Background: Dengue fever is a mosquito-borne viral infection caused by the dengue virus and is endemic to most tropical and subtropical parts of the globe. In Ethiopia, dengue fever initially appeared in 2013 and became a major public health problem. The objective of this study was to examine an outbreak of dengue fever in Mille Woreda, Zone One, Afar Region, Ethiopia, by reporting its time, place, and person distribution, and identifying the risk factors involved.

Methods: We carried out a descriptive study followed by a case-control study with a ratio of 1:2. We employed the case definition of the World Health Organization to make cases in Mille Woreda from April 13 to May 7, 2023. Controls were included from the same town who were not showing symptoms of dengue fever. Serum samples were subjected to reverse transcription polymerase chain reaction (RT-PCR) for detection of the dengue virus and determination of serotypes. A standard questionnaire was used to collect socio-demographic, behavioural, and environmental characteristics. Multivariate logistic regression was used for analysis.

Results: We identified 57 cases and 114 controls. The overall attack rate was 367/10,000. Eight out of ten of the serum samples were positive for dengue virus serotype DEN-3. In multivariate analysis, never having heard of dengue fever (Adjusted odds ratio [AOR]: 3.76, 95% CI: 1.46–9.65), not knowing how it's transmitted (AOR: 2.88, 95% CI: 1.14–7.25), and long-lasting insecticidal net use (AOR: 6.83, 95% CI: 2.63–17.7) were statistical risk factors. Wearing long sleeves (AOR: 0.11, 95% CI: 0.04–0.28), on the other hand, was a protective behavior.

Conclusion: It was confirmed that dengue fever outbreak occurred in Mille Woreda. Data from this study offer evidence-based data on modifiable risk factors that have led to the outbreak. Public health education, intensified vector control intervention, and strengthened dengue surveillance systems are advised to avert future outbreaks.