Regular readers know I occasionally get focused on natural history and life science issues, anything from post-viral syndromes to ‘2019-nCoV, the new coronavirus‘, screwfly to bonobos, and tiny cats to sex-chromosome syndromes. Last autumn and early this year, I wrote extensively about highly pathogenic avian influenza (HPAI), that is, bird flu, because I found it interesting. Like all flus, though, bird flu is seasonal. As the virus waned, so did news and therefore my interest. But, well, it’s baaaaaack….

Yes, as predicted, highly pathogenic avian influenza (HPAI) is on the upswing again in the US. (If you’d like to refresh yourself on all things bird flu, feel free to read my Avian Influenza Basics post.) Most of it, also as predicted, is our old friend H5N1, slightly different variants of which infect wild birds (mostly waterfowl), backyard flocks, commercial flocks, livestock herds, and wild mammals.

I won’t bother listing all the different increases in various flocks and herds here in the US since September. If you’re curious, you can follow the USDA’s reports. But I will mention one recent report on one particular mammal. Communications Biology documents the die-off of half the breeding population of a key population of elephant seals from H5N1. By ‘key’ this population represents more than half the total numbers of southern elephant seals: over 53,000 seals were wiped out. This will affect the numbers of elephant seals through the end of this century, a massive blow. I would not be the least bit surprised to find there’s a lot of this kind of thing happening off the radar—that this report represents the tip of the iceberg.

Here in the US, there have been scores of human cases of bird flu, mostly mild, with one fatality in Louisiana—though none since February. Until now. Right here in Western Washington, in Grays Harbor, an older person is hospitalised with the virus. This is not only the first human bird flu infection in the US since February but, notably, the first-ever known human case of a different HPAI: H5N5. The hospitalised and severely ill patient older and suffers several underlying conditions. Health officials who have modelled the behaviour of the two different HPAIs think H5N5 poses no more of a risk to people than H5N1. Which is great. As far as it goes. The problem with flu models is that because influenza viruses mutate so fast, with both HPAI and the more usual seasonal influenzas on the rise, the odds of a combination of both and/or a novel reassortant of either that behaves in dangerously unpredictable ways increases.

To be super clear: right now there’s zero grounds for anxiety. I’m merely pointing out that it’s probably time to start taking some simple, sensible precautions. And please do get vaccinated.