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  • Ecologic Immunology of Avian Influenza (H5N1) in Migratory Birds

    EID Journal Home > Volume 13, Number 8?August 2007


    http://www.cdc.gov/eid/content/13/8/1139.htm<!-- InstanceEndEditable --><!-- content_starts_here //--> <!-- InstanceBeginEditable name="Article Content" --> Volume 13, Number 8?August 2007

    Perspective

    Ecologic Immunology of Avian Influenza (H5N1) in Migratory Birds

    Thomas P. Weber* and Nikolaos I. Stilianakis*?
    *Joint Research Centre, Ispra, Italy; and ?University of Erlangen-N?rnberg, Erlangen, Germany


    Abstract
    The claim that migratory birds are responsible for the long-distance spread of highly pathogenic avian influenza viruses of subtype H5N1 rests on the assumption that infected wild birds can remain asymptomatic and migrate long distances unhampered. We critically assess this claim from the perspective of ecologic immunology, a research field that analyzes immune function in an ecologic, physiologic, and evolutionary context. Long-distance migration is one of the most demanding activities in the animal world. We show that several studies demonstrate that such prolonged, intense exercise leads to immunosuppression and that migratory performance is negatively affected by infections. These findings make it unlikely that wild birds can spread the virus along established long-distance migration pathways. However, infected, symptomatic wild birds may act as vectors over shorter distances, as appears to have occurred in Europe in early 2006.

  • #2
    Re: Ecologic Immunology of Avian Influenza (H5N1) in Migratory Birds

    Originally posted by Anne View Post
    EID Journal Home > Volume 13, Number 8?August 2007


    http://www.cdc.gov/eid/content/13/8/1139.htm<!-- InstanceEndEditable --><!-- content_starts_here //--> <!-- InstanceBeginEditable name="Article Content" --> Volume 13, Number 8?August 2007

    Perspective

    Ecologic Immunology of Avian Influenza (H5N1) in Migratory Birds

    Thomas P. Weber* and Nikolaos I. Stilianakis*?
    *Joint Research Centre, Ispra, Italy; and ?University of Erlangen-N?rnberg, Erlangen, Germany


    Abstract
    The claim that migratory birds are responsible for the long-distance spread of highly pathogenic avian influenza viruses of subtype H5N1 rests on the assumption that infected wild birds can remain asymptomatic and migrate long distances unhampered.
    Nonsense.

    Comment


    • #3
      Re: Ecologic Immunology of Avian Influenza (H5N1) in Migratory Birds

      for example :
      We agree with Yasu? et al. (5), who considered data on which migratory birds are considered responsible for long-distance spread of HPAI (H5N1) to be incomplete, inadequate, and often incorrect. For example, in a large number of cases involving wild birds in 2005 and early 2006, the Organisation Mondiale de la Sant? Animale (Paris, France) did not report the species concerned. Lack of knowledge of the species involved in outbreaks among wild birds is just the tip of the iceberg. Even if species, age, and sex of affected birds were recorded correctly, many other interpretative issues often emerge.

      that s the non sens

      Comment


      • #4
        Re: Ecologic Immunology of Avian Influenza (H5N1) in Migratory Birds

        Originally posted by Anne View Post
        for example :
        We agree with Yasu? et al. (5), who considered data on which migratory birds are considered responsible for long-distance spread of HPAI (H5N1) to be incomplete, inadequate, and often incorrect. For example, in a large number of cases involving wild birds in 2005 and early 2006, the Organisation Mondiale de la Sant? Animale (Paris, France) did not report the species concerned. Lack of knowledge of the species involved in outbreaks among wild birds is just the tip of the iceberg. Even if species, age, and sex of affected birds were recorded correctly, many other interpretative issues often emerge.

        that s the non sens
        No, the nonsense is the assumption that H5N1 is dependent on a single bird and that initial infection is linked to symptoms. The first line in the abstract makes the paper a non-starter.

