Emerging predominance of Plasmodium vivax and its contribution to severe malaria in Central Ethiopia: a mixed retrospective-prospective study from two tertiary hospitals

Abstract Background Malaria remains a major public health challenge in Ethiopia. While Plasmodium falciparum has historically been associated with severe disease, the clinical importance of Plasmodium vivax is increasingly recognized. Objective This study aimed to determine the prevalence, species distribution, severity, associated factors, and clinical outcomes of malaria among adults attending emergency departments in Central Ethiopia. Methods A mixed retrospective-prospective observational study was conducted in the adult emergency departments of two tertiary hospitals from October 1 to December 31, 2025. Severe malaria was defined according to the 2014 World Health Organization (WHO) criteria. The association between malaria species and severe malaria was examined using bivariate logistic regression. Results Among 318 laboratory-confirmed malaria cases, P. vivax was the predominant species (49.7%), followed by P. falciparum (38.4%) and mixed infections (11.9%). Severe malaria was diagnosed in 65.7% of patients, with severe anaemia (haemoglobin < 5 g/dL) being the most common severity criterion (33.3%). Severe malaria occurred in 65.2% of patients with P. vivax and 67.2% with P. falciparum. No statistically significant association was found between malaria species and severe malaria. Most patients (62.3%) were discharged from the emergency department, while 27.7% were admitted to medical wards. In-hospital mortality was 4.4%. Conclusion P. vivax was the predominant malaria species among adults presenting to the two tertiary hospitals, and both P. vivax and P. falciparum were associated with substantial severe disease. Severe anaemia was the most common manifestation. Strengthening early diagnosis, prompt treatment, species-specific case management, and appropriate radical cure for P. vivax remains important for malaria control and elimination efforts. Clinical trial statement This manuscript does not describe a clinical trial.