St. Louis Encephalitis (SLE) is closely related to West Nile virus and is transmitted by the same mosquito species. Mosquitoes become infected by feeding on birds infected with SLE.
The virus grows both in the infected mosquito and the infected bird, but does not make either one sick. You cannot get the virus from other people, birds or insects other than mosquitoes. SLE was first reported in humans in Virginia in 1975 and a total of 13 cases have been reported in Virginia to date.