Measles in rural West Bengal, India, 2005-6: low recourse to the public sector limits the use of vitamin A and the sensitivity of surveillance.

BACKGROUND: Measles is often underreported. We evaluated the sensitivity of the measles surveillance in 2 districts of West Bengal in 2005-2006. METHODS: We sampled households with children aged <5 years in village clusters selected with probability proportional to size. We searched households door to door to identify World Health Organization-defined suspected measles cases that had occurred during 12 months in 2004-2005 in Howrah and in 2006 in Purulia. We interviewed mothers about use of health care services during episodes and calculated the proportion of patients seen in the public sector. We reviewed surveillance records at all levels to estimate the proportion of cases seen in public health care facilities that had been reported to the district. We calculated the overall sensitivity of measles surveillance by multiplying these 2 proportions. RESULTS: In Howrah, we identified 240 cases of measles. Of these, 8 (3.3% [95% confidence interval {CI}, 1.5%-6.5%]) had been seen in public facilities and recorded. Of 980 cases identified in 448 public facilities in the periphery, 962 (98%) had been transmitted to the district (overall sensitivity of surveillance, 3.2%). In Purulia, we identified 167 measles cases. Of these, 39 (23.4% [95% CI, = 17.2%-30.5%]) had been seen in public facilities and recorded. Of 418 cases identified in public facilities in the periphery, 414 (99%) had been transmitted to the district (overall sensitivity of surveillance, 23.1%). CONCLUSIONS: Measles surveillance captured a minority of measles cases, but cases captured were transmitted well to the district. Surveillance must engage the private sector. Health education focusing on vitamin A treatment for measles might provide an incentive to seek care, which could increase the sensitivity of surveillance.

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

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.