#18,356
While undoubtedly underreported, the toll that H5N1 is taking on domestic cats - which the USDA only began tracking 9 months ago - continues to rise. Last week, 10 cats were added, and today 7 more are added to the list (106 out of 521 reports).
Among them is a single cat from New Jersey, even though last week's report from the NJ DOH indicated at least two cats had tested positive, and others on the property were ill. This week four states reported cases in domestic cats (Washington, New Jersey, Oregon & Colorado)
At the same time, we are seeing very few other animals reported (by the states), even though there appears to be a lot of virus in the environment. Many states have yet to report any wildlife infections (see map above), while many others have only reported 1 or 2.
Admittedly, many infected animals either recover - or die unnoticed in the wild - particularly in less accessible areas like the Everglades of Florida, the bayous of Louisiana, or desert and mountainous regions out west.
But it does seem as if some states are far more diligent in seeking out, testing, and reporting cases than others. Since the evolution of H5N1 can occur in many different hosts, our `don't test, don't tell' attitude - which also extends to livestock - leaves us wide open to nasty surprises.
Since the emergence of a new, more mammalian-adapted H5N1 virus in 2021, we've seen a number of outbreaks in cats around the world (see reports from Poland & South Korea). In those outbreaks, as well as several recent cases in California and Oregon, the consumption of raw meat and/or milk was the likely exposure.
In other cases cat have been believed infected through predation of wild birds or rodents, or via exposure to contaminated areas outside of the home (see California: San Mateo County Warns Residents After Stray Cat Found With H5N1).
While the USDA lists 106 domestic cats infected with H5N1 (and > 5 dozen wild or captive large cats), no one knows the real number. Feral cats are unlikely to be tested for the virus, and we've seen reports of household pets that died, but were never tested.
Although we haven't seen it happen with HPAI H5, cats have been shown capable of transmitting avian flu (H7N2) to humans (see J Infect Dis: Serological Evidence Of H7N2 Infection Among Animal Shelter Workers, NYC 2016), raising concerns over their potential role in spreading the H5 virus, or affecting its evolution.