        Another reason is the fact that long range migratory birds like bar-headed geese can fly 1000 miles in 24 h,

        Comment


        • #5
          Re: Ecologic Immunology of Avian Influenza (H5N1) in Migratory Birds

          Many reports do in fact not identify in sufficient detail the species of wild birds concerned. If you browse through the OIE reports there are numerous references to ?wild ducks? etc. This certainly lacks specificity. The species was reported only in 15% of the 167 wild bird cases on the German national reference laboratory?s list of confirmed outbreaks in February and March 2006. There?s the additional problem that sampled populations can be composed of migratory and non-migratory individuals. There?s huge variation in migratory behavior between sexes and age classes of the same species.

          Where does the abstract claim that H5N1 is dependent on a single bird and that initial infection is linked to symptoms? Why is the latter absurd? Where is the evidence for infected, asymptomatic wild birds? And why does it matter that bar-headed geese can fly 1000 miles in 24h?

          The case of the bar-headed geese illustrates quite well the fundamental lack of knowledge of avian migration in the communities of researchers dealing with avian flu. The incident at Lake Qinghai occurred in May-June 2005. Bar headed geese leave India in February and arrive on the breeding areas in March or early April (no cases were reported in India or anywhere along the migration route). The geese must thus have been in the Qinghai area for several weeks before the outbreak started on 4 May. Did H5N1 remain miraculously latent for several months in the geese and then decided to turn pathogenic for no good reason?

          Comment


          • #6
            Re: Ecologic Immunology of Avian Influenza (H5N1) in Migratory Birds

            Welcome Tompe.

            Comment


            • #7
              Re: Ecologic Immunology of Avian Influenza (H5N1) in Migratory Birds

              Originally posted by tompe View Post
              Many reports do in fact not identify in sufficient detail the species of wild birds concerned. If you browse through the OIE reports there are numerous references to “wild ducks” etc. This certainly lacks specificity. The species was reported only in 15&#37; of the 167 wild bird cases on the German national reference laboratory’s list of confirmed outbreaks in February and March 2006. There’s the additional problem that sampled populations can be composed of migratory and non-migratory individuals. There’s huge variation in migratory behavior between sexes and age classes of the same species.

              Where does the abstract claim that H5N1 is dependent on a single bird and that initial infection is linked to symptoms? Why is the latter absurd? Where is the evidence for infected, asymptomatic wild birds? And why does it matter that bar-headed geese can fly 1000 miles in 24h?

              The case of the bar-headed geese illustrates quite well the fundamental lack of knowledge of avian migration in the communities of researchers dealing with avian flu. The incident at Lake Qinghai occurred in May-June 2005. Bar headed geese leave India in February and arrive on the breeding areas in March or early April (no cases were reported in India or anywhere along the migration route). The geese must thus have been in the Qinghai area for several weeks before the outbreak started on 4 May. Did H5N1 remain miraculously latent for several months in the geese and then decided to turn pathogenic for no good reason?
              The "dead bird don't fly" argument was DOA. It never made any sense. In many instances, infected birds don't shed virus for several days. Initially they are healthy. Thus, one bird like a bar headed goose could fly 1000 miles before showing any symptoms. The bird could then die, but the H5N1 would already be at the new location, infecting more birds. It is like a relay race, The key is the location of the baton, not the condition of the runner after the baton has been passed.

              However, the above is really not relevant at this time (other than to show how silly the premise is).

              Qinghai H5N1 has already gone from nature reserve to nature reserve (Qinghai to Erhel and Chany Lakes in the summer of 2005, to the Volga Delta and Danube Delta in the fall of 2005, to the Nile Delta at the end of 2005). It was in a healthy grebe at Chany Lake in the summer of 2005 and a healthy teal in the Nile Delta, at then end of 2005, all involving the Qinghai strain. The Qiunghai strain has since spread to Europe, the Middle East, and Africa. Dozens of species (avian and mammalian) were involved and these countries were reporting H5N1 for the first time ever.

              The "debate" was really over in the summer of 2005 when Qinghai showed up at Chany Lake and Erhel Lake in healthy wild waterfowl.

