Transmission of Venezuelan encephalitis virus by naturally infected Culex (Melanoconion) opisthopus.

During August 1977 two of 975 Culex (Melanoconion) opisthopus collected from an enzootic marsh habitat on the Pacific coast of Guatemala transmitted VE virus to hamsters. Eight VE strains were isolated from Cu. opisthopus. The minimal level of VE infection in this species during July-August 1977 at La Avellana, Guatemala was 1/128 (8/1,021), and the prevalence of Cu. (Mel.) opisthopus transmitting VE virus was 1/487 (2/975). This mosquito was the predominant species attacking humans at that time, suggesting that Cu. opisthopus is a vector of VE virus to man as well as a vector in enzootic cycles in Guatemala. These studies establish Cu. opisthopus as the third proven enzootic vector of VE virus.