Birds are the reservoir host of WEEV while humans and other mammals are dead end hosts incapable of directly transmitting the disease since human blood virus levels are not high enough to directly infect a mosquito. Most infected individuals are asymptomatic, however symptoms including fever and headache can develop seven to 21 days post infection.Severe disease can develop in a small subset of people, primarily in the very old and young, and is demonstrated as encephalitis, delirium, disorientation, coma, paralysis, and death. Irreversible neurological damage can occur in infants and young children. The case fatality rate for WEEV infection overall is approximately four percent and between five and 15 percent for severe cases. Around half of infants with severe WEEV infection will experience irreversible brain damage. No vaccines for WEEV exist and treatment is symptomatic.