Measles outbreak investigation at Indo-Myanmar border, Longding District, Arunachal Pradesh, India, 2017

Background: On May 23, 2017, the health authorities in Longding district, Arunachal Pradesh, India, reported four suspected measles-related deaths in Konsa village, a remote village on the Indo-Myanmar border. Objective: We investigated to describe the epidemiology of the outbreak and identify associated risk factors. Methods: We defined a measles case as fever and maculopapular rash with cough, coryza, or conjunctivitis in a village of Longding district resident from March 1 to June 18, 2017. In Konsa village, we conducted a retrospective cohort study of children <= 5 years. We calculated attack rate (AR), case fatality rate (CFR), measles-containing vaccine first dose (MCV1) and Vitamin A coverage, risk ratio (RR), and vaccine efficacy. We collected samples for laboratory confirmation. We conducted a routine immunization system evaluation at multiple levels of Longding district. Results: We identified 75 suspected cases (56% females) for a Konsa village-specific AR of 86% (75/87) among children <= 5 years; the median age was 36 months; CFR was 7% (5/75); all deaths unvaccinated; none received Vitamin A. Coverage for MCV1 was 9.2% (6/65) and Vitamin A 4.6% (3/65). No MCV1 (RR = 7.3, 95% confidence interval [CI] = 1.3-53) and participation in a recent local festival (RR = 5.3, 95% CI = 1.5-18.5) were associated with illness. MCV vaccine efficacy was 100%. Of 17 cases, 13 tested positive for measles. The local health facility had neither staff nor immunization microplans. Conclusions: This outbreak was likely due to low MCV1 and Vitamin A coverage due to poor health-care access. The investigation led to a district measles catch-up campaign and resumption of regular immunization.