Effect Measure

The wild bird conundrum

What seemed pretty obvious at first, that wild birds could be and were long distance carriers of H5N1 is, like the birds themselves, still up in the air. The problem is that existing data on migrating wild birds has failed to show convincing evidence they are infected:

FAO officials last year voiced concerns that bird migration patterns might have spread disease Asia and Europe to Africa. But as elsewhere in the world, very few cases have been found among wild birds in Africa.

The Wildlife Conservation Society Field Veterinary Program Director William Karesh is among those attending the meeting in Bangkok.

“We tested thousands of birds in Africa, in Nigeria, in that area, and we cannot find a wild bird with the disease. [That] Does not mean it cannot occasionally get into them, but it is probably not going to go anywhere. It is a dead end,” he said. (Voice of America via HuliQ.com)

Maybe. Maybe not. The bird conservation community knows a lot about the subject but they aren’t exactly uninvolved observers.

Scott Newman, the FAO’s international wildlife coordinator, says the aim is to identify what countries need what kind of support and training to improve their surveillance of wild birds.

“We are hearing that wild birds have not been found to be positive if they are healthy, free-ranging birds. We are hearing, though, that dead wild birds are being found in various countries and they are confirmed positive for H5N1 avian influenza,” said Newman. “So, from a surveillance standpoint, some countries are doing healthy wild-bird surveillance. Others are just collecting dead birds and looking for disease. And so there is a range of surveillance activities and monitoring that are happening.”

There is no way to do this except to actually collect the data systematically. You can’t just figure it out. That means investing in an operating wildllife surveillance system. Until we have one, we are guessing.

Maybe we will guess right. But maybe not. And this is important information.

Comments

  1. #1 K
    September 5, 2007

    As you say, the conservationists are not an unbiased group of folks. I think Dr. Niman’s latest post is worth a look. http://www.recombinomics.com/News/09030701/H5N1_WB_Spread.html
    He is of course also not an unbiased commentator. Nonetheless he has been right an awful lot of the time.

  2. #2 Tom DVM
    September 5, 2007

    “We tested thousands of birds in Africa, in Nigeria, in that area, and we cannot find a wild bird with the disease.”

    The virus has either evaded the test/reagents etc. or there is a problem in processing samples.

    Either way, I don’t think we have seen a fraction of what is really going on with this virus.

    Time will tell.

  3. #3 birdFluNewsFlash
    September 5, 2007

    Why is it that when talking about the “wild” repository for the H5N1 virus, every one mentions only the wild birds?

    The H5N1 or the Bird-Flu virus has been found in a large number of mammals, ranging from domestic cats, dogs etc, to wild rodents, foxes and even Tigers!

    Surely small infected mammals of all kinds in the wild, are much more likely to NOT be found dead out in the open, as birds often are.

    These wild victims of the H5N1 virus and those animals who feed upon them, would not be easily noticed by us and therefore would be more suitable as “mutation chambers”.

    As we now know, the Bird-Flu virus has mutated already, it is now allowing limited human to human infection to take place.

    I believe that it may not be a bad idea, to in fact change the name of this virus at this time, from the Bird-Flu to some thing else.

    How about a poll on this blog, for the best new name for this virus?

  4. #4 revere
    September 5, 2007

    birdFluNewsFlash: Two reasons. The controversey concerns birds, and wild birds migrate long distances which small mammals don’t. The issue is how flu is spreading. We have frequently talked about the possibility of other reservoirs here, but in this context the issue is birds.

  5. #5 Tom DVM
    September 5, 2007

    Revere.

    Has H5N1 not followed exactly the migration routes from Q. Lake to migratory reserves in Egypt…and is now following established migratory routes from Africa and Egypt to Europe?

    How could they say that it is not a combination of trade in poultry and migratory birds?

    I don’t quite understand their issue.

  6. #6 Patch
    September 5, 2007

    Two years ago, folks all over the Net said H5N1 infections were imminent on North American soil. Experts too.

    It appears that the role of migratory birds in the transmission of H5N1 was overstated.

    K – I also think you overstate Niman’s accuracy.

  7. #7 M. Randolph Kruger
    September 6, 2007

    I think regardless guys of the modality of the bug and what the reservoirs are (might already be human). Its here, here to stay for a while and endemic in at least Vietnam, Thailand, China, and my particular favorite-Indonesia. It does matter how it gets here and there, but not really because we have already lost this particular battle. I just hope we dont lose the war.

    .

  8. #8 Attack Rate
    September 6, 2007

    Revere, I’m not sure if you saw the recent paper on immune suppression associated with migration and the effect of this on expression of avian influenza?

    If not I can send you the reference tomorrow from work. You might find it interesting reading.

  9. #9 Marissa
    September 6, 2007

    In Europe they have concluded that birds might be involved in relatively short-distance transmission but not long-distance transmission. Part of the argument runs that birds don’t have the energy to travel thousands of miles when they are sick (what about asymptomatic birds?) and part from genetic studies of clades.

  10. #10 Tom DVM
    September 6, 2007

    Marissa. Directly or indirectly, I have been involved in a lot of disease outbreaks-epidemics through the years.

    I have never seen anything like the response to H5N1.

    Maybe someone can explain rationally why there seems to be politics at every turn in this.

    H5N1 has clearly followed migratory routes in waterfowl that are asymptomatic (another first for H5N1) including marsh areas in Egypt and Nigeria…

    …I just don’t get their point…the connection to migratory birds is unmistakable.

  11. #11 anon
    September 6, 2007

    I never heard the theory that the H5N1 in Europe
    comes from Africa. Doesn’t make much sense.