During 1991, state and local health departments reported 122 cases of human arboviral encephalitis to CDC. More than half (69) of the cases resulted from outbreaks of St. Louis encephalitis (SLE) in Arkansas and Texas. In addition, an epizootic of eastern equine encephalitis (EEE) extending from the Atlantic and Gulf coasts into the upper midwest caused sporadic human cases and a substantial loss of livestock. This report summarizes the reported cases of arboviral encephalitis in the United States during 1991 and underscores the continuing need for arbovirus surveillance and control.
