Tuesday, December 22, 2009

US: Dog Tests Positive For H1N1



# 4181



In November, we began hearing reports of dogs in China that had tested positive for the novel H1N1 virus.  The first hint came from a CTV newscast (see China Worries Over Species Jumping H1N1) that I blogged about on November 11th.


On November 28th, we received more confirmation (see China Reports 2 Dogs With H1N1) with this news report from Xinhua News.


China urges intensified supervision on A/H1N1 flu in animals

www.chinaview.cn  2009-11-28 09:43:42

BEIJING, Nov. 28 (Xinhua) -- China's Ministry of Agriculture has called for intensified monitoring and investigation of A/H1N1 flu in animals after two samples from sick dogs were tested positive for the virus.


The veterinary clinic of College of Veterinary Medicine at the China Agricultural University reported Wednesday that two out of 52 samples from sick dogs were tested positive for A/H1N1 flu virus, the ministry said late Friday.


While conventional wisdom has been that dogs and cats are not normally susceptible to `human-adapted’ influenza, if you blog about influenza long enough – you stop being surprised when the `rules’ are bent.


Cats, after all, we were not thought likely to be susceptible to the novel H1N1 virus  either . . .  until, that is, reports of infected cats began to come in a little over two months ago.


Followers of the avian influenza story, of course, know that dogs and cats have both been infected by the H5N1 virus.


Dr. C.A. Nidom demonstrated in 2006 that of 500 cats he tested in and around Jakarta, 20% had antibodies for the bird flu virus.   For an overview of a number of other cases, see Apparently They Didn't Get The Memo.


We’ve not heard of dogs being infected by the H1N1 virus before, although there have been reports of dogs being infected by the H5N1 avian flu.   See also Study: Dogs Can Shed H5N1 Virus.


Of course, H5N1 is avian flu, with different receptor binding domains than human flu.   


While it probably happens more often than we know, yesterday the first confirmation of canine infection with the novel H1N1 here in the United States was released by Idexx labs.


Here are excerpts from the IDEXX Labs press release


INDUSTRY ALERT from IDEXX Reference Laboratories:H1N1 influenza virus infection confirmed in household pets

A dog from the Katonah Bedford Veterinary Center in Bedford Hills, New York, has tested positive for the H1N1 virus on the IDEXX H1N1 Influenza Virus RealPCR™ Test.


A 13-year-old dog had a several-day history of not feeling or eating well, a dry cough and a fever on presentation to its veterinarian. The dog was treated for pneumonia and improved with hospitalization and supportive care. The dog tested positive on the IDEXX H1N1 Influenza Virus RealPCR Test. A more detailed case description is available.


In the United States, the H1N1 influenza virus has been confirmed recently as the cause of respiratory disease in several ferrets and cats resulting in more than one death in each of these species. These infections were believed to have been contracted from infected owners. There was an unconfirmed report of dogs infected in China in late November. The case described here is what is believed to be the first reported case of a dog infected with the H1N1 influenza virus in the United States. The dog’s owner had also recently tested positive for H1N1 influenza virus. The Iowa State University Veterinary Diagnostic Laboratory has confirmed independently that the influenza strain is the new pandemic strain circulating in the human population and not a swine-specific H1N1 strain.

(Continue . . . )



The concern here isn’t so much that dogs or cats will give the virus to humans.  Transmission from pet to owner has not yet been established (although it is certainly possible).  


Right now, there are plenty of opportunities to contract the illness from humans, without worrying about getting it from a pet.


It is far more likely that a pet will catch this virus from their owner, than the other way around.


Apart from the scientific curiosity as to why novel H1N1 should have a wider host range (swine, turkeys, felines, canines, ferrets, etc.) than most influenza viruses, the real concern is over the possibility that H1N1’s promiscuous behavior could lead to the creation of mutated or reassorted strains of the virus.


reassortment in a host


Of course, this same mutation could occur in swine, birds, humans, or practically any other host the virus can infect.  


So we shouldn’t stigmatize our pets as potential incubators of a mutated virus.  It could just as easily happen in a turkey, a pig, or even your next door neighbor.


There is also a theory that states that the more susceptible hosts a virus can find, the less evolutionary pressure it will have to mutate.  


If true, the ability of this virus to infect more hosts could be seen as good news.  Of course, it’s just a theory . . .   


All of which means we have a lot more to learn about this virus in particularly, and influenza viruses in general, before we can begin to predict how all of this turns out.


Stay Tuned.

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