Can Humans Get Norovirus From Their Dogs?

800px-Golden Retriever Hund Dog
Washington, D.C. - April 10, 2015 - Human norovirus may infect our canine companions, according to research published online April 1 in the Journal of Clinical Microbiology, a publication of the American Society for Microbiology. That raises the possibility of dog-to-human transmission, said first author Sarah Caddy, VetMB, PhD, MRCVS, a veterinarian and PhD student at the University of Cambridge, and Imperial College, London, UK. Norovirus is the leading cause of food-borne illness in the United States, according to the Centers for Disease Control and Prevention (CDC). 
 
The research showed that some dogs can mount an immune response to human norovirus, said Caddy, who will be a junior research fellow at the University of Cambridge, beginning in August. “This strongly suggests that these dogs have been infected with the virus. We also confirmed that that human norovirus can bind to the cells of the canine gut, which is the first step required for infection of cells.”
 
Caddy and collaborators performed the latter research using non-infectious human norovirus particles, which consist solely of the virus’ outer protein, called the capsid. The capsid is the part of the virus that binds to host cells. By itself, it is non-infectious because it lacks genetic material. (The non-infectious capsid is the basis for a new norovirus vaccine which is being tested in clinical trials, said Caddy).
 
Nonetheless, it is not clear just how much of a problem canine infection and transmission may represent for humans, said Caddy. Despite dogs’ apparent susceptibility, the investigators failed to find norovirus in canine stool samples, including those from dogs with diarrhea. They found it in serum samples of only about one seventh of 325 dogs tested.
 
Additionally, it is not yet known whether human norovirus can cause clinical disease in dogs Assuming that dogs become infected with human norovirus as per this study, it also remains unknown whether they could shed the virus in quantities sufficient to infect humans—although clinical investigators have estimated that as few as 18 virus particles can cause human infection.
 
Moreover, it is yet to be determined whether dogs play a role in the epidemiology of some outbreaks of human norovirus. Some of the biggest outbreaks occur in places from which dogs are absent, such as on cruise ships and in hospitals.
 
Norovirus, which causes vomiting and diarrhea, is extremely contagious among humans. It infects 19-21 million Americans annually--more than six percent of the US population--according to the CDC. Those infections may result in as many as 71,000 hospitalizations, and 800 deaths.
 
The impetus for the study came from her veterinary practice, and her status as a dog owner, said Caddy. “As a small animal veterinarian, I am often asked by dog owners if they might be able to pass infections onto their dogs, or if their dogs are contagious to them,” said Caddy. “There are plenty of anecdotal cases of dogs and humans in the same household, having simultaneous gastroenteritis, but very little rigorous scientific research is conducted in this area.”
 
“Until more definitive data is available, sensible hygiene precautions should be taken around pets, especially when gastroenteritis in either humans or dogs is present in a household,” said Caddy.
 
 
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The American Society for Microbiology is the largest single life science society, composed of over 39,000 scientists and health professionals. ASM's mission is to advance the microbiological sciences as a vehicle for understanding life processes and to apply and communicate this knowledge for the improvement of health and environmental and economic well-being worldwide.

MRSA Can Linger in Homes, Spreading Among its Inhabitants

mrsa

 

WASHINGTON, DC – March 10, 2015 – Households can serve as a reservoir for transmitting methicillin-resistant Staphylococcus aureus (MRSA), according to a study published this week in mBio®, the online open-access journal of the American Society for Microbiology. Once the bacteria enters a home, it can linger for years, spreading from person to person and evolving genetically to become unique to that household.

 

MRSA are strains of the bacterium Staphylococcus aureus that are resistant to almost all antibiotics related to penicillin, known as the beta-lactams. Since the 1990s, community-associated MRSA infections, mostly skin infections, have been seen in healthy people. The predominant community-associated strain of MRSA, called USA300, is virulent and easily transmissible.

