The isolation, from pools of mosquitoes in Nigeria, and the identification, of strains of Bunyamwera, of Pongola, and of Chikungunya viruses are described. The last two are new isolations for Nigeria.
Most of the isolations were from Mansonia africana, the dominant mosquito species in the area investigated, but other species of mosquito are probably involved in their cycle of transmission. Aedes aegypti was readily infected with all the viruses in the laboratory.
Little is known about their natural cycles. Serological studies showed that monkeys may sometimes be involved, and this was supported by laboratory observation. Human infestion with all thse virus occurs in Southern Nigeria, with some regional variations.