              After that, it was all propaganda, which is still alive and well.
              Last edited by HenryN; August 10, 2007, 10:54 AM.

              Comment


              • #8
                Re: Ecologic Immunology of Avian Influenza (H5N1) in Migratory Birds

                For the record...
                According to the Nature article, the virus was first detected on April 30, 2005, in bar-headed geese at the lake.
                http://www.forbes.com/health/feeds/h...out526692.html
                Satellite tracking of bar-headed geese from India to Qinghai 2005:
                http://www.werc.usgs.gov/sattrack/project2005.html

                More info on Bar-headed geese here: http://www.flutrackers.com/forum/showthread.php?t=9963

                I don't know the incubation time estimates for birds with H5N1 (from infection > symptoms/illness > death/recovery), but estimates for humans range from 2-21 days.
                "In the beginning of change, the patriot is a scarce man (or woman https://flutrackers.com/forum/core/i...ilies/wink.png), and brave, and hated and scorned. When his cause succeeds, the timid join him, for it then costs nothing to be a patriot."- Mark TwainReason obeys itself; and ignorance submits to whatever is dictated to it. -Thomas Paine

                Comment


                • #9
                  Re: Ecologic Immunology of Avian Influenza (H5N1) in Migratory Birds

                  Originally posted by niman View Post
                  The "dead bird don't fly" argument was DOA. It never made any sense. In many instances, infected birds don't shed virus for several days. Initially they are healthy. Thus, one bird like a bar headed goose could fly 1000 miles before showing any symptoms. The bird could then die, but the H5N1 would already be at the new location, infecting more birds. It is like a relay race, The key is the location of the baton, not the condition of the runner after the baton has been passed.
                  [emphasis added]

                  I think it overstates the capacity of flu-infected birds to say that they are "healthy". They may not be shedding virus, but that's a different thing altogether, no? Research has shown that being infected with LPAI can hamper foraging and migratory performance:

                  "experiencing delayed migration, leaving their wintering site more than a month after uninfected animals...infected birds travelling shorter distances and fuelling and feeding at reduced rates. The data suggest that LPAI virus infections in wild migratory birds may have higher clinical and ecological impacts than previously recognised."

                  What are the effects on migratory performance of being infected with HPAI? We simply don't know. Dr. Niman presents information that is suggestive of wild birds (relayed or otherwise) transmitting the virus long distances; however, to imply that it is the only way of the virus getting from one place to another is disingenuous and dangerous, and only hampers our ability to understand the epidemiology of HPAI H5N1, which is more complex than both "dead birds don't fly" and "propaganda".

                  Comment


                  • #10
                    Re: Ecologic Immunology of Avian Influenza (H5N1) in Migratory Birds

                    Originally posted by canagica View Post
                    [emphasis added]

                    I think it overstates the capacity of flu-infected birds to say that they are "healthy". They may not be shedding virus, but that's a different thing altogether, no? Research has shown that being infected with LPAI can hamper foraging and migratory performance:

                    "experiencing delayed migration, leaving their wintering site more than a month after uninfected animals...infected birds travelling shorter distances and fuelling and feeding at reduced rates. The data suggest that LPAI virus infections in wild migratory birds may have higher clinical and ecological impacts than previously recognised."

                    What are the effects on migratory performance of being infected with HPAI? We simply don't know. Dr. Niman presents information that is suggestive of wild birds (relayed or otherwise) transmitting the virus long distances; however, to imply that it is the only way of the virus getting from one place to another is disingenuous and dangerous, and only hampers our ability to understand the epidemiology of HPAI H5N1, which is more complex than both "dead birds don't fly" and "propaganda".
                    Please. The propaganda campaign is quite intense.

                    Influenza is an infectious agent. Initially, the infected host will not have symptoms. Birds fly in flocks. They also share nature reserves.

                    The DATA clearly show the transmission and spread. At Qinghai Lake, all of the initial deaths were bar headed geese. By the time the OIE report was filed in May 2005, 5 species had been identified (two geese, two gulls, and comorants).

