California encephalitis, arthropod-borne encephalitis or encephalomeningitis, induced by an arbovirus. Infection usually is caused by a mosquito bite. Epidemics occur mainly in the Midwest, on the eastern seaboard, and in Texas and Louisiana. The virus was first isolated in California. See also arbovirus, encephalitis. ▪ OBSERVATIONS: The infection generally follows one of two clinical courses. The mild form is characterized by headache, malaise, gastrointestinal symptoms, and a fever that may reach 104° F. The more severe form may be marked by a sudden onset of fever, vomiting, headaches, lethargy, and signs of neurological involvement such as loss of reflexes, disorientation, seizure, loss of consciousness, and flaccid paralysis. ▪ INTERVENTIONS: Treatment usually involves administration of anticonvulsant and sedative medications. ▪ PATIENT CARE CONSIDERATIONS: Recovery usually begins in 1 week. Mortality rate is very low, but a significant number of patients have neurological sequelae for 1 year or more.
