Western Equine and St. Louis Encephalitis

Abstract

Data obtained during the first 18 months of a neurological follow-up study of Western equine and St. Louis encephalitis indicate that possibly as many as 32% will have some type and degree of sequelae at some time following the acute illness. Sequelae observed vary from mild emotional disturbances to severe neurologic damage. To date few residuals have arisen after a period of apparent recovery although it is too early for conclusive evidence on this point. Most patients with sequelae following the acute attack tended to improve with time. Sequelae were more frequent and more severe in younger patients, especially those who became ill before 3 months of age, and particularly if convulsions were a part of the acute illness. Severe sequelae in adults were infrequent. There is no evidence to date that either Western equine or St. Louis encephalitis produces parkinsonism.