The study, a mixed retrospective-prospective observational investigation published in BMC Infectious Diseases, enrolled laboratory-confirmed malaria cases among adults presenting to the emergency departments of the two hospitals between October 1 and December 31, 2025. The researchers applied the 2014 World Health Organization criteria for severe malaria, a standardized set of clinical and laboratory thresholds that includes coma, severe anaemia, renal impairment, respiratory distress, and other life-threatening features. By combining retrospective chart review with prospective observation, the team captured a realistic cross-section of how malaria actually presents in emergency settings in Central Ethiopia, rather than relying solely on curated inpatient populations.

The species distribution among the 318 laboratory-confirmed cases was striking. Plasmodium vivax accounted for 49.7 percent of infections, making it the single most prevalent species. Plasmodium falciparum followed at 38.4 percent, while mixed infections of both parasites made up the remaining 11.9 percent. This near-majority share for P. vivax marks a significant shift from the historical pattern in Ethiopia and much of Africa, where falciparum has traditionally dominated case counts and where vivax malaria was once considered a minor contributor to the regional burden.

Even more consequential is what the researchers found when they assessed disease severity. Severe malaria, as defined by WHO criteria, was diagnosed in 65.7 percent of all confirmed cases—an extraordinarily high proportion for an emergency department cohort. Severe anaemia, defined as a haemoglobin concentration below 5 grams per decilitre, was the most common severity criterion, present in 33.3 percent of patients. Anaemia at this level represents a medical emergency in its own right, depriving tissues of oxygen and placing particular strain on the heart, and it frequently necessitates blood transfusion alongside antiparasitic therapy.

When the analysis turned to the question of whether species mattered for severity, the answer was sobering. Severe malaria occurred in 65.2 percent of patients infected with P. vivax and 67.2 percent of those infected with P. falciparum—figures that are statistically indistinguishable. Using bivariate logistic regression, the investigators found no statistically significant association between malaria species and the likelihood of severe disease. In practical terms, the parasite that causes the majority of severe cases in a region cannot simply be assumed to be falciparum, and clinicians who triage vivax infections as inherently benign may dangerously underestimate the risk facing their patients.

The clinical outcomes documented in the study underscore the stakes. Most patients, 62.3 percent, were discharged directly from the emergency department after treatment, while 27.7 percent required admission to medical wards for ongoing care. In-hospital mortality stood at 4.4 percent—a figure that, while lower than mortality rates historically reported for severe falciparum malaria in intensive care settings, represents a substantial toll of deaths attributable to a disease in which both species contributed nearly equally to severe presentations. The high discharge rate also raises questions about the adequacy of follow-up, particularly for patients with vivax infections who require additional therapy beyond the acute episode.

That additional therapy is a cornerstone of the study’s conclusions. Unlike P. falciparum, which exists in the human body only as blood-stage parasites, P. vivax harbors a latent liver stage known as the hypnozoite. These dormant forms can reactivate weeks or months after the initial infection, causing relapses without any new mosquito bite. Eliminating the hypnozoites requires so-called radical cure, typically with the drug primaquine, which demands careful screening for glucose-6-phosphate dehydrogenase deficiency because the medication can trigger severe haemolysis in susceptible individuals. The authors emphasize that appropriate radical cure for P. vivax remains essential for malaria control and elimination efforts, precisely because untreated relapses sustain transmission and add cumulative burden of anaemia and illness.

The findings arrive at a pivotal moment for Ethiopia’s malaria programme. The country has pursued ambitious elimination targets, and declining overall transmission can paradoxically reshape the epidemiology of the disease, reducing acquired immunity in the population and allowing species that were previously overshadowed to emerge in greater numbers. A species shift toward vivax carries specific programmatic implications: diagnostic platforms must reliably distinguish the two species, since treatment algorithms differ; health systems must secure access to radical cure with appropriate G6PD screening; and surveillance frameworks designed around falciparum metrics may need recalibration to capture the true vivax burden.

The authors of the study argue that strengthening early diagnosis, prompt treatment, and species-specific case management is essential if Ethiopia is to maintain momentum toward malaria control and elimination. The near-parity in severe disease between the two species suggests that the clinical distinction between ‘benign’ and ‘malignant’ malaria, entrenched in textbooks and training curricula, may be misleading in settings like Central Ethiopia. Emergency clinicians managing febrile adults in the region should treat any confirmed malaria infection as potentially severe, regardless of the identified species, and should maintain a low threshold for transfusion in patients with profound anaemia.

The research also carries implications for the global malaria agenda. As endemic countries approach elimination, P. vivax is increasingly recognized as the parasite most likely to stand between them and their goal, owing to its relapsing biology and its ability to sustain transmission at low parasite densities that evade routine diagnostics. Evidence from Central Ethiopia that vivax now predominates in emergency presentations—and contributes to severe disease at rates equivalent to falciparum—adds clinical urgency to that strategic concern. Investment in tools such as highly sensitive rapid diagnostic tests, G6PD point-of-care testing, and tafenoquine, a single-dose radical cure agent, would directly address the gaps this study exposes. For the patients arriving at emergency departments in Hosanna and Werabe, the message is simpler: the malaria parasite in their blood, whatever its species, can make them critically ill, and the health system must be prepared to recognize and respond to that reality.

Subject of Research: The emerging predominance of Plasmodium vivax and its contribution to severe malaria among adults in Central Ethiopia.

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

Article References: Emerging predominance of Plasmodium vivax and its contribution to severe malaria in Central Ethiopia: a mixed retrospective-prospective study from two tertiary hospitals. (n.d.). https://doi.org/10.1186/s12879-026-14383-3

Image Credits: AI Generated

DOI: 10.1186/s12879-026-14383-3

Keywords: malaria, Plasmodium vivax, Plasmodium falciparum, severe malaria, severe anaemia, species shift, Ethiopia, emergency department, radical cure, malaria elimination, tropical medicine, BMC Infectious Diseases