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Measles outbreak investigation in Ginnir district of Bale zone, Oromia region, Southeast Ethiopia, May 2019.

Research paper by Falaho Sani FS Kalil, Desta Hiko DH Gemeda, Mohammed Hasen MH Bedaso, Shukri Kabeta SK Wario

Indexed on: 12 Aug '20Published on: 11 Aug '20Published in: The Pan African medical journal



Abstract

Measles is a vaccine-preventable viral infection of humans, primarily affecting children <5 years. During early 2019, outbreak of measles occurred in Ginnir district of Bale zone, Southeast Ethiopia. We investigated to describe the outbreak and identify risk factors. We conducted a descriptive and 1:2 unmatched case-control study in Ginnir district from March 18 to April 29, 2019. Fifty-six cases and 112 controls were recruited. For descriptive study, we identified 1043 cases recorded on the line-list and for case-control study, cases were identified using national standard case-definition. Mothers of case-patients and controls were interviewed using structured questionnaire. We estimated vaccine efficacy (VE) from case-control study. We conducted bivariate and multivariable logistic regression. In four-months period, a total of 1,043 suspected measles cases epidemiologically linked to five laboratory confirmed cases reported. Of which, 555 (53.2%) were males and 714 (68.5%) were <5 years. The median age of cases was 36 months (IQR=12-60 months). The overall attack rate (AR) was 63/10,000 population with case fatality ratio of 0.5% (5 deaths/1043). Infant <9 months were the most affected age groups (AR=31/1000). Majority (79%) of measles cases were not vaccinated against measles. Last-year (2017/18) administrative measle vaccine coverage of the district was 76.7%. Being unvaccinated against measles (AOR=5.4, 95%CI=2.2-13.4), travel history (AOR=4.02, 95%CI=1.2-13.6), contact with measles case-patient (AOR=5.6, 95%CI=2.12-14.4) and mothers knowledge of measles transmission (AOR=0.36, 95%CI=0.15-0.87) were associated with measles infection. VE in children aged 9-59 months was 90% (95%CI=69-97%). This confirmed measles outbreak was caused by failure to vaccinate, as indicated by the high VE, low administrative coverage, and 79% unvaccinated cases. Strengthening routine and supplementary immunization are required. © Falaho Sani Kalil et al.