Arthropod-Borne Encephalitis in the United States, 1957

Abstract

ENCEPHALITIS virus activity decreased in 1957, according to reports from epidemiologists of 46 States to the Communicable Disease Center, Public Health Service. Eastern encephalitis (EE) epizootics occurred in the Gulf States and as far north as South Carolina, but only five confirmed human cases came to our attention: two in Florida and three in Louisiana (fig. 1). Minimal virus activity was recorded in New Jersey and Massachusetts. Western encephalitis (WE) virus activity was prominent only in the Mountain States in 1957, with California and Texas registering few cases (fig. 1). The majority of the reported human cases were centered about a small outbreak in the Denver, Colo., area. The major public health problem in 1957 am.ong the arthropod-borne diseases in the United States continued to be St. Louis encephalitis (SLE), with the bulk of cases in Texas and California (fig. 1). Florida registered its first proved case, the only geographic extension of the North American arthropodborne encephalitides beyond previous historical limits (1). The sizable outbreak of SLE occurring in the lower Rio Grande Valley appears to be the only major concentration of human cases of encephalitis in 1957.