Age-Related and Seasonal Variation in Malaria and Other Causes of Fever and Their Association With Clinical Outcomes in Southern Angola: A Hospital-Based Study.

backgroundAcute febrile illnesses in sub-Saharan Africa are often attributed to malaria, yet many patients test negative for malaria parasites. The aetiology of nonmalarial fevers remains understudied. Here, we examine likely causes of febrile illnesses and their association with poor clinical outcomes in Angola.

methodsIn September-October 2023 and May-June 2024 we enrolled 849 febrile patients with ages between 2 months and 94 years in two tertiary hospitals of Lubango city that serve 7 million people in southern Angola. We used clinical assessments and locally available laboratory diagnostics to assign likely causes of fever and applied logistic regression analysis to identify factors independently associated with an increased risk of hospital admission and death.

resultsOverall, 67.6% of the patients tested negative for malaria by microscopy, with upper (13.0%) and lower (19.5%) respiratory infections and gastrointestinal infections (16.7%) being leading causes of nonmalarial fever. The frequencies of gastrointestinal, upper respiratory, and genitourinary infections varied markedly with age, and malaria predominated at the beginning of the dry season. Malaria and lower respiratory infections were associated with increased risk of hospitalization (odds ratio [OR] = 3.20 and 5.17, p < 0.0001), while malaria and central nervous system infections were linked to significantly higher mortality (OR = 1.90 and 6.30, p < 0.0001). Empirical antibiotic use was widespread, even without clinical or laboratory evidence of bacterial infection.

conclusionMost fevers in southern Angola are of nonmalarial origin, underscoring the need for better diagnostic strategies to guide specific treatment and reduce unnecessary antibiotic use.