Disease Name

Saint Louis Encephalitis

Vector Information

St. Louis encephalitis virus (SLEV) is an arbovirus in the genus Flavivirus. It is causes SLEV and is transmitted to humans through the bite of infected mosquitoes, which often acquire the virus from an infected bird. Prevention techniques center on avoiding mosquito bites and include use of Environmental Protection Agency-registered insect repellents, mosquito nets, wearing long-sleeved clothing, and controlling mosquito populations around the home. 

Humans and other mammals are dead end hosts of SLEV while birds are the reservoir host. More than 99% of viral infections are asymptomatic, but systemic symptoms including headache, dizziness, nausea, and malaise manifest in some cases. Where apparent, symptoms demonstrate five to 15 days post infection and often become progressively more severe over several weeks. Late-stage infections can result in confusion, disorientation, dizziness, tremors, coma, and death. Elderly individuals are most likely to demonstrate severe and encephalitic symptoms, and case fatality rates for symptomatic individuals are between five and 30 percent depending on age. There is no vaccine for SLEV and treatment is symptomatic. Severe cases often warrant hospitalization.