Diphtheria: a possible foodborne outbreak in Hodeida, Yemen Arab Republic.

Between 29 August 1981 and 16 January 1982, an epidemic of diphtheria produced 149 cases in Hodeida, Yemen Arab Republic. The overall attack rate was 11.8 per 10 000; the most frequent victims were males under 5 years of age, with an attack rate of 55.7 per 10 000. Severity of the illness varied inversely with age and the number of previous doses of DPT. A case-control study showed that vaccination with DPT was protective (P = 0.03) with an efficacy of 87.3% (95% confidence interval, 32.2-99.5%) among those who had received 3 or more doses. Risk factors for the development of disease were previous contact with a case (P = 0.002), previous contact with a person having skin disease (P = 0.04), obtaining drinking-water from a wheeled carrier (P = 0.008), and consumption of factory-made yoghurt (P = 0.003). The secondary attack rate among household contacts under 15 years of age was at least 1.3%.