Transmission of Ockelbo virus by Aedes cinereus, Ae. communis, and Ae. excrucians (Diptera: Culicidae) collected in an enzootic area in central Sweden.

Studies were conducted to determine the ability of Aedes excrucians (Walker), Ae. cinereus Meigen, and Ae. communis (De Geer) group mosquitoes, collected in an Ockelbo (OCK) virus enzootic area in central Sweden, to transmit this virus. All three species were highly susceptible to infection; at least 96% of the specimens of each species became infected after ingesting blood from a viremic chicken. Recovery of virus from the legs of all 61 of the Ae. excrucians and from 51% (24 of 47) and 75% (6 of 8) of the Ae. cinereus and Ae. communis tested, respectively, indicated that OCK virus readily disseminated from the midgut to the hemocoel in these species. Although none of the Ae. communis refed, Ae. cinereus and Ae. excrucians successfully transmitted OCK virus by bite. Because these Aedes species are attracted to avian and mammalian hosts and because OCK virus has been isolated from field-collected specimens in Sweden and the USSR, Aedes mosquitoes should be considered a possible link between human infections and the enzootic cycle involving birds and Culex and Culiseta mosquitoes.