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

Abstract

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 measles 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 was 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% developed 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 community vulnerable to the severe and extensive impact of measles virus importation. The ORI campaign targeted non-measles case children aged 6 months to 15 years, regardless of their previous immunization status, and was effective in terminating this measles outbreak and in preventing morbidity, loss of livelihood and death despite the involvement of large numbers of adults in measles transmission. The last measles case occurred within 3 weeks of completing ORI. The ORI campaign, which would have cost approximately US$ 3000 in 1998, saved as many as 1155 person-days of work among 77 adults, prevented an estimated 87 cases of diarrhoea and 46 cases of pneumonia, and averted 5 deaths.

PIP: A community survey of the epidemiology and impact of measles outbreak response immunization (ORI) in Espindola, Peru. Blood specimens from 29 clinical cases having the onset of symptoms within 5 weeks to collection were tested for the anti-measles virus nucleoprotein antibody. Questionnaires were given to the head of the household and the 29 clinical cases to identify clinical symptoms an disease outcomes and to determine vaccination coverage. Attack rates, vaccine effectiveness, and predictive value positive was also calculated. Findings showed that primary cases were frequent among adults, who accounted for 44% of cases. The attack rate among all susceptible people was 45.5% and was highest among adults aged 16-20 (61.2%). For the serologically confirmed cases, 60.7% developed diarrhea and 32.1% pneumonia. Case fatality rate was 19.1% for children aged 0-23 months and 1.5% for adults aged 16-40 years. The lack of national campaigns or access to routine immunization caused the severe impact of measles virus outbreak. The ORI campaign targeted nonmeasles case children aged 6 months to 15 years regardless of immunization status, which was effective in terminating measles outbreak, morbidity, and mortality. This campaign cost approximately US$3000 and in 1998 saved 1155 person-days of work among 77 adults. It also prevented 87 diarrhea and 46 pneumonia cases and averted 5 deaths.