Enhanced arboviral transmission by mosquitoes that concurrently ingested microfilariae

Infection, dissemination, and transmission of an arbovirus in mosquitoes are enhanced by concurrent ingestion of microfilariae. Ingestion of Rift Valley fever virus alone infected only 64 percent of female Aedes taeniorhynchus. Of these, only 5 percent of refeeding mosquitoes actually transmitted virus. In contrast, ingestion of the same amount of virus from concurrently microfilaremic (Brugia malayi) gerbils resulted in 88 percent infection and 31 percent transmission. Enhanced transmission of virus may be attributed to increased transit of virus across the midgut wall. Endemic filariasis may promote arbovirus transmission in nature.