#16,665
While it doesn't get as much media attention as our long-running COVID pandemic, the United States is in embroiled in our most serious avian epizootic since 2015 (see map below). Highly Pathogenic H5N1 arrived in Eastern Canada in December - likely carried from Europe by migratory birds - and has spread rapidly south and west since then.
This 2015 epizootic ran into June, and resulted in the loss of 50 million birds. But the virus quickly vanished - even in wild and migratory birds - over the summer, and did not return the following fall (see PNAS: The Enigma Of Disappearing HPAI H5 In North American Migratory Waterfowl).
Since then the HPAI H5 virus has undergone repeated reassortment events in Europe, and starting in 2016, has shown a greater propensity for extended carriage in some wild and migratory birds (see EID Journal: Multiple Reassorted Avian H5N8 Viruses In The Netherlands, 2016).
As a result, Europe has endured repeated - and very costly - avian flu outbreaks over the past 5 years.
Last year, after a handful of documented (but very mild) human infections - and increasing reports of mammalian infection in Europe (see here, here, and here) - HPAI EA H5Nx was elevated to having at least some zoonotic potential (see ECDC/EFSA Raise Zoonotic Risk Potential Of Avian H5Nx).
The risk to humans is admittedly low right now, but that could change over time.
For now, HPAI H5 is primarily a concern to poultry interests, and while this year's epizootic hasn't been as costly as the last one, the geographic range of this outbreak increases by the week. While the numbers are constantly changing, the USDA lists 95 outbreaks (excluding wild birds) over the past 8 weeks, resulting in the loss of over 12 million birds.
Five days ago, Minnesota - which was hard hit in 2015 - reported their first outbreaks of this epizootics (see USDA: Minnesota Reports HPAI H5 In Commercial and Backyard Flocks.
Yesterday the Minnesota Board of Animal Health issued the following statement, banning poultry sales and bird exhibitions, for the month of April.
News Release
For immediate release: March 31, 2022
Contact: Michael Crusan
Minnesota poultry sales and exhibitions temporarily banned for 31 days
Due to multiple detections of highly pathogenic avian influenza (HPAI) in Minnesota and surrounding states, the Minnesota Board of Animal Health is issuing a 31-day statewide ban on all poultry sales and exhibitions effective Friday, April 1 through Sunday, May 1. The ban includes all poultry community sales, swaps, fairs, exhibitions and other events where poultry and susceptible birds are brought together. The current H5N1 HPAI outbreak in Minnesota poses a high risk to poultry but low risk to the public and there is no food safety concern for consumers.
“Viruses like HPAI need hosts to continue to spread,” said State Veterinarian, Dr. Beth Thompson. “It’s our job to stop the spread of disease. Unfortunately, in this situation we feel one of the best things we can do for the health of all birds in Minnesota is to take a pause on poultry events through May 1.”
Direct sales of baby poultry either in stores or via mail by National Poultry Improvement Plan authorized sellers are still allowed.
Follow the latest information on HPAI and detections of HPAI in Minnesota, as well as resources for poultry owners on the Board’s website: www.mn.gov/bah/hpai. Additionally, the state activated a new HPAI hotline for anyone with poultry to ask questions or for anyone to report sick birds at 1-833-454-0156. Flock owners should be practicing strict biosecurity around their birds and reporting any suspicious illness to their veterinarian or the Board immediately.
The big unknown is whether HPAI H5 will become entrenched in North American wild and migratory birds - as it has the past few years in Europe - and become a perennial threat. Or will it disappear, as it it did in 2015, and await another introduction from across the sea.
While we await that answer, what this year already tells us is that the introduction of HPAI via migratory birds in 2015 was not a fluke, and since it has now happened twice in 7 years, we can expect it to happen again.
And with considerably more dangerous avian flu strains - like H5N6 - circulating in China, that should remind us that zoonotic threats anywhere can quickly become a zoonotic threat everywhere.
