Clinical Characteristics of the 2019 Eastern Equine Encephalitis Outbreak in Michigan.

Background: Eastern equine encephalitis virus is a mosquito-borne alphavirus responsible for unpredictable outbreaks of severe neurologic disease in animals and humans. While most human infections are asymptomatic or clinically nonspecific, a minority of patients develops encephalitic disease, a devastating illness with a mortality rate of ≥30%. No treatments are known to be effective.