Background: Malaria-related morbidity and mortality are 94% concentrated in Africa. Ethiopia is one of ten African countries affected by malaria, with 60% of the population living in malaria-risk areas. Recently, seasonal outbreaks have been reported in all regions, including previously malaria-free areas. Nationally, the Nensebo district of the west Arsi zone is classified as having very low transmission. During the 21st WHO week of 2021, Melka Denbi kebele reported an unusually high number of malaria cases to this district. The purpose of this study was to look into the magnitude of the malaria outbreak and the factors that contributed to it.
Methods: A descriptive study was followed by an unmatched case-control study on 86 cases and 172 controls who were chosen at random. Malaria cases were those who were confirmed positive by rapid diagnostic test (RDT) and were line-listed at a health facility, while controls were those who lived nearby and were confirmed negative by RDT. At a p-value of 0.05 and a 95% confidence interval, logistic regression was used to identify malaria contracting factors.
Results: With a mean age of 22 (12.31SD), the overall attack rate was 20.2/1000. Plasmodium vivax (PV) 105 (52.8%) was the most common. Staying out at night (AOR=3.94; 95%CI: 2.18-7.37) and stagnant water/intermittent river within 1 km of the vicinity were risk factors. Screened houses were protective (AOR=0.49; 95%CI: 0.27-0.89), as was knowledge of malaria transmission (AOR=0.51; 95%CI: 0.28-0.93) and prevention and control methods (AOR=0.50; 95%CI: 0.27-0.93).
Conclusion: The illness was caused primarily by PV species known for their relapsing characteristics. Risk factors included stagnant water near homes and sleeping outside at night. Malaria screening centers and increased public awareness reduce the risk of contracting the disease. Our recommendations included regular environmental monitoring, behavioral change communication, ensuring radical cure, and further research with a detailed entomological survey and climate variables.