Diphtheria outbreak in Lao People's Democratic Republic, 2012-2013.

Abstract Background Diphtheria is a vaccine-preventable disease. When vaccination coverage and population immunity are low, outbreaks can occur. We investigated a diphtheria outbreak in Lao People’s Democratic Republic that occurred during 2012–2013 and highlighted challenges in immunization services delivery to children in the country. Methods We reviewed diphtheria surveillance data from April 1, 2012–May 31, 2013. A diphtheria case was defined as a respiratory illness consisting of pharyngitis, tonsillitis, or laryngitis, and an adherent tonsillar or nasopharyngeal pseudomembrane. To identify potential risk factors for diphtheria, we conducted a retrospective case-control study with two aged-matched neighborhood controls per case-patient in Houaphan Province, using bivariate analysis to calculate matched odds ratio (mOR) with 95% confidence intervals (CI). Reasons for non-vaccination among unvaccinated persons were assessed. Results Sixty-two clinical cases of diphtheria and 12 diphtheria-related deaths were reported in seven of 17 provinces. Among case-patients, 43 (69%) were Conclusion Suboptimal DTP3 coverage likely caused the outbreak. To prevent continued outbreaks, access to routine immunization services should be strengthened, outreach visits need to be increased, and missed opportunities need to be minimized. In the short term, to rapidly increase population immunity, three rounds of DTP immunization campaign should be completed, targeting children aged 0–14 years in affected provinces.