Measles epidemiology and outbreak response immunization in a rural community in Peru

Only limited data are available on the impact of measles outbreak response immunization (ORI) in developing countries. We conducted a community survey in Espindola, a rural border community in northern Peru, following a measl es outbreak and subsequent ORI to study the epidemiology and impact of the outbreak and to evaluate the costs and benefits of measles ORI. During the outbreak, 150 of the 553 Espindola residents developed clinical cases of measles. Adults accounted for 44.0% of cases, and were frequently identified as primary cases. The attack rate among all susceptible people w as 45.5% and was highest (61.2%) for the 16-20 year age group. Among adults , significant risk factors for developing measles included being aged 16-20 years (relative risk [RR]=3.06, 95% CI = 2.08, 4.49) and being male (RR= 1 .73, 95% CI = 1.11, 2.71). Among serologically confirmed cases, 60.7% devel oped diarrhoea and 32.1% pneumonia. The overall case-fatality rate was 3.3% , but reached 19.1% in the 0-23-month age group. Failure to reach children through either routine immunization or national campaigns made this communi ty vulnerable to the severe and extensive impact of measles virus importati on. The ORI campaign targeted non-measles case children aged 6 months to 15 yea rs, regardless of their previous immunization status, and was effective in terminating this measles outbreak and in preventing morbidity, loss of live lihood and death despite the involvement of large numbers of adults in meas les transmission. The last measles case occurred within 3 weeks of completi ng ORI. The ORI campaign, which would have cost approximately US$ 3000 in 1 998, saved as many as 1155 person-days of work among 77 adults, prevented a n estimated 87 cases of diarrhoea and 46 cases of pneumonia, and averted 5 deaths.