I'm Getting Worried About Bird Flu

I'm getting worried about bird flu (aka H5N1 avian influenza). Calling it bird flu is a bit of a misnomer now, as recent news makes it clear that it is spreading widely in mammals, now including cows. This has been happening for a while now, but it's getting widespread enough that the mainstream media is picking up on it.

The New York Times looks at recent large outbreaks (gift link), especially among sea lions, that have devastated colonies along the coast of North and South America. 

What they found was staggering: The virus had killed an estimated 17,400 seal pups, more than 95 percent of the colony’s young animals. 

 The catastrophe was the latest in a bird flu epidemic that has whipped around the world since 2020, prompting authorities on multiple continents to kill poultry and other birds by the millions. In the United States alone, more than 90 million birds have been culled in a futile attempt to deter the virus.

There has been no stopping H5N1. Avian flu viruses tend to be picky about their hosts, typically sticking to one kind of wild bird. But this one has rapidly infiltrated an astonishingly wide array of birds and animals, from squirrels and skunks to bottlenose dolphins, polar bears and, most recently, dairy cows.

The worry here, of course, is that the virus may mutate in a way that makes it easily transmissible among humans, where it has a mortality rate of at least 33 percent. 

In his Ground Truths blog, Eric Topol provides a more detailed summary of what we know about how H5N1 is spreading, starting with this.

Confirmation of H5N1 infected dairy cattle herds in 8 states. But the FDA report yesterday of commerical milk PCR positivity strongly supports that the cattle spread is far wider than these 8 states. Important to emphasize that (PCR) is testing for remnants of virus, not live virus, which would be unlikely with pasteurization. Other tests, assessing potential evidence for any live virus (egg viability and culture), are to be reported by the FDA going forward. Limited culture tests are all negative to date for any live virus in milk.

 Gizomdo has more details on the spread to cows and the response by the FDA.

Genetic evidence released to the outside science community on Sunday suggests that the initial spillover event from birds to cows may have occurred as early as December 2023, months before the first known cases were reported by local officials. And, coupled with the discovery of H5N1 in store-bought milk, it’s now looking likely that outbreaks are much more widespread than currently tallied.

“The dissemination to cows is far greater than we have been led to believe,” Eric Topol, founder of the Scripps Research Translational Institute, told CNN on Tuesday.

The major worry with avian influenza strains such as H5N1 is that they could someday develop the right assortment of mutations that would allow the virus to spread easily between humans while also causing severe illness in many. So, the longer it’s able to remain in cows, the greater the likelihood that some strains will adapt and become better at transmitting between mammals, humans included.

I'm not worried about finding genetic material from the virus in milk (pasteurization will kill any live virus), but I wouldn't drink unpasteurized milk (never a good idea even without the threat of H5N1). And keep a good stock of N95 masks around, even if you aren't using them now.