especially beavers. These then act as a source of contamination of domestic water supplies.”

Giardia trophozoites (Greek Throphós – the feeding state) should be the responsible for the duodenal, jejuneal (jejunii?) and ileal epithelial villi flattening with compromise of intercellular tight junctions, leading to malabsortion and steatorrhea.

Cryptosporidium would also be a suspect, but it is unusual that immunocompetent individuals should develop clinical disease.

The definitive diagnosis could be established by fresh stool smear examination, despite difficult, because the protozoans are very small (~15 micrometers), may not be passed in every sample, and this sample must be examined within 30 minutes after collection. Patience and systematic methodology are required. They are, nevertheless, very beautiful to watch.

In cats we have an ELISA fast test for Giardiasis, so I imagine quite more sophisticated kits exist for humans, including DNA amplification techniques.

If the diagnosis is confirmed, the anti-flagellated anti protozoan antibiotic metronidazole could be used to the treatment.

That is all for now.

I bid you farewell, and I am

Yours, “parasitophically”

Octávio Carraça Pereira

Post scriptum: “Pereira” is my surname and it means “Pear-tree” – almost a DePommier’s cousin My middle name, nevertheless, “Carraça” (it could be read karrassa) means “tick”.  Yes, I am a Veterinarian named Tick, who works with ectoparasiticides – I would not go so far as to say what Professor said about chance, fortune, fate or “Fado“, but it sure is quite a gag…

John writes:

Dear doctors Twip,

I think that the woman with the lighter-coloured, foul-smelling, sticky, floating stool from twip 134 has giardiasis.

The description of the stool seems to match steatorrhea (presence of excess fat in feces) which is characteristic of giardiasis. She had cramping and nausea which are also associated with the parasite.

She also consumed water from streams during camping trips (which may have been improperly treated)

Diagnosis can be made by direct microscopic observation of the trophozoites or cysts in a stool sample, by ELISA antibody test or by the delightful (though possibly obsolete?) string test.

The string test involves swallowing a gelatin capsule attached to a string. The string is taped to the subject’s cheek and the capsule is digested and travels down the gut. The string remains in place for several hours and is then withdrawn and the absorbent string is examined for trophozoites or cysts. Lovely.

According to Parasitic Diseases 6ed, treatments for giardiasis include metronidazole and  tinidazole, as well as paromomycin for pregnant women.


John in Limerick, Ireland where today the weather is 15° C with torrential rain after a week of clear skies and 23° C

P.S. I was listening to the team on TWiV discussing a paper a few episodes ago and  Vincent mentioned that two of the authors had ascaris. My first thought that flashed into my head was “that’s an odd thing to say but albendazole or ivermectin should clear it up”. Of course, what Vincent actually said was that the authors had asterisks. They were joint first authors. I’ve been infected by Twip.

Marcia writes:

Giardia lamblia

Johnye writes:

Good morning,

As always a pleasure to listen and learn.

As I listened to the Case Study for TWiP 134, it struck me that a more objective description of the patient’s stool might have been helpful. Dr. Griffin do you ever use the Bristol Stool Chart? I’ve found it very helpful in pediatric and adolescent medicine as a way of clarifying what a patient or parent is describing as abnormal. It is also something medical students and residents find interesting and, hopefully useful.

I’ve included 2 examples of the stool chart. There are many others that may be more or less appealing.

Now to think more about the clinical scenario and possibilities.

Best from Boston and Cambridge where it is currently mostly sunny and 18C.


(Your Cambridge Pediatrician)

JB writes:

Hey hey, Doctors!

I’d like to make a guess about the case study from episode number 134, the woman from Colorado experiencing weeks of foul-smelling loose stools.

The duration of her symptoms, as well as a few other facts in the case, has me leaning towards a specific diagnosis.

Floating, light-colored stools sounds like classic steatorrhea, and excess fat could also lead to an increase in “stickiness”. Many parasites can cause malabsorption in the intestines that could lead to steatorrhea, and some of them are water-born. What strikes me is that even though multiple people drank from the same water source, she became ill when her fellow hikers did not.

Had the entire party gotten sick, I would have suspected cryptosporidium. From what I’ve read, standard iodine disinfecting procedures aren’t very good at killing some crypto. If there were a lot of crypto cysts in the water, most everyone would likely have been infected.

The fact that only she got sick (and that only she drank out of her water bottle) leads me to believe that she did not practice sterilization as thoroughly as she may wish she had done.

So a freshwater-borne parasite that is easily killed by thorough iodine sterilization, and causes weeks of foul-smelling steatorrhea? I’m going with a diagnosis of beaver fever, aka giardiasis.

Thanks for all the great work, and here’s to many more wonderful episodes!

JB, Philadelphia

Iosif writes:

Dear Twip Team,

My guess for this week’s case is that our patient has a giardia infection. Cryptosporidium and giardia can both be obtained from dirty stream water and are more resistant to iodine treatment than most organisms. The giveaway is the fact that this diarrhea has been going on for a while and that the stool has turned fatty. The diagnosis can be made with a stool O&P or an ELISA. Treatment is with metronidazole.


Iosif Davidov

Hofstra SoM Class of 2018

P.S. I found this picture of giardia that I think would have been more appropriate a few months ago, but it was too good to pass up.


Mark writes:

Hello to This Week in Parasitology Hosts Vincent and Daniel,

Be nice to Dickson who is away traveling the world.

Below is my diagnosis for the case study presented by Dr. Griffin in episode 133. Late in the show, you, Vincent, requested listeners to send in an audio file with their diagnosis.

I am having fun by generating an audio file for this letter on my Mac using Siri’s voice. Let us see how Siri pronounces the names of worms that are suspected in this case. Those names are taneia solium, taneia saginata, or As-car-is lum-bri-coi-des.

Eggs of these parasites are spread through contaminated water, food, or soil. Daniel’s case notes indicated the young patient lived in a rural area, in a house with dirt floor, and drank untreated water from a stream. This establishes risk factors and possibility of infection.

Given that she is physically smaller than a younger sister indicates a nutrition problem. Her protuberant belly, hard to the touch, is consistent with a large mass of parasites in her intestines.

There are three candidate worms. We need to start to eliminate some. The girl’s diet is described as plantains, rice, beans. This eliminates taneia saginata which passes from cow to human during its life cycle. Taneia solium is eliminated as it passes from pig to human during its life cycle. This leaves ascaris lumbridoides

The final piece of evidence is that the girl’s mother observed a long, moving worm in the girl’s feces. To me, this piece of evidence validates the diagnosis above. As described in “Parasitic Diseases Sixth Edition” T. saginata is a segmented worm and its proglottid pieces may be observed in feces. T. solium is also a segmented worm and can be eliminated for the same reason. This leaves As-car-is lum-bri-coi-des as the parasite infecting the young girl.

The CDC’s website lists treatment with albendazole, mebendazole, or ivermectin as treatments while noting that the FDC has not approved Albendazole for treating ascaris.

In ancient history, when I started listening to TWiP, Dickson described Ascaris lumbricoides in episode 21. The episode’s image was a disgusting looking jar filled with dead worms. For those interested, I found the URL — it is:

Keep up the good work, and be nice to Dickson.


Anthony writes:

Here’s a Believe It or Not feature.  A freshwater mussel produces a fishing lure to attract fish to be infested with the mussel eggs:


Blackalls Park flying fox study to test for waterborne parasites

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

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