"Beware of Dog" gains new meaning
Scott McPherson
in Politics and government, influenza and infectious diseases
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The astonishing, but not surprising report from Wageningen University and Research Center, The Netherlands -- published in the August CDC journal Emerging Infectious Diseases -- is a gripping read.
Influenza researchers have suspected for some time that common domesticated animals such as dogs and housecats might be vectors of influenza.
So, too, does the government of South Korea -- and exercised that belief in horrifying fashion eight months ago, well before scientific research confirmed their actions. At left is an article from MSNBC, dated Nov. 27 of last year. The South Korean government made the strategic decision to euthanize every non-human creature within 3 kilometers of any bird cull from confirmed high-path H5N1.
Note that AP story's statement from "animal health experts" that there was "no scientific evidence" that dogs and cats could pass the virus to humans.
Based on the published study, they might want to rethink that statement. The Dutch researchers concluded that dogs are able to catch H5N1, remain asymptomatic, and shed virus from their nasal passages. Some dogs did not show antibodies to H5N1 until 14 days into their infection. More importantly, the dogs did not die. At least, not in the experiment. The research paper references the common belief held among flu researchers that Thai dogs were/are carriers of H5N1, and references an article confirming Thai dog H5N1 infection in the December, 2006 issue of EID.
The paper also references a particularly stressful experience in Florida over the past several years; namely, the outbreak of H3N8 canine influenza in 2004. Originally confined to racing greyhounds, the disease spread through veterinary offices and animal hospitals, and led to the temporary closure of dog parks and dog shows across Florida. Many dogs died. Here in this study, the story is magnified that the virus was an equine influenza that jumped to dogs.
I quote directly from the study:
Conclusions
Our results demonstrate that dogs are susceptible to infection with avian influenza (H5N1) virus and can shed virus from the nose without showing apparent signs of disease.
Moreover, receptors for avian (H5N1) virus are present not only in the lower part of the respiratory tract of dogs but also in their trachea and nose, which are potential portals of entry for the virus. Influenza virus infection of dogs was first reported in 2004 (6). Influenza (H3N8) of equine origin caused outbreaks in greyhounds in Florida and has since been found in dogs in >20 US states (7). The course of experimental infection of SPF dogs with subtype H5N1 resembles that of the experimental infection of dogs with the subtype H3N8 (6): all dogs seroconverted, and some excreted virus without obvious disease. In contrast to the experimental outcomes, natural infections with influenza (H3N8) resulted in serious illness, death, and widespread infection for dogs. This finding warrants special attention to the potential course of avian influenza (H5N1) infection in dogs. Therefore, dogs’ contact with birds and poultry should be avoided in areas with influenza (H5N1) outbreaks to prevent possible spread of virus and human exposure to influenza (H5N1) virus that might have been adapted to mammals. http://www.cdc.gov/eid/content/13/8/pdfs/07-0393.pdf
As you have just read, lab experiments and the natural course of influenza infection are frequently at odds. The H3N8 fed to dogs in the lab did not kill them. In contrast, naturally-acquired H3N8 kills dogs. That is a mortar round lobbed at those who used an article from last year to say that H5N1 would "never go pandemic." Their ammunition was that since CDC researchers could not make a "human" pandemic H5N1 virus in the lab after a few tries at reassortment, it meant it could not likely be done in the wild. Poppycock.
As we also know, dogs are not the only domestic pets singled out for consideration as H5N1 vectors. The Indonesian government has a systematic plan in place to swab housecat mouths and noses at the first sign of an H5N1 case in humans or poultry. The photo at left is of an Indonesian government official checking common housecats for H5N1 at a checkpoint in Jakarta.
The idea that our own pets might unwittingly turn against us is unthinkable. Can you imagine the social implications if American decision-makers in government were to adopt the same policies as their South Korean counterparts? In light of this study, can this thought be very far from the consciousness of every person studying this disease?
Perhaps if we told this story to the American people -- that their pets would potentially be taken from them and euthanized during an outbreak of a pandemic strain of influenza -- that the public would then pay better attention and demand more research toward averting same. Maybe that would rip their minds from whatever it is that they are thinking about these days.
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