California encephalitis virus causes subacute encephalomyelitis in an adult

A 24-year-old man from rural Mississippi had a case of California encephalitis (CE) that evolved as a subacute encephalomyelitis. The incidence of CE in adults is low, especially in the southeastern United States, and to our knowledge the clinical profile of symptomatic disease in adults has not been established. The characteristics of CE and St Louis encephalitis, the usual cause of arboviral illness affecting adults in the Southeast, differ.