The potential distance of highly pathogenic avian influenza virus dispersal by mallard, common teal and Eurasian pochard.

Waterbirds represent the major natural reservoir for low pathogenic (LP) avian influenza viruses (AIV). Among the wide diversity of subtypes that have been described, two of them (H5 and H7) may become highly pathogenic (HP) after their introduction into domestic bird populations and cause severe outbreaks, as is the case for HP H5N1 in South-Eastern Asia. Recent experimental studies demonstrated that HP H5N1 AIV infection in ducks does not necessarily have significant pathological effects. These results suggest that wild migratory ducks may asymptomatically carry HP AIV and potentially spread viruses over large geographical distances. In this study, we investigated the potential spreading distance of HP AIV by common teal (Anas crecca), mallard (A. platyrhynchos), and Eurasian pochard (Aythya ferina). Based on capture-mark-recapture method, we characterized their wintering movements from a western Mediterranean wetland (Camargue, South of France) and identified the potential distance and direction of virus dispersal. Such data may be crucial in determining higher-risk areas in the case of HP AIV infection detection in this major wintering quarter, and may serve as a valuable reference for virus outbreaks elsewhere.