Children under the age of 16 seem to be most vulnerable. Milder symptoms include high fever, headache, stiff neck, and nausea. Death occurs in fewer than 1 percent of known cases. The illness was first identified in LaCrosse, Wisconsin in 1963. Unlike some of the other arboviruses, the LaCrosse virus can be passed from female mosquitoes to their offspring.
Most infections are mild, but severe illnesses can cause meningitis.
Infections are most serious in the elderly. Brief History St. Louis encephalitis was first detected in the city after which it is named in 1939. Margaret Smith, an assistant professor of pathology in Washington University, first identified the sickness as viral. Since then, St. Louis encephalitis has emerged as the most common arbovirus in the United States. This document has been assembled to give information to the public and is for informational purposes only.