LACV is passed from the female mosquito to the eggs she lays. The virus can survive in dormant eggs through the winter and develop into infected, flying mosquitoes in the spring. Humans are dead end hosts of LACV while small rodents are amplifying hosts. Asymptomatic infections are not uncommon, but symptoms including fever, headache, fatigue, lethargy, and nausea and vomiting often manifest five to 15 days post infection. While uncommon, severe cases demonstrate with seizures and other neurological impairments and are seen most frequently in children. The case fatality rate for La Crosse is less than one percent. No vaccine for LACV currently exists and treatment is symptomatic. Severe cases may need hospitalization.