A Case-Control Study for Diphtheria in East Java, Indonesia, 2012
Background: Diphtheria, caused by toxigenic Corynebacterium diphtheriae, is an upper respiratory tract illness characterized by sore throat, low-grade fever, and an adherent pseudomembrane over the tonsils, pharynx and/or nasal cavity. Since 2010, the East Java provincial health department reported a rise in diphtheria cases. From January-September 2012, 500 cases were reported and 53 were laboratory-confirmed by culture for toxigenic C. diphtheriae. In November 2012, the MOH and FETP Indonesia conducted a case-control study to identify risk factors for diphtheria in East Java.
Method: We reviewed the East Java provincial surveillance database and identified 39 laboratory culture-confirmed cases from 6 districts during January-September, 2012. Two age-matched neighbourhood controls were recruited per case. Information collected on participants using pretested questionnaires during household interviews included demographic characteristics, travel history, and vaccination status with a diphtheria-containing vaccine (DCV). We estimated mOR and 95% CI using multivariate conditional logistic regression.
Result: Thirty-seven cases and 74 controls were enrolled, median age was 9 years. The multivariate model included vaccination status, DCV doses received, household size, recent travel, years living at current residence, and number of children aged 7 members had increased risk compared with households having ≤3 members (mOR:27.9; 95% CI:1.7–461.9).
Conclusion: Vaccination with any dose of DCV was protective against diphtheria but ≥3 doses had the greatest effect. Prevention efforts should focus on strengthening delivery of routine immunizations.
Key words: diphtheria, outbreaks, case control study