[Persistence of an endemic circulation of the West Nile virus in Madagascar].

The wide geographic distribution of the West Nile virus and the increase in virulence observed since 1994 in the Mediterranean basin, central Europe and North America, with several outbreaks of lethal encephalitis, demonstrate the importance of regular surveillance of the epidemiological data regarding this virus in the world. The Institut Pasteur de Madagascar has shown between 1975 and 1990 that this arbovirus was most abundant in Madagascar, where it had an endemic circulation. There has been no further study since that time. In order to evaluate the level of circulation, the seroprevalence of anti-West Nile antibodies in children that are 15 or less was measured on two different collections of sera. These collections came from population studies realised respectively in the region of Ambositra in the Highlands in 1996 and in the city of Mahajanga on the north west coast in 1999. The seroprevalence were 2.1% and 10.6% respectively, these results indicate that the circulation of this climatic dependent virus is still significant.