Diphtheria in the Dominican Republic: reduction of cases following a large outbreak

Abstract

OBJECTIVE: To describe the most recent outbreak of diphtheria in the Dominican Republic and the disease's occurrence and vaccination coverage in 2004-2013. METHODS: Clinical data of diphtheria cases that occurred in 2004 and that met the study's case definition were reviewed along with socioeconomic and epidemiological information from the cases' families. Univariate and multivariate analyses were performed to assess risk factors for fatal diphtheria. Routine surveillance and vaccination coverage data are presented. RESULTS: From January 2004-April 2005, a total of 145 diphtheria cases were reported; 80 (66%) of the 122 cases reported in 2004 met the case definition; 26 were fatal (case-fatality rate: 32.5%). Incidence was highest in the group 1-4 years of age at 5.3 per 100 000; 62.5% were male. Of the 80 cases, 61 (76%) where hospitalized in Hospital A, 17 in Hospital B, and 2 in two other hospitals. Earlier onset (first half of 2004), birth order, and tracheotomy were associated with fatal diphtheria (P < 0.05); cases in Hospital A were also more likely to be fatal (P = 0.066). The average annual diphtheria incidence was 4.91 cases/1 million people in 2000-2003, climbed to 8.8 cases per million in 2004-2005, and dropped to 0.38 in 2006-2014; no diphtheria cases have been reported since 2011. DTP3 vaccination coverage ranged from 72%-81% in 2000-2004 and from 81%-89% in 2005-2013. CONCLUSIONS: The 2004-2005 diphtheria outbreak in the Dominican Republic resulted in important and avoidable morbidity and mortality. Annual cases declined and no cases have been reported in recent years. Maintaining high vaccination coverage and diligent surveillance are crucial to preventing diphtheria outbreaks and controlling the disease.

Keywords

• Diphtheria
• vaccination
• disease outbreaks
• Dominican Republic