 

For the study, researchers used a laboratory technique called whole genome sequencing on 146 USA300 MRSA samples. These samples were collected during a previous study from 21 households in Chicago and Los Angeles where a family member had presented to the emergency room with a skin infection found to be caused by USA300 MRSA. During that study, published in 2012 in the journal Clinical Infectious Diseases, investigators visited the homes of 350 skin infection patients, culturing their and their family members’ noses, throats and groins for bacterial colonization. Among 1,162 people studied (350 skin infection patients and 812 household members), S. aureus colonized at one or more body sites of 40 percent (137 of 350) of patients with skin infections and 50 percent (405 of 812) of their household contacts.

 

For the current study, investigators evaluated the samples to understand transmission dynamics, genetic relatedness, and microevolution of USA300 MRSA within households. They also compared genetic information from these MRSA samples with previously published genome sequences of 35 USA300 MRSA isolates from San Diego and 277 USA300 MRSA isolates from New York City, as well as with the completed genomes of the bacteria USA300 TCH1516 and FPR3757. They created an evolutionary tree to show the relationships among the bacterial strains.

 

The researchers found that isolates within households clustered into closely related groups, suggesting a single common USA300 ancestral strain was introduced to and transmitted within each household. Researchers also determined from a technique called Bayesian evolutionary reconstruction that USA300 MRSA persisted within households from 2.3 to 8.3 years before their samples were collected, and that in the course of a year, USA300 strains had a 1 in a million chance of having a random genetic change, estimating the speed of evolution in these strains. Researchers also found evidence that USA300 clones, when persisting in households, continued to acquire extraneous DNA.

 

“We found that USA300 MRSA strains within households were more similar to each other than those from different households,” said senior study author Michael Z. David, MD, PhD, an assistant professor of medicine at the University of Chicago. Although MRSA is introduced into households rarely, he said, once it gets in, “it can hang out there for years, ping-ponging around from person to person. Our findings strongly suggest that unique USA300 MRSA isolates are transmitted within households that contain an individual with a skin infection.”

 

USA300 broke down into two big groups or clades, with the vast majority of isolates from Los Angeles genetically different from those in Chicago. Fluoroquinolone-resistant USA300 clones emerged around 1995 and were more widespread in Los Angeles, San Diego and New York City than in Chicago.

 

 “The study adds to the knowledge base of how USA300 MRSA has spread throughout the country,” said study coauthor Timothy D. Read, PhD, an associate professor of infectious diseases at the Emory University School of Medicine in Atlanta. “We’re also getting hints at how it evolves inside households. Decolonization of household members may be a critical component of prevention programs to control USA300 MRSA spread in the United States.”

 

The study was supported by the National Institutes of Health.

 

The article is available online at http://mbio.asm.org/content/6/2/e00054-15.

 

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mBio® is an open access online journal published by the American Society for Microbiology to make microbiology research broadly accessible. The focus of the journal is on rapid publication of cutting-edge research spanning the entire spectrum of microbiology and related fields. It can be found online at http://mbio.asm.org.

 

The American Society for Microbiology is the largest single life science society, composed of over 39,000 scientists and health professionals. ASM's mission is to advance the microbiological sciences as a vehicle for understanding life processes and to apply and communicate this knowledge for the improvement of health and environmental and economic well-being worldwide.

 

New Compound Protects 100 Percent of Ferrets, Mice, from H5N1

 


(colorized transmission electron micrograph of Avian influenza A H5N1 viruses)

Washington, DC - March 4, 2015 - Since 2003, the H5N1 influenza virus, more commonly known as the bird flu, has been responsible for the deaths of millions of chickens and ducks and has infected more than 650 people, leading to a 60 percent mortality rate for the latter. Luckily, this virus has yet to achieve human-to-human transmission, but a small number of mutations could change that, resulting in a pandemic. Now a team of investigators from St. Jude Children’s Research Hospital, Stanford University Medical Center, and MacroGenics have developed an antibody which has proven 100 percent protective against the virus in two species of animal models. The research is published ahead of print February 11, in the Journal of Virology, a publication of the American Society for Microbiology.

