The epidemiology of St. Louis encephalitis in Corpus Christi, Texas, 1966

In the summer of 1966, an epidemic of St. Louis encephalitis occurred in Corpus Christi, Texas, coincident with one occurring in Dallas about 563 km to the north. Among the 76 cases confirmed in Corpus Christi, there were two deaths; the attack rate was 41.0 per 100,000. In contrast with a concurrent outbreak in Dallas and the 1964 outbreak in Houston, attack rates were much higher in populations of the upper socioeconomic districts. This distribution may have resulted from the combined effects of an unusual concentration of vector mosquito breeding sites in storm sewers in the upper socioeconomic districts and a higher degree of residual immunity in the residents of the lower socioeconomic areas.