Background: Outbreak investigation is the diagnosis and confirmation of suspected measles outbreak by using appropriate procedures to take a suitable measure toward controlling the outbreak.  Although Ethiopia is working towards measles elimination, recurrent measles outbreak is occurred. To take appropriate measures, previously, many fragment and inconsistent outbreak investigations were done, but there is no consolidated evidence on measles outbreak investigation. This review aimed to identify cumulative evidence on measles outbreak investigation.

Methods: A systematic literature review and Meta-analysis was used. We searched Google Scholar, MEDLINE/PubMed, Cochrane/Wiley Library, EMBASE, Science Direct, and African Journals Online databases by using different terms. Investigations that applied any study design, data collection and analysis methods related to measles outbreak investigation were included. Data were extracted in excel spread sheet and entered into Review manager (RevMan) version 5.4 and comprehensive meta-analysis (CMA) version 4.0 software for meta-analysis. The I² statistics was used to test heterogeneity and Begg’s and Egger’s tests were used to assess publication bias. Odds ratio (OR) with 95% confidence interval (CI) was presented using forest plots.

Results: Eight measles outbreak investigations with 3004 measles cases and 33 deaths were included in this study. The pooled attack rate (AR) and case fatality rate were 34.51/10,000 [95% CI; 21.33-47.70/10,000] population and 1.16% [95% CI; 0.24%-2.08%] respectively. Subgroup analysis revealed that the highest attack rate of measles outbreak in Oromia region (63.05/10,000 population) and the lowest in Amhara region (17.77/10,000 population). Associated factors with measles outbreak: being unvaccinated, OR=5.96 (95% CI: 3.28-10.82), contact history, OR=3.90(95% CI: 2.47-6.15) and travel history, OR= 3.03 (95% CI: 1.81-5.09).

Conclusion: We identified that there is significant evidence on description of outbreaks. Higher attack rate and case fatality rate was observed. Being unvaccinated, contact and travel history were factors associated with measles outbreak. Routine vaccination and contact tracing should be strengthened.

Keywords: Measles, Outbreak, Investigation, Review, Ethiopia