A Dog Flu Is Mutating Into a Virus That Can Infect Humans, Study Says
A Chinese study says that tracking the H3N2 canine influenza virus for 10 years has shown adaptions that allow the dog flu to recognize a human-like receptor.
The virus originally spawned from the bird flu and has stabilized within canines, although there’s still no jump to humans.
Continued adaptation in mammals could mean an eventual threat to humans.
The so-called dog flu may be moving ever closer to infecting humans, according to a new Chinese study.
The H3N2 avian influenza virus—highly contagious and lethal in the bird population—successfully jump to dogs around 2006. And it hasn’t gone away. Instead, according to a study published in eLife by scientists at the China Agricultural University, it is stabilizing and adapting to better recognize human-like receptors.
“Our results showed that canines may serve as intermediates for the adaption of avian influenza viruses to humans,” the study says. For a human population that “lacks immunity” to the canine version of the virus, that’s cause for concern, the study warns.
The bird flu spreads quickly in avian populations, but without the ability to effectively infect mammals, the concern over human-to-human transmission has as yet remained relatively low. While it is still a risk for humans that encounter the avian flu, the receptor molecule infected by the virus doesn’t pass the virus to other humans beyond the initial infection. That could all change with a successful adaption of the virus into a mammal, especially if that mammal is showing additional adaptation toward human transmission.
“The changes in the canine virus apparently are making it better adapted to transmit within mammals, as you might expect after such a long period in dogs,” James Wood, head of the department of veterinary medicine at the University of Cambridge, told The Telegraph. “The virus does not seem to pose particularly worrying health threats to dogs.” But Wood adds that, even though it may be good news that the virus has not yet hopped from dogs to other mammals, it might also mean that the virus just hasn’t hit on the right mutation yet. ”One might be more concerned about the longer-term pandemic potential in other species, such as humans.”
The study tested 4,000 sick dogs and found that one in 20 had the H3N2 virus, although it was a version of the virus that had mutated to better match the genome sequence of a human virus.
Ian Jones, University of Reading professor of virology, tells The Telegraph that the adaption into a more mammal-like virus is natural because of the time it has spent in the canine population. “At the moment,” he says, “I judge this data warrants attention but that the case for a threat is not clear.”
The study calls for continuous surveillance and risk assessments related to the canine flu, citing no pre-existing human immunity. Jones, though, says humans may offer up some defenses against the virus. And Wood notes that even as the dog flu numbers increase, albeit slowly, there’s no case of a human infected with the dog flu.
Just where the bird flu-turned-dog flu may go next isn’t a sure thing, but scientists will be watching.
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