Ecologic Immunology of Avian Influenza (H5N1) in Migratory Birds

European Commission's Joint Research Centre, Ispra, Italy.
Emerging infectious diseases (Impact Factor: 7.33). 09/2007; 13(8):1139-43. DOI: 10.3201/eid1308.070319
Source: PubMed

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.

  • Source
    12/2014, Degree: Habilitation à Diriger des Recherches, Supervisor: Ecole Doctorale SIBAGHE, Université Montpellier 2
  • [Show abstract] [Hide abstract]
    ABSTRACT: Environmental changes are simultaneously affecting parasitic diseases and animal migrations, making it important to understand the disease dynamics of migratory species, including their range of infections and investment into defences. There is an urgent need for such knowledge because migratory animals, especially birds, are important for pathogen transmission and also particularly sensitive to environmental changes. Here we compare the nematode species richness and relative immune investment (via relative spleen size) of almost 200 migratory and non-migratory species within three diverse groups of birds (Anseriformes, Accipitriformes and Turdidae) with worldwide distributions and varied ecology. Our results provide the first large-scale demonstration that migratory birds face greater challenge from macroparasites as they have significantly dissimilar nematode fauna and higher nematode species richness compared to non-migratory species. Even though birds with relatively large spleens had more nematode species, there was no difference in relative spleen size between migratory and non-migratory bird species. Th e physiological stress of migration can be exacerbated by the potential range of pathologies induced by their richer nematode communities, particularly in combination with environmental perturbations. Altered migration stemming from global changes can also have important consequences for nematode transmission.
    Oikos 11/2014; 124(4). DOI:10.1111/oik.01799 · 3.56 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: The spatial spread of the highly pathogenic avian influenza virus H5N1 and its long-term persistence in Asia have resulted in avian influenza panzootics and enormous economic losses in the poultry sector. However, an understanding of the regional long-distance transmission and seasonal patterns of the virus is still lacking. In this study, we present a phylogeographic approach to reconstruct the viral migration network. We show that within each wild fowl migratory flyway, the timing of H5N1 outbreaks and viral migrations are closely associated, but little viral transmission was observed between the flyways. The bird migration network is shown to better reflect the observed viral gene sequence data than other networks and contributes to seasonal H5N1 epidemics in local regions and its large-scale transmission along flyways. These findings have potentially far-reaching consequences, improving our understanding of how bird migration drives the periodic reemergence of H5N1 in Asia.
    Proceedings of the National Academy of Sciences 12/2014; 112(1). DOI:10.1073/pnas.1405216112 · 9.81 Impact Factor

Full-text (3 Sources)

Available from
May 15, 2014