The new bird flu: Is it serious?

There is a new outbreak of a bird flu in eastern China, referred to as H7N9. The first thing you need to know is that human populations have not been previously exposed (to any degree) to H7 or N9 type virus, so if this virus were to mutate in such as way as to spread human to human, the result could be very serious. Moreover, the “H” component of the virus is thought to have a genetic sequence that is known to readily mutate into form that would be target (bind to) human rather than bird cells.

The virus has been found in chickens, pigeons, and ducks in markets where live birds are sold. It is not known if there is a particular species harboring the virus, acting as a reservoir, but chances are there is one species of bird out there somewhere that has been passing the virus to other birds probably in the context of the live bird markets. It is possible that the reservoir is a domestic bird or a wild bird.

Health officials are concerned because the number of human cases seems to be rising dramatically. A few weeks ago a few people were infected and there had been a few deaths. The most recent information, probably a few days old, indicates that 24 humans have been infected of whom 8 have died, across 11 cities separated by hundreds of kilometers, but with most of the cases in a couple of locations including the vicinity of Shanghai.

Also, birds with the virus appear healthy. This is different than the more famous H5N1 bird flu, which made birds sick and thus made it possible to survey for areas where the virus was around.

The more pessimistic interpretation of all of this suggests that this is a “perfect storm” of factors to start a real pandemic. The virus is spread over a large area in heavily populated areas. The most direct ways of identifying potential reservoirs is unavailable. Humans are not predisposed with any sort of immunity to the virus. Genetically, the parts that would make it a human virus are primed to do so. The mortality rate is very high. And so on.

The more optimistic interpretation would note that a fast spreading disease like this is more likely to wipe itself out quickly. A high mortality rate is often seen in the early days of an emerging disease. People got sick and died because no one was expecting it, but with a better planned response moving forward, that rate should drop. We know a lot more about flu virus genetics and transmission than even just a few years go, so the science is a powerful tool. Most importantly, there is no human to human transmission of the virus at this time. Unless that happens, this is an important public health crisis and will have impacts on the economy linked to birds, but we are not all going to die. From this. And so on.

I’m not sure if this is behind a paywall, but most of the information here is from this piece in Nature. See also this from the CDC. CDC calls this an “evolving situation.” Haha.

____________
Photo Credit: IvanWalsh.com via Compfight cc

Comments

  1. #1 Kim Jong-Sung
    Pyongyang
    April 10, 2013

    If men = testosterone damaged women then why do women have penis envy ;)

  2. #2 Greg Laden
    April 10, 2013

    That was an absurd comment in an entirely inappropriate place. But, coming from an MRA gamer slymepitter I suppose we should not expect otherwise.

  3. #3 Richard
    San Diego
    April 10, 2013

    Check out the 2013 H7N9 Influenza A Outbreak link on the IRD home page to learn more about possible sequence determinants of human adaptation of this avian flu strain – http://www.fludb.org/brc/home.do?decorator=influenza .

  4. #4 Greg Laden
    April 10, 2013

    That site is surprisingly not very up to date.

  5. #5 Friday peak | Seeds Aside
    April 12, 2013

    [...] The new bird flu: Is it serious? [...]

  6. #6 Doug Alder
    April 14, 2013

    Greg – the most recent information is 60 infected 13 dead – a 21%mortality rate – see http://www.bbc.co.uk/news/world-asia-china-22141290

  7. #7 Greg Laden
    April 15, 2013

    Thanks. I’ve been watching closely, unsure as to when to update.

    The mortality rate is only of the reported infections, so given that extra sick people go to the hospital it is probably (we hope) a worst case scenario. So that’s good. A little.

  8. #8 Magpie
    April 17, 2013

    The Beijing boy who was asymptomatic is good news and bad news. The good is that the number of infected is likely to be much higher than reported, so the percentage-fatality rate is also likely to be a lot lower.

    The bad news is the same thing: the number of infected is likely to be much higher. That could mean the virus is getting WAY more opportunities to mutate to something better adapted to humans.

    It also means that it’s likely this flu will be like others: a complete bastard of a thing to halt if it gets going. SARS was comparatively easy by comparison: infected people almost universally had fevers, and only people with fevers were shedding much virus. That’s easy to track, even if you get a lot of false positives.

    If this, like other flus, has asymptomatic carriers, and / or people shedding some virus before they show symptoms, then the only regional-quarantine effort worth a damn will be a 100%, 6-day effort, which frankly no-one would have the political will to implement early enough (IMO).

    We’ll be down to social distancing, masks and hand-washing, antivirals and ECMO, and pneumovax and antibiotics – which are all good, they help, but we’re not likely to shut this down like we did SARS.

    Having said all of that, I’d happily put money on this NOT becoming a human pandemic. I reckon it’s more likely to settle down to something wussy, lurk around like H5N1 has, or vanish into the night altogether.

    Just, as I said on another blog, I wouldn’t put ALL my money on it.
    :)

  9. [...] The new bird flu: Is it serious? [Greg Laden's Blog] (scienceblogs.com) [...]

  10. [...] The new bird flu: Is it serious? [Greg Laden's Blog] [...]

  11. [...] The new bird flu: Is it serious? [Greg Laden's Blog] (scienceblogs.com) [...]