What’s up with H7N9, the new avian influenza?

I have a new article up today at Slate, examining the emergent H7N9 avian influenzas, and a bit of a review of “bird flu” in general:

While we were carefully watching H5N1 in Asia and Europe, another influenza virus—2009 H1N1—appeared seemingly out of nowhere. Ultimately traced back to swine, this virus was easily spread between people, but unlike H5N1, it wasn’t any more deadly than our normal yearly influenza viruses (which, it should be noted, still kill on the order of 36,000 Americans each year). And now, while we’re still working on understanding how H5N1 and H1N1 have jumped between species, yet another influenza type has surfaced: H7N9.

5 Replies to “What’s up with H7N9, the new avian influenza?”

  1. Great article, Tara. It’s hard to imagine a better self-sustaining setup for breeding novel mutations of influenza than a society where you have lots of people, lots of poultry and lots of pigs all living cheek by jowl. Then use the excreta of all three to fertilise rice paddies and the germ factory will keep on being productive!

  2. was reading with interest until I got to the oft repeated lie – which I didn’t expect to see: “still kill on the order of 36,000 Americans each year”! you should know better…
    you’d have to go thru the CDC records for more than the last 20 years cumulatively, and you still wouldn’t approach a number like 36,000.
    just ask anyone / everyone you know if they’ve ever known anyone that died of the flu… if it was truly 36000/yr, you’d hear a lot of stories….

  3. Deaths from flu are tough to track, because often it’s the secondary complications of influenza infection–cardiovascular disease, bacterial pneumonia, etc.–that are the immediate cause of death. Indeed, the CDC has noted that flu deaths per year can vary widely, but 36,000 is in no way out of line. Some years can range up to almost 50,000 if it’s a very bad flu season; in a mild one, they can be as low as roughly 4,000. A 2005 paper put annual deaths from 1979-2001 at over 40,000 per year average: http://aje.oxfordjournals.org/content/163/2/181.full It just depends on the flu season, but in an 800-word article, that’s a lot more explaining than I was able to do, and the 36,000 is still a decent number.

  4. I’d be interested in some perspectives on the history of sanitation in China, from ancient times through today. The prevalence of pig/duck agriculture, the efficient but hazardous agricultural recycling loops of manures from various species, and so on, indicate a different paradigm at root, than what occurred in the development of Western societies. And, how does that paradigm mesh with both traditional Chinese medical theory, and current Western medical theory?

  5. Well, emerging zoonotic beasties are related to proximity between humans and animals, but it’s not necessarily a sanitation thing. For flu, birds have it in their faeces (it’s a gastro disease for them), but in those cases when we get it from pigs it’s just a matter of inhaling respiratory particles. That’s hard to prevent even in quite clean piggeries.

    Ultimately not a hygiene problem – it’s a problem of human activity encroaching on the territory of another species. Our domestic species interacting with the wild species, and humans (inevitably) interacting with those domestics.

    So this one doesn’t look like it’s coming from pigs at all – but wild birds carry it asymptomatically, and they give it to domestic birds asymptomatically. We’ve seen that some of the infected people seem to have gotten the virus from food preparation. Others have gotten it from simply buying a bird in a live poultry market. In other words, if (when?) this bird-related virus gets to western countries, there’s no reason to think we’ll be immune due to any sort of hygiene. We’ll probably do better because we have much less interaction with live birds, thanks to more widespread use of refrigeration, but it’s impossible to tell yet exactly how it’s being transmitted.

    And of course, if it adapts to humans it’s got a good chance it’ll be pretty damn bad. But there are probably a million pandemic potential candidates we have no idea about. Just because this one is more likely than some (it’s very recently gotten a fairly decent foothold in a new host with a lot of new infections, so if there are some selectable steps to make it better adapted it might get lucky quite quickly), that still doesn’t mean the next pandemic will BE this one. Probably won’t.

    But SOMETHING will. So hey, fund that public health, you people!

    (I’d put money on this *not* becoming a human pandemic any time soon, but I wouldn’t put *all* my money on it).

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