The heterogeneity of measles epidemiology in India: implications for improving control measures.

摘要

BACKGROUND: Measles vaccination coverage varies in India. Trainees of the Field Epidemiology Training Programme (FETP) investigated 8 outbreaks from 2004 through 2006 in Himachal Pradesh, Uttaranchal, Tamil Nadu, and West Bengal. We reviewed these outbreaks to contribute to the description of the epidemiology of measles and propose recommendations for control. METHODS: FETP trainees searched for measles cases through stimulated passive surveillance or door-to-door case search; estimated attack rates, case fatality, and the median age of case patients; interviewed mothers about vaccination status of their children; and collected serum samples for immunoglobulin M serological testing whenever possible. For 3 outbreaks, the trainees estimated the vaccine efficacy for children >12 months of age through cohort studies. RESULTS: Six of the 8 outbreaks were serologically confirmed. Compared with outbreaks in other states, outbreaks in states with vaccination coverage of >90% had a higher median age among case patients and a lower median attack rate. Six deaths (case fatality rate, 1.5%) occurred during the 5 outbreaks for which vitamin A was not used. The vaccine efficacy was 84% (95% confidence interval [CI], 74%-91%) in Himachal Pradesh. In West Bengal, it was 66% (95% CI, 44%-80%) in 2005 and 81% (95% CI, 67%-89%) in 2006. CONCLUSIONS: In states with higher coverage, attack rates were lower and case patients were older. Although states with coverage of <90% should increase 1-dose coverage and address coverage in pockets that are poorly reached, a second opportunity for measles vaccination could be considered in states such as Himachal Pradesh and Tamil Nadu. Use of vitamin A for case management needs to be generalized.