A diphtheria outbreak in Dade County, Florida.

During a 16-week period in late 1969, 11 cases of diphtheria (three fatal) were reported from Miami, Dade County, Florida. For each of ten previous years, two cases at most had been reported. All patients resided in a predominantly black, low socioeconomic community within the 7-square-mile Model City area. Nine patients had positive cultures for toxigenic Corynebacterium diphtheriae, mitis strain. None of the 11 patients or 22 culture-positive household contacts had been vaccinated against diphtheria. During the outbreak, one dose of diphtheria-tetanus-pertussis vaccine or tetanus-diphtheria toxoid was given to more than 90,000 residents of Model City (95%) and to more than 200,000 residents of Dade County (16%). A state law was passed in June 1971 requiring all children to be vaccinated before entering school. No subsequent cases of diphtheria were reported in the ensuing five-year period. The Miami experience suggests that prompt mass vaccination will abort the spread of epidemic diphtheria and emphasizes the need for routine vaccination to minimize morbidity and mortality.