Rise and fall of St. Louis Encephalitis Virus in Florida

Abstract

St. Louis encephalitis virus has had a fascinating history in Florida. The virus was introduced into the Miami area in the early 1950s. This introduction resulted in two human outbreaks, one in 1952 and a second in 1958. Three urban SLE epidemics were reported in the Tampa Bay area in 1959, 1961, and 1962. The virus virtually disappeared from the state until 1977 when a widespread rural SLE epidemic was reported in 20 Florida counties with 110 confirmed human cases. An almost identical rural SLE epidemic was reported in 1990 when 226 human SLE cases were reported in 28 Florida counties. Following the introduction of West Nile virus into Florida in 2001, reports of SLEV transmission to sentinel chickens and humans decreased dramatically. Except for a 2014 focal outbreak of two SLE cases in Duval County, only sporadic transmission of SLEV to humans and sentinel chickens was reported in the state between 1998 and 2022.