Epidemiological features of an outbreak of diphtheria and its control with diphtheria toxoid immunization.

An outbreak of diphtheria primarily involving adults occurred in seven townships and one farm in Jiangling county, Hubei, China from September 1988 to January 1989. Of the 103 reported cases, 80 were aged over 16 years, and there were two deaths. One hundred cases were reported in Jingzhou and its surrounding townships, only three occurred in townships distant from Jingzhou. The incidence and case fatality rates were 11.54/100,000 and 1.94% respectively. Twenty-one strains of diphtheria bacillus were isolated from 68 patients. A special immunization programme using adsorbed diphtheria toxoid was conducted 1 month into the outbreak, following which the incidence declined rapidly. Five vaccinees subsequently developed diphtheria.