The Camargue is an alluvial wetland covering some 140 000 ha in the Rhône delta (South of France). It is situated at the crossroads of numerous migratory routes of Palaearctic birds and is recognized as one of the main Mediterranean wintering area. Wild birds, and especially waterbirds in the Anseriformes and Charadriiformes orders, are considered to be the natural reservoir for avian influenza viruses (AIV). We combined population surveillance, molecular analysis and modeling in order to answer simple questions such as: which are the birds species involved in the transmission of AIV ? Does the highly pathogenic H5N1 circulated in the Camargue in winter 2005-2006, during its spread from Asia to Europe ? How does AIV transmission and persistence among wild birds occurs ?
Results/Conclusions
Since fall 2005, we sampled more than 5000 birds belonging to 112 different species. The level of infected birds is about 3% and concerns only waterbirds (ducks and gulls). We did not detected highly pathogenic H5N1 viruses. First results concerning subtyping of circulating AIV suggest possible cases of natural intercontinental exchanges and gene segment reassortment. We present here the first data on the global pattern of avian influenza viruses circulation among the wild bird communities present in the Camargue.
