Measles is a highly contagious vaccine-preventable disease. In 2010 an estimated 140,000 deaths occurred worldwide. The aim of the investigation was to describe magnitude of measles outbreak and to identify its’ risk factors. Unmatched case-control study was conducted from October 1-20, 2018 in Hudet District. Sample size were determined based on similar studies. All 358 cases were line listed and we used simple random sampling to take 39 cases from the line list. On case-control study a total of 116 data (39 cases and 77 community controls) were collected using structured questionnaire. We used a WHO adopted standard case definition to identify cases. The outbreak was confirmed by conventional polymerase chain reaction (PCR). Bivariate and multivariate analysis was conducted using odds ratio with 95% confidence interval and P-value < 0.05 by using SPSS. A total of 358 cases with attack rate (AR) of 597/100,000 and 13 deaths with case fatality rate (CFR) of 4% were identified. Infants were more affected AR 1340, followed by 1-4 years AR 1000 cases per 100,000 population. Furthermore, 13(3.7%) of cases were 0-6 months and 19(5.33%) of cases were 6-12 months of age. The median age of the cases was 15 years (2 months to 57 years). 3 out of 5 samples were positive for measles IgM. Statistically significant variables on multi-variate analysis were family size above four (AOR: 21.8; 95% CI: 2.14-222.2; P: 0.009), travel history to measles affected area (AOR: 16.3; 95% CI: 2.1-125.7; P: 0.007), being malnourished (AOR: 11.24; 95% CI: 1.21-104.5; P: 0.033), being vaccinated (AOR: 0.11; 95% CI: 0.015-0.804; P: 0.03), knowing measles is vaccine preventable (AOR: 0.093; 95% CI: 0.011-0.82; P: 0.032). Mass vaccination campaign conducted. Malnutrition, low awareness level, inadequate and poor cold chain management and low vaccination coverage contributing to the outbreak. Undertaking supplementary immunization, enhancing routine vaccination coverage, increasing community awareness, strengthening cold chain management and managing malnourished cases can reduce measles outbreak.
Keywords: measles outbreak, Case control study, pastoralists, Somali, Ethiopia, 2018.