Measles outbreak investigation in Zaka, Masvingo Province, Zimbabwe, 2010

BACKGROUND: A measles outbreak was detected at Ndanga Hospital in Zaka district Masvingo Province on the 5th of May 2010 and there were five deaths. Source of infection was not known and an investigation was carried out to determine factors associated with contracting measles in Zaka district. MATERIALS AND METHODS: A 1:1 unmatched case control study was conducted. A case was a person residing in Zaka district who developed signs and symptoms of measles or tested IgM positive from 06 May 2010 to 30 August 2010. A control was a person residing in the same community who did not have history of signs and symptoms of measles during the same period. A structured interviewer administered questionnaire (translated into shona) was used to solicit information from cases and controls. Ethical consideration like written consent from all participants, respect and confidentiality were observed. Permission to carry out the study was obtained from the medical research Council of Zimbabwe and the provincial Medical Directors Masvingo. Epi info was used to calculate frequencies, odds ratios and perform logistic regression to control for confounding variables. FINDINGS: A total of 110 cases and 110 controls were recruited. Most cases (63.03%) were from the apostolic sect while 44.7% of controls were from orthodox churches. Contact with a measles case [AOR= 41.14, 95% CI (7.47-226.5)],being unvaccinated against measles [AOR= 3.96, 95%CI (2.58-6.08)] and not receiving additional doses of measles vaccine [AOR 5.48, 95% CI (2.16-11.08)] were independent risk factor for contracting measles. Measles vaccination coverage for Zaka district was 75%. The median duration for seeking treatment after onset of illness was three days (Q1=2; Q3=7). There were no emergency preparedness plans in place. CONCLUSION: This outbreak occurred due to a large number of unvaccinated children and a boarding school that facilitated person to person transmission. We recommend mandatory vaccination for all children before enrolling into schools. As a result of the study one day training on outbreak management and surveillance was done with all District Nursing Officers and Environmental Health Officers in personnel in the province.