                    Fast forwarded to the summer of 2007 in Germany. Same scenario at Kelbra Lake. Initially all dead birds are black necked grebes, A couple of weeks later, multiple species are dead at Kelbra Lake. These are resident WILD birds dying in the middle of the summer. All have the Qinghai strain.

                    Prior to Qinghai Lake there were ZERO reports of Asian H5N1 in wild birds or domestic poultry west of China. Clade 1 was smuggled into Europe (found on plane in Belgium in 2004). Number of reported Clade 1 cases outside of southeast Asia in wild birds or domestic poultry = ZERO. Clade 2.3 was in quarantined exotic birds in England at beginnng of 2006. Number of clade 2.3 outbreaks in wild birds or domestic poultry outside of China/southeast Asia = ZERO.

                    ALL of the H5N1 west of China (wild birds or poultry) has been Qinghai (clade 2.2) and there have been HUNDREDS of reports in Europe, the Middle East, Africa (involving MULTIPLE introductions).

                    The DATA are VERY clear, as is the hand waving and propaganda (based on ZERO data).

                    Please cite DATA on anything but clade 2.2 in ANY wild bird or domestic poultry west of China if you expect comments to be taken seriously.

                    The "we don't know" in the wild birds debate really became obsolete in the summer of 2005. After that it moved well into the PROPAGANDA category, involving hopes and dreams (and ZERO data).

                    Real data rarely is this clean cut. There is ZERO doubt on the relative imporytance of wild birds and smuggling/trade in the long range spread of H5N1.

                    Comment


                    • #11
                      Re: Ecologic Immunology of Avian Influenza (H5N1) in Migratory Birds

                      Originally posted by niman View Post
                      Please. The propaganda campaign is quite intense.

                      The DATA clearly show the transmission and spread. At Qinghai Lake, all of the initial deaths were bar headed geese.

                      Fast forwarded to the summer of 2007 in Germany. Same scenario at Kelbra Lake. Initially all dead birds are black necked grebes, A couple of weeks later, multiple species are dead at Kelbra Lake. These are resident WILD birds dying in the middle of the summer. All have the Qinghai strain.

                      ALL of the H5N1 west of China (wild birds or poultry) has been Qinghai (clade 2.2) and there have been HUNDREDS of reports in Europe, the Middle East, Africa (involving MULTIPLE introductions).

                      The DATA are VERY clear, as is the hand waving and propaganda (based on ZERO data).

                      The "we don't know" in the wild birds debate really became obsolete in the summer of 2005. After that it moved well into the PROPAGANDA category, involving hopes and dreams (and ZERO data).

                      Real data rarely is this clean cut. There is ZERO doubt on the relative imporytance of wild birds and smuggling/trade in the long range spread of H5N1.
                      For clarification, the "we don't know" from my prior post referred to migratory performance in flu-infected wild birds. If we knew more about migratory performance in flu-infected birds, we would be better able to estimate the probability of risk. This is not PROPAGANDA, it's the SCIENTIFIC PROCESS, and to the best of my searching I have only found one reference that deals with the performance of wild migratory birds infected with avian flu.

                      In my last post I agreed that wild birds are playing a role (perhaps the only role?) but that there are potentially other factors at play. Suffolk-Hungary ring a bell? Where did the Hungarian H5N1 come from in the first place? For that matter, where did the H5N1 that killed all of the birds at Qinghai come from? No one mentions the bar-headed goose rearing farms on the shores of Qinghai Lake a possible source, but then again no one has published anything about those farms outside of anecdotal evidence (are they shut down? Was there disease there prior? Who knows!). Again, I can handwave about my opinions as much as anyone else in this forum, but I am interested in seeing the DATA, too.

                      The point of my last post seems to have been lost, which was that the epidemiology of HPAI H5N1 is complex, and focusing on any one agent gives an incomplete picture of limited usefulness. What we have are the known reported sequences of dead birds from outbreaks-that tells us where something has been found, and says something about transmission and spread. Is it the whole story? I don't think so. The issue of how it gets there (or stays there, in the potential case of an endemic reservoir in western Europe) is more complex, and arguably much more important.

