The claim that migratory birds are responsible for the long-distance spread of Asian lineage highly pathogenic avian influenza viruses of the subtype H5N1 rests on the assumption that infected wild birds can remain asymptomatic and carry out long migratory flights unhampered. We critically assess this claim from the perspective of ecological immunology, a research field which analyses immune function in an ecological, physiological and evolutionary context. Long-distance migration is one of the most demanding activities in the animal world. We show that a number of 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. It remains, however, possible that infected, symptomatic wild birds can act as vectors over shorter distances, as appears to have occurred in Europe in early 2006.

WEBER Thomas;  STILIANAKIS Nikolaos; 

2007-08-07

CENTER DISEASE CONTROL

JRC37373

https://publications.jrc.ec.europa.eu/repository/handle/JRC37373,