RiftValley fever virus (family Bunyaviridae, genusPhlebovirus). Isolations fromDiptera collected during aninter-epizootic period inKenya

SUMMARY Atotal of134876Diptera collected inKenyaduring a3-year period weretested in3383pools forRiftValley fever(RVF)virus. Nineteen pools ofunengorged mosquitoes werefoundpositive forRVF.Allisolations weremadefromspecimens collected atornearthenaturally orartificially flooded grassland depressions that serve asthedevelopmental sites fortheimmature stages ofmanymosquito species. Theisolation ofvirusfromadultmaleandfemale A.lineatopennis whichhad beenreared fromfield-collected larvae andpupaesuggests thattransovarial transmission ofthevirus occurs inthis species.