Background: Africa accounts for 94% of malaria-related morbidity and mortality. Ethiopia is one of ten African nations that share this burden, with 60% of the population living in malaria-risk areas. Nationally, the west Arsi zone's Nensebo district is stratified as having very low transmission. However, Melka Denbi kebele reported an unfamiliar high number of malaria cases to this district during the 21st WHO week of 2021. This study aimed to investigate the magnitude and associated factors with the malaria outbreak.
Methods: A descriptive study followed by an unmatched case-control study was conducted among 86 cases and 172 controls. Cases were those confirmed positive by a rapid diagnostic test (RDT) and controls were the neighborhood of cases confirmed negative by RDT. Logistic regression was computed to identify malaria contracting factors at a p-value <0.05, CI 95%.
Result: Plasmodium vivax (PV) 105(52.8%) was the predominant species. Stagnant water/intermittent river within 1 km of the vicinity (AOR=4.28; 95%CI: 1.8-10.27) and staying out at night (AOR=3.94; 95%CI: 2.18-7.37) were risk factors. Screened houses (AOR=0.49; 95%CI: 0.27-0.89), good 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) were protective.
Conclusion and recommendation: Illness was predominantly due to PV species known for their relapsing features. Stagnant water near homes and staying outdoors at night were risk factors. Screening houses and a good awareness of malaria reduce the risk of contracting it. Regular environmental monitoring, ensuring radical cure, and further study with a detailed entomological survey were our recommendations.