Prevalence and clinical features of epilepsy in a biracial United States population.

A need for prevalence information emphasizing racial differences prompted a door-to-door survey of all residents of Copiah County, Mississippi. The fieldwork involved a complete census and an extensive screening questionnaire inquiring about diagnoses, signs, and symptoms of neurologic disease. Residents who lived in institutions or had screening responses suggestive of epilepsy were requested to have an examination by neurologists who used defined diagnostic criteria. Prevalence day was 1 January 1978, and the survey yielded prevalence ratios of 1,043/100,000 inhabitants for epilepsy and 678/100,000 inhabitants for active epilepsy. Age-adjusted prevalence ratios were somewhat higher for males and for blacks. Of the 246 identified cases of epilepsy, 37% were judged symptomatic. The leading (putative) cause was head trauma, especially among white males. About 57% of the 246 cases had been evaluated previously by a neurologist or neurosurgeon, while 7% had never been evaluated medically before the survey.