Predicting West Nile virus seroprevalence in wild birds in Senegal.

West Nile fever epidemiology is complex, and the role of birds in the maintenance, amplification, and dissemination of the West Nile virus (WNV) remains partially unknown. In 2003, a serological study was performed in Senegal, where West Nile infection is considered endemic. The goal was to identify potential reservoirs of WNV among bird species present in the Ferlo area (northern Senegal) and the Senegal River Valley, and to screen the ecological factors possibly related to West Nile infection. Serological data were analyzed using a generalized linear model. Statistical association between ecological factors and the risk of infection were then modeled to derive a species-specific risk. A cross-validation was conducted. The overall observed prevalence rate was 5.5% (n = 422). Thirteen bird species were found positive, from which five were migrating: Lanius senator, Anthus trivialis, Hippolais opaca, Jynx torquilla, and Cercotrichas galactotes. The nesting type in resident birds was positively correlated with the risk of infection (odds ratio [OR] = 11, p = 0.0003); the gregariousness level of birds appeared as a protective factor (OR = 0.3, p = 0.01). The predicted prevalence varied between 1% and 39% for resident species and between 1% and 7% for migrating species. Results of model internal validation were satisfactory at the individual and species level. However, more field and experimental investigations are needed to confirm these preliminary results and help target the future research and surveillance in Senegal.

What are African monarchs (Aves, Passeriformes)? A phylogenetic analysis of mitochondrial genes.

We address the phylogenetic relationships of ten passerine bird species representing the five presently supposed monarchine (family Monarchidae) genera (Terpsiphone, Hypothymis, Elminia, Trochocercus, Erythrocercus) from Asia and Africa, as well as three monarchs from Australasia, three representatives of the related genera Rhipidura and Dicrurus, and 20 representatives of 11 other oscine groups (including two Culicicapa flycatchers) and one sub-oscine, using two partial mitochondrial genes (cytochrome b and large sub-unit ribosomal 16S RNA). Molecular data corroborate ecological, ethological and morphological observations on the probable heterogeneity of Trochocercus and indicate that this genus is polyphyletic; two of its species are members of Monarchidae allied to Terpsiphone and Hypothymis; the others are more closely related to Elminia. Elminia is not a member of Monarchidae and is not related to any other sampled species, except Culicicapa. Erythrocercus is also outside the Monarchidae but inside a Sylvii-Pycnonotidae group. These results point once more to the need of a fully revised phylogeny of passerine birds.