POLIOMYELITIS IN DES MOINES, IOWA, 1959: THE INFLUENCE OF SALK VACCINATION ON THE EPIDEMIC PATTERN AND THE SPREAD OF THE VIRUS IN THE COMMUNITY12

Abstract

This major epidemic occurred in Des Moines and the surrounding areas of Polk County, Iowa. Of the 174 cases reported in Polk County, 135 were in Des Moines. There were 4 deaths. The attack rates were highest among the Negro and low-income white families. A preponderance of cases were in unvaccinated children of preschool age. The epidemic had 2 peaks, one in late June and the other in late August. Etiologic studies indicated that the 1st part of the epidemic was caused by poloivirus type 1; the 2nd part was associated with both poloivirus type and other enteroviruses. Of the 97 agents isolated from 149 patients, 86 were polivirus type 1. The other agents consisted of 2 Coxsackie B virus type 2, 2 ECHO virus type 7, and 7 unidentified. All the 11 nonpolioviruses were isolated in the latter half of the epidemic. Salk vaccine was estimated to be 80% effective in preventing paralytic poliomyelitis. The study also suggests that high levels of vaccination might have an influence on limiting the spread of poliovirus in the community.