A Continuing Study of the Acquisition of Natural Immunity to Poliomyelitis in Representative Louisiana Households

Abstract

Since 1953, about 150 households from 3 areas in southern Louisiana were observed to determine when and under what circumstances sub-clinical immunizing infections with polio-viruses occur. Routine monthly stool and blood specimens have revealed 109 episodes of household infection. Infections, with the 3 virus types, occurred throughout the year, but with marked seasonal increase in late summer and fall. Infections were more frequent in Negroes than in whites, and in large family groups. Infection characteristically involved all non-immune members of the index family as well as closely associated families. In 1954, type 3 infections predominated, and in 1955 type 1 infections were more frequent, both "epidemics" apparently conditioned by specific deficiencies in immunity among children under 4 years of age.