                      It can't be passed off with a wave of the hands, or calling it propaganda. Why couldn't a more local source of this year's European H5N1 come from lax biosecurity in Hungary spread to the 4 winds by regional/local movements of birds/poultry/poultry products near the plant? It worked for getting the virus to the UK. I'll concede it unlikely, but is there any data to say otherwise?

                      The thing I want to know is how much less likely is it?: what proportion of migrants/residents seem capable of carrying/spreading the virus, how long can the virus persist/spread in water/feces/poorly vaccinated poultry, how the virus affects the migratory performance of symptomatic and asymptomatic carriers. How often are poultry/poultry products shipped west from Asia? From what regions do they come? What biosecurity measures are in place? How many birds die along the way? How are they disposed? The argument that all H5N1 west of China is Qinghai, and Qinghai has been found in wild birds, does not transitively mean that Qinghai can only be found in/dispersed by wild birds. To think that there is a clear picture of both the poultry and smuggling side of things is a bit naive.

                      These are the questions that would allow someone to judge the relative importance of the role of wild migratory birds in the dispersal/spread/persistence of H5N1. Without these answers, interpretation of the sequences involves some degree of handwaving and propaganda as well. Furthermore, if there were ZERO doubt in the scientific community then this paper wouldn't have been published.

                      Or I guess they could be completely convinced, and that instead of doubt, it IS a propaganda conspiracy by all of those rich, ignorant conservation organizations and scientists against those poor poultry companies ...

                      Comment


                      • #12
                        Re: Ecologic Immunology of Avian Influenza (H5N1) in Migratory Birds

                        The movement of H5N1 into long range migratory birds, followed by spread via those birds into at least 50 countries west of China is without doubt. The paper at the start of this thread tried to cast doubt, with a story that was charitably called propaganda. It really was utter nonsense. It started with a straw man invoking transport and transmission by asymptomatic birds, when it fact asymptomatic birds are not required, because even fatal infections begin with asymptomatic birds and the key is the movement of the H5N1, not the ultimate fate of the infected birds.

                        The other issues brought up on this thread are pretty tangential, and support is limited to hand-waving. The origin of the H5N1 at Qinghai Lake is really not an issue, although citing duck farm without evidence of sick birds, H5N1 infections, or Qinghai H5N1 infections is not much different than Martians or Al Queda. All are possible, but not very likely.

                        Sequences of H5N1 in wild birds in Jiangxi are close to Qinghai (have the same HA cleavage site but lack PB2 E627K) and are better candidates for a Qinghai H5N1 origin, as is H5N1 in India. All of the initial Qinghai cases were in bar-headed geese, which winter in northern India.

                        India is largely in denial. Poultry workers had H5N1 antibodies as early as 2002 and India maintains that there was no H5N1 in northern India at the beginning of 2006 (when 2005 infected bar-headed geese would return) or 2007 (when 2006 infected bar headed geese would return), and sequences from the isolates they do acknowledged suggest MUCH more H5N1 than reported.

                        As far as more info on wild birds is concerned, the existing data is quite extensive. Well over 2 dozen wild bird species have been identified, and the major current outbreak in central Germany in the middle of the summer STRONGLY suggests H5N1 is now endemic (there is no reason to assume resident wild birds were not infected in 2005, 2006, and 2007), and culling of domestic poultry in a small number of farms in Europe really doesn't impact the wild bird reservoir),

                        The transmission and transport of Qinghai H5N1 by wild birds is a VERY straightforward story, propaganda pieces based on hand waving, not withstanding.
                        Last edited by Niko; August 11, 2007, 05:13 PM. Reason: no content edited

                        Comment


                        • #13
                          Re: Ecologic Immunology of Avian Influenza (H5N1) in Migratory Birds

                          I interrupt my vacation to pose a challenge to Dr. Niman. Please develop a scenario based on accepted evidence from the peer-reviewed literature about stopover ecology, flight physiology, migratory pathways, reasonable timing, wildlife disease ecology etc. that can explain the spread of H5N1 from Asia to Europe. Please base as many statements as possible on literature references. So for example, it it will not be enough to state that a grebe or some other species was found to be asymptomatically infected with the virus. Based on age and sex of the individual, the time of year it was found and where it has been found a reasonable guess needs to be made if the bird is in fact migratory, where it was coming from and where it is likely to go to. Is it likely that the bird actually has made a long migratory flight? To find a virus in a wild bird is simply not enough.

