Effect of seasonal variability on the increased malaria positivity rate in drought-prone malaria endemic areas of Ethiopia

Malaria is a climate-sensitive and season-dependent disease that mainly affects the populations of tropical and subtropical regions of the world. Climatic variables such as rainfall, temperature, and humidity are identified as the driving factors affecting the epidemiology of malaria. In Ethiopia, recently unexpectedly high malaria burden accompanied by substantial morbidity and mortality is observed. The incidence rate of vector-borne diseases such as malaria is largely influenced by fluctuation of seasonal variables due to the proceeding global warming. Therefore, the study aimed to assess the impact of seasonal and climate variability on the burden of malaria in one of drought-prone areas of north central Ethiopia. The study was conducted in the Oromia zone of the Amhara regional state in Ethiopia. Data from patients tested and diagnosed with malaria between 2014 and 2019 were extracted from the medical records of the patients registered in all health facilities found in the zone. Additionally, meteorological data such as rainfall and temperature (maximum and minimum) were collected from the regional meteorological agency. Data were analyzed using R software. The malaria positivity rate recorded in this study was 12.7% (64,522/508,057). Months from June to December were significantly (p < 0.05) associated with high malaria positivity. Rainfall had a significant negative effect on malaria positivity (p = 0.042). Also, three to four months of lagged rainfall is associated with high malaria positivity (p < 0.05). However, monthly minimum temperature positivity influenced the rate of malaria positivity (exp = 0.037, p = 0.0098). While monthly mean maximum temperature showed a negative association with malaria positivity, although it was insignificant. In addition, malaria positivity significantly decreased from 2014 to 2019 by 20.5% (exp = 0.205, p < 0.0001). The seasonal and climatic variables evaluated in this study substantially affected the malaria positivity rate. Monthly mean temperature was the leading and predictor variable for malaria infection. Despite vigorous efforts by health authorities in the country at this level, following the neglected implementation of interventional activities in the nation for a couple of years, malaria-associated burdens have increased. As seasonal and climate variables could play a key role in the rising burden, concerned national or local health authorities, and policymakers should prioritize urgent interventional activities to control malaria in one of the drought-prone areas of Ethiopia.