Antivirals have been potential sources of protection, but they are hampered by the propensity of viruses to rapidly mutate, which often results in resistance. “We have seen this in H5N1 viruses,” said corresponding author Richard Webby, PhD, a Member in the Infectious Diseases Department at St. Jude Children’s Research Hospital, Memphis, TN, and Director of the World Health Organization (WHO) Collaborating Center for Studies on the Ecology of Influenza Viruses in Lower Animals and Birds.

Vaccines, Webby said, must be developed to match each flu virus, something which would likely take at least six months following the emergence of a pandemic. Additionally, vaccines are somewhat ineffective in the elderly and immunocompromised individuals.

The investigators turned to antibodies, which target antigens on viruses as specifically as keys to locks, thus disabling them. Regardless, mutations can render antibodies ineffective. “Our solution was to make a ‘dual-specific’ antibody by combining two different antibodies that attach strongly to H5N1 viruses into a single antibody-like molecule,” said Webby. That, he said, should make it much harder for resistance to emerge. The new compound is called FcDART, for Fc (the type of fusion protein) Dual-Affinity ReTargeting molecule.

A single, low dose of the FcDART provided complete protection against lethal H5N1 viruses in laboratory models of influenza. “This dose could be given one day before infection—for example, to protect healthcare providers—or up to three days after,” said Webby.

“Laboratory models are rough approximations of what might happen in humans,” said first author Mark Zanin, a post-doctoral fellow in Webby’s lab at St. Jude. “We did see complete protection against H5N1 in ferrets, which have long been used as a model for human flu, so we are confident in our results.”

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The American Society for Microbiology is the largest single life science society, composed of over 39,000 scientists and health professionals. ASM's mission is to advance the microbiological sciences as a vehicle for understanding life processes and to apply and communicate this knowledge for the improvement of health and environmental and economic well-being worldwide.

Novel Fungus Accumulates Critical Element for Green Energy from Mine Drainage, Industrial Waste

WASHINGTON, DC - February 20, 2015 - Japanese investigators have demonstrated that a novel fungus can bioaccumulate the industrially important “rare earth” element, dysprosium, used in the magnets of generators and motors, as well as in smart phones and other electronics, and high technology, generally from mine drainage and industrial liquid waste. This discovery could lead to recycling dysprosium from these wastes, said first author, Takumi Horiike, researcher in the Rare Metal Bioresearch Center at Shibaura Institute of Technology, Saitama, Japan. The research was published ahead of print on February 20 in Applied and Environmental Microbiology, a journal of the American Society for Microbiology.

The characteristics that make dysprosium valuable in large generators, such as those in direct current wind turbines, and in electric motors—as in hybrid and battery-driven automobiles—are its powerful magnetism, and it’s resistance to being demagnetized by external magnetic forces and high temperatures.

Until recently, dysprosium was mined almost exclusively in China. In 2010, China slashed exports of rare earth elements by 40 percent, sending prices skyrocketing. That inspired efforts to seek new supplies of rare earths, including new mines and this effort to develop microbial recycling.

The first step in the latter effort was to find a microbe that would assimilate dysprosium. Horiike, and corresponding author Mitsuo Yamashita, PhD, Professor in the Department of Applied Chemistry at Shibaura Institute of Technology, took sediment and liquid samples from 72 stations, including abandoned mines, industrial waste sites, and waste disposal plants in Japan, and analyzed these in search of microorganisms ingesting dysprosium.

They discovered that the novel strain of fungus, Penidiella sp. T9, was assimilating dysprosium, and at very high efficiency. It can ingest nearly its own dry weight of this rare earth element. It accomplishes this by mineralizing dissolved dysprosium at the high acidity of pH 2.5, on par with the acidity of mining and industrial waste in which it was found. The investigators also discovered that Penidiella sp. T9 can assimilate other rare earth elements, which are similarly important for green energy and other high tech.

