Laboratory studies on the vector capability of Aedes (neomelaniconion) unidentatus McIntosh and Aedes (Aedimorphus/ dentatus (Theobald) with West Nile and Sindbis viruses

Abstract

Laboratory tests were made with Aedes (Neomelaniconion) unidentatus McIntosh and Aedes (Aedimorphus) dentatus (Theobald) collected from the Highveld region of the Transvaal, South Africa, to determine their ability of transmit West Nile and Sindbis viruses. Viraemic hamsters or a viraemic chick were exposed to the mosquitoes as infective meals. Infection of mosquitoes was determined by testing mosquitoes individually for the presence of virus 10-26 days later. Transmission of virus, attempted between the 10-20th days by exposing hamsters to groups of mosquitoes, was not achieved. With West Nile virus, the high concentrations of virus required to infect each species led to the conclusion that neither is an important vector of this virus. With Sindbis virus and A. unidentatus the 10 per cent infection threshold was less than 2,6 logs of virus, while with A. dentatus it was about 3,5 logs. This suggests that both species, but more particularly A. unidentatus, could be vectors of this virus.