As the avian flu outbreak continues to evolve, it is critical for us to continue monitoring, testing and surveillance, especially as the current administration in the U.S. imposes massive cuts in funding and gags on research.
Timely and transparent communication to the public, even when information is not fully available or certain, is critical.
Though the avian flu is hardly new, there had been only one human infection since 2022. This has since increased to 69 confirmed cases in 11 states. A spillover effect has had dramatic effects on dairy cattle –what began in March 2024 with an infected dairy herd in one state has now spread to nearly 1,000 herds in 16 states.
Since this past January, a second spillover event has been identified. Initially, dairy herds were genomically sequenced to be infected from H5N1 virus, clade 2.3.4.4b, genotype B3.13. Genomic sequencing completed January 31 discovered several herds infected with H5N1 clade 2.3.4.4b, genotype D1.1. In addition, another change commonly associated with mammalian adaptation, PB2 D701N, was identified in these herds.
This second spillover means there is the possibility of additional spillover events, at a much faster pace. The D1.1 genotype is the same genotype found in the two most severe cases of human avian flu so far – one in the teen from Vancouver, B.C., and the other in an individual from Louisiana who died.
Repeated infections of herds already have occurred. Dairy herds in Idaho originally infected last spring were reinfected in the fall. While the United States Department of Agriculture (USDA) has said it does not see evidence of new infections or reinfections but instead a lack of clearance from the original illness, other experts have argued that these symptoms are more aligned with a second round of illness.
That immunity to avian influenza could be this short is concerning. It could mean avian influenza has the potential to circulate in dairy farms indefinitely and increases the likelihood of the virus evolving. Milder symptoms could also go un-detected, resulting in further spread and contamination of the milk supply.
And the list of domestic, wild and captive animals continues to grow. Avian flu has infected animals in zoos in New York City, Chicago, California and Arizona and include cheetah, mountain lion, white tiger, swamphen, kookaburra, ducks, seals, flamingoes and more. Most of the infected animals died. Reports of domestic cats dying due to ingesting raw milk and raw food contaminated with Avian influenza have occurred across the country. In addition, there has been a massive uptick in wild and migratory birds and wild animals infected and dying due in both the U.S. and Canada.
It is important to note that cats are highly susceptible to avian influenza viruses that primarily bind to specific cellular receptors called α-2,3 glycans; both cats and dogs have a higher concentration of these receptors in their respiratory tracts than humans. This makes it extremely important to keep domestic animals indoors and not feed them raw milk or raw food.
In two months, 41.4 million domesticated birds were culled in the U.S. alone because of H5N1
In just two months, December and January, 41.4 million domesticated birds were culled in the U.S. alone because of H5N1, causing the price of eggs to hit an all-time high. Similar culling of poultry has occurred over the past months in Canada. This is only going to get worse if the outbreaks continue, meaning similar rises in prices of chicken also are possible.
While the U.S. has announced that it will rebuild a stockpile of avian flu strain-matched vaccines for poultry, many poultry farmers have called for a vaccination campaign instead of repeat cullings. However, the decision to vaccinate poultry is complicated, with trade a major factor. The U.S. exports more than US $5 billion in poultry meat and products and many of the importing countries do not allow vaccinated poultry. This is because the vaccines do not prevent infections but only decrease disease severity, raising the risk of infecting poultry internationally. However, continued dialogue on this issue is critical given the potential impact on food security.
There is also a concern for reassortment which could occur when a person who is infected with both seasonal influenza and avian influenza, and those viruses exchange genetic material to make an evolved virus that’s more able to infect humans. This is particularly worrisome given the ongoing Influenza A outbreaks across North America. Though the overall risk of reassortment is low – for it to occur, both viruses need to infect the same cell; the new genetic make-up needs to be compatible and be able to reproduce and reinfect other cells – unmitigated avian influenza increases the risk of this materializing.
The good news is that there are several vaccine candidates for farm animals and humans, clinical trials are ongoing, and vaccine stockpiles are being updated. For now, the risk of human-to-human transmission continues to be low, though exposure to infected birds and animals increases the odds of infection. While this means there is no need for the public to panic, it does suggest that we should amplify our vigilance, especially in times when communication from U.S. health institutions may be lacking.
The key points to note are:
- Only drink pasteurized milk and thoroughly cook meat before consumption.
- Do not give your pets raw milk or raw food.
- Keep domestic animals, especially cats, indoors.
- If you come across any sick or dead wild birds, keep your distance. You can call your city’s wildlife phone line and report it.
- Make sure you keep your pets away from sick or dead wild birds as well.
- If you have a backyard farm, take all necessary protocols to keep your birds/chickens/cows away from wild birds. Use full and proper PPE if you think your bird, poultry or cow might be sick.
- If you are a poultry or dairy farm or animal husbandry worker, please refer to Centres for Disease Control’s guidance for enhanced protections.
