Isolation of La Crosse, Cache Valley, and Potosi viruses from Aedes mosquitoes (Diptera: Culicidae) collected at used-tire sites in Illinois during 1994-1995.

Prospective studies were conducted at used-tire sites in Illinois during 1994-1995 in an effort to isolate arboviruses from mosquitoes, particularly Aedes albopictus (Skuse) and Aedes triseriatus (Say). Three isolates of Potosi virus were obtained from Ae. albopictus collected at a waste tire site in Jasper County during 1994 and 1995. Also, a single isolate of Cache Valley virus was obtained from Ae. albopictus collected at the Jasper County site during 1995. These are the first records of arbovirus isolations from Ae. albopictus in Illinois and the first isolate of Cache Valley virus from this mosquito species. During 1994, two isolates of La Crosse virus were made from Ae. triseriatus collected at a used-tire site in Peoria County in proximity to the residence of a human La Crosse encephalitis case. This is the first evidence in Illinois that indicates increased risk to humans living near used-tire sites, which may serve as foci for production of Ae. triseriatus, the vector of La Crosse virus. Tire removal and improved environmental sanitation at such sites may greatly reduce the abundance of vector mosquitoes, and, therefore, the risk of arbovirus transmission.