#17,773
Migratory birds for Europe, the Middle East, and Africa spend their summers in Siberia, Mongolia, or China, while here in North America more than 200 bird species spend their summers in the Alaskan Arctic Refuge and in Canada, which then migrate south via all four North American Flyways.While avian flu did not go away completely over the summer, outbreaks among poultry in the United States ceased for several months, and only resumed in early October (see chart below) coinciding with the fall southbound migration, resulting in the infection of 1.37 million birds .
In the first 3 weeks of November we've seen nearly triple that number (3.66 million), and there are additional outbreaks not yet included in this list (see Maryland Gov Statement & Wisconsin DATCP Statement).
The situation in Canada is equally bad, with their CFIA reporting 50 outbreaks in poultry during the first 21 days of November. Of those, 35 (70%) have occurred in British Columbia, mostly in the Fraser Valley region.
According to the Canadian Press, nearly 5 million birds have been lost over the past 30 days in British Colombia alone.
This winter will be the third consecutive bout of avian flu for North America, which arrived in Canada in December of 2021 (see Multiple Introductions of H5 HPAI Viruses into Canada Via both East Asia-Australasia/Pacific & Atlantic Flyways) before spreading widely, reaching South America a little over a year later.
Despite fully expecting its return, and having beefed up biosecurity measures (see USDA Defend the Flock Resource Center), poultry farmers are finding it difficult to keep the virus from infecting their flocks.
While it is possible that this year's bird flu virus has gained some transmissibility, the more likely explanation is that there is so much of the virus currently circulating among wild and migratory birds, that is has substantially increased the odds of breaching poultry farm biosecurity measures.
As a gastrointestinal infection in avian hosts, bird feces can be loaded with the virus, and can easily be contaminate farm feed or water supplies, or even be tracked in on worker's shoes, or vehicle tires.
For an indication of how prevalent the virus has become, we have the following announcement overnight from the City of Crestview, Florida - located in the western panhandle - which announces the closure of a local park for 60 days due to the detection of bird flu.
While the risks to humans from H5N1 remains quite low, and this action was taken out of `. . . an abundance of caution', it is a reminder that there is a lot of the virus in the environment right now - and that the risks are not zero.
That risk is undoubtedly higher for dogs and cats (see Netherlands: Utrecht University Study Of Stray & Domestic Cats For Evidence Of HPAI H5N1 Exposure) than for humans.
But people have contracted avian flu from pets (see J Infect Dis: Serological Evidence Of H7N2 Infection Among Animal Shelter Workers, NYC 2016). Which is why we've seen guidance from the CDC (see Bird Flu in Pets and Other Animals) and the UK's DEFRA on the importance of keeping pets safe from H5N1.
Since this is only November, and `avian flu season' can often last until late spring or early summer, it is too soon to say how much of an impact we'll see this winter. Hopefully poultry producers will get a better handle on biosecurity, and losses can be minimized.
But this is a reminder that we have entered yet another `new normal', and we'll have to find ways to adjust and adapt to this constantly evolving threat.