Penidiella sp. T9 is the first eukaryotic (multicellular) microbe that is able to bioaccumulate dysprosium during growth, but several bacterial species have been reported to do so, although not at highly acidic pHs.

Yamashita says that it is not known what advantage, if any, the ability to bioaccumulate dysprosium confers upon the fungus. “The T9 strain grows without dysprosium, so we know that dysprosium is not necessary for growth,” he said.

Whether microbial recycling of dysprosium will ultimately prove inexpensive enough to contribute to supplies of dysprosium is uncertain, in no small part because the current research is still at a very early stage. But it also depends on changes in world markets for dysprosium. Mining outside of China following the throttling of exports reduced that country’s share of rare earth elements from 93 to 86 percent, and greatly lowered prices, which now stand around $500/kg. And in 2013, the World Trade Organization ruled that China was violating WTO rules with its price-hiking quotas, which led to that country dropping its quotas early this year. Even if recycling dysprosium never becomes cost-effective, it will be necessary to remediate the mines, as dysprosium is somewhat toxic. “Our goal is both to purify the contaminated water, and to recover the rare metal,” said Yamashita. One way or another, Penidiella sp. T9 may well prove to be green.

The article is available at http://aem.asm.org/cgi/reprint/AEM.00300-15v1?ijkey=G8NB3CCE5CDBc&keytype=ref&siteid=asmjournals.

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The American Society for Microbiology is the largest single life science society, composed of over 39,000 scientists and health professionals. ASM's mission is to advance the microbiological sciences as a vehicle for understanding life processes and to apply and communicate this knowledge for the improvement of health and environmental and economic well-being worldwide.

What We Know and Don’t Know About Ebola Virus Transmission in Humans

MINNEAPOLIS/ST. PAUL - February 19, 2015 – A new comprehensive analysis from the Center for Infectious Disease Research and Policy (CIDRAP) at the University of Minnesota, involving leading International Ebola researchers, examines what is known about transmission of the Ebola virus and cautions that the public health community should not rule out the possibility of respiratory transmission. Prior to the current Ebola epidemic in West Africa there have been only 24 reported Ebola outbreaks with approximately 2,400 cases reported over the previous 39 years. Evidence suggests that direct patient contact and contact with infectious body fluids are the primary modes for Ebola virus transmission, however, this evidence is based on a limited number of studies.

The analysis was published today in mBio®, the online open-access journal of the American Society for Microbiology.

The analysis further examines what we already know about the transmission of the Ebola virus and what we need to learn about its transmission. Due to the limitations of current data on Ebola virus cases, the role of aerosol transmission remains unclear. Transmission potentially occurs via virus-laden aerosols generated through the emission of body fluids during vomiting, diarrhea or coughing. It is advised that more studies are needed to better understand aerosol transmission in spreading the disease.

“Available evidence demonstrates that direct patient contact and contact with infectious body fluids are the primary modes for Ebola virus transmission, but this is based on a limited number of studies,” said Michael Osterholm, Ph.D., MPH, McKnight Presidential Endowed Chair in Public Health and director of CIDRAP and lead author of the analysis. “In our comprehensive review, we address what we know and what we don’t know about Ebola virus transmission. We also hypothesize that based on the best scientific evidence, Ebola viruses have the potential to be respiratory pathogens with primary respiratory spread.”

The Center for Infectious Disease Research and Policy (CIDRAP), founded in 2001, is a global leader in addressing public health preparedness and emerging infectious disease response. Part of the Academic Health Center at the University of Minnesota, CIDRAP works to prevent illness and death from targeted infectious disease threats through research and the translation of scientific information into real-world, practical applications, policies, and solutions. For more information, visit www.cidrap.umn.edu.

Media Contact:
Aleea Khan (akhan@asmusa.org)

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