Ethological risk factors of West Nile infection on Wild birds in Senegal

Chevalier, Véronique; Reynaud, Pierre; Lefrançois, Thierry; Lancelot, Renaud; Baillon, François; Gaidet, Nicolas; Balança, Gilles; Sylla, S.

Ethological risk factors of West Nile infection on Wild birds in Senegal

2006

Serological studies performed in 2003, as well as viral isolations demonstrated that West Nile fever (WNF) was endemic in Senegal (West Africa). Large populations of potentially infected birds fly each year from West Africa to Europe. The goal of this study was to identify potential reservoirs of West Nile virus among Senegalese birds and ethological features related to WN infection. ln October 2003, wild birds were trapped and sampled in two different locations: the Ornithological Djoud'j National Park, located in the Senegal River Basin and in a village located in the Ferio area (northem Senegal). Sera were analysed using an inhibition immunocapture enzyme-linked immunosorbent assay. Serological data were analysed using a generalized linear Poisson model. Seven ecological features that may influence the exposure of birds to mosquito bites were included as explanatory variables: the trapping location, the migrating status, the feeding site, the resting site, the nesting type, the herd instinct level, and affinity with urban areas. A total of 422 birds representing 49 species were trapped and sampled. The overall prevalence rate was 5.5%. Resident birds building platform or cup nests, as well as birds feeding on soil or having low urban areas affinity were more at risk than others (p=0.01, p=0.02 and p=0.02 respectively). Potential consequences of these results on virus dissemination and WN reservoir birds are discussed. (Résumé d'auteur)

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