EPIDEMIOLOGIC ASPECTS OF A ST-LOUIS ENCEPHALITIS OUTBREAK IN FORT-WALTON BEACH, FLORIDA IN 1980

From July 10 through August 4, 1980, five cases of St. Louis encephali tis (SLE) occurred in and near Fort Walton Beach on the Gulf Coast of northwest Florida. These were the first cases of SLE ever reported fro m the Florida panhandle. To determine the extent of SLE infection in t he community, sera (n = 968) were collected from patients at the local hospital and county public health unit and tested for SLE virus antib ody. The SLE attack rate was highest in a centrally located impoverish ed census tract. There was a trend toward decreasing seroprevalence wi th distance from the central area of the city. Overall, seroprevalence was higher in males (prevalence ratio = 2.7) and in all areas, seropr evalence increased with age. The serosurvey results suggest that SLE h as been endemic in the Fort Walton Beach area.