                          There's absolutely no propaganda in the article which started this thread. It doesn't actually say that wild birds are absolutely blameless. It just reviews the state of knowledge in ecological immunology and claims that this knowledge makes it unlikely, but not impossible, that migratory movements are responsible for the long distance spread of H5N1. Dr. Niman hasn't countered convincingly any pertinent point made in this article. I am looking forward to an answer to my challenge.
                          Last edited by sharon sanders; August 17, 2007, 04:29 PM. Reason: sarcastic comment in reference to Niman - 1st warning

                          Comment


                          • #14
                            Re: Ecologic Immunology of Avian Influenza (H5N1) in Migratory Birds

                            Is it likely that the bird actually has made a long migratory flight?
                            I don't assume that one infected bird traveled the entire distance like the rest of it's flock. Dr. Niman's example of a relay race is reasonable to me. I can visualize brids, e.g., bar-tailed godwit, starting at New Zealand, stopping at various wetlands along the SE Asian coast to rest and replenish energy stores, while also passing on AI germs.

                            Our scientists at Univ. of Alaska, Fairbanks, explain the lower rate (1/2 of international rate) of Alaskan migratory bird AI by saying that some birds making longer migrations with fewer stopovers successfully migrate by shutting off their immune system to conserve energy. If they're correct, then birds with less strenuous migrations and intact immune systems, should be able to survive some potentially lethal strains of AI.

                            .
                            "The next major advancement in the health of American people will be determined by what the individual is willing to do for himself"-- John Knowles, Former President of the Rockefeller Foundation

                            Comment


                            • #15
                              Re: Ecologic Immunology of Avian Influenza (H5N1) in Migratory Birds

                              Originally posted by tompe View Post
                              I interrupt my vacation to pose a challenge to Dr. Niman. Please develop a scenario based on accepted evidence from the peer-reviewed literature about stopover ecology, flight physiology, migratory pathways, reasonable timing, wildlife disease ecology etc. that can explain the spread of H5N1 from Asia to Europe. Please base as many statements as possible on literature references. So for example, it it will not be enough to state that a grebe or some other species was found to be asymptomatically infected with the virus. Based on age and sex of the individual, the time of year it was found and where it has been found a reasonable guess needs to be made if the bird is in fact migratory, where it was coming from and where it is likely to go to. Is it likely that the bird actually has made a long migratory flight? To find a virus in a wild bird is simply not enough.

                              There's absolutely no propaganda in the article which started this thread. It doesn't actually say that wild birds are absolutely blameless. It just reviews the state of knowledge in ecological immunology and claims that this knowledge makes it unlikely, but not impossible, that migratory movements are responsible for the long distance spread of H5N1. Dr. Niman hasn't countered convincingly any pertinent point made in this article. I am looking forward to an answer to my challenge.
                              Please. H5N1 has spread to over 50 coubntries west of China after H5N1 moved into the long range migratory bird population at Qinghai Lake in May, 2005. After that it appeared in nature reserve after nature reserve in wild birds (waterfowl) at Chaney Lake, Erhel Lake, Volga Delta, Danube Delta, and Nile Delta )all of teh above in 2005). All were the Qinghai strain (and none of these countries had EVER reported Asian H5N1 previously) and the data has been verified in multiple peer reviewed articles.

                              Please, no more nonsense. It is 2007 and the debate on dead birds flying is over.
                              Last edited by sharon sanders; August 17, 2007, 04:30 PM. Reason: edited quote as referenced above

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