Oropouche virus. IV. Laboratory transmission by Culicoides paraensis.

Biological transmission of Oropouche (ORO) virus by Culicoides paraensis (Goeldi) has been successfully demonstrated in the laboratory. Adult Culicoides, collected in an area where ORO virus was absent, were infected by feeding on viremic hamsters and then periodically exposed to susceptible hamsters at specific intervals post-infectious blood meal. These C. paraensis were capable of biological transmission of the virus 4-9 days post-feeding on viremic hamsters circulating 6.7-9.9 log10SMLD50/ml virus. Infection rates of 54% and 80% were found for C. paraensis assayed 7 days post-feeding. Virus transmission rates for these experiments were 83% and 25%, respectively. No evidence of mechanical transmission of ORO virus by C. paraensis was observed when interrupted feeding of Culicoides on viremic hamsters was followed by feeding on susceptible hamsters.