Severe vivax malaria: how parasite genomics and G6PD testing are rewriting the radical cure playbook

For decades, Plasmodium vivax was dismissed as the benign sibling of the malaria family, a parasite that made people ill but rarely killed them. That comfortable assumption has now collapsed. A growing body of clinical and molecular evidence confirms that P. vivax can drive severe, life-threatening disease, including cerebral malaria, profound anemia, acute respiratory distress syndrome, liver dysfunction, and acute kidney injury. An editorial published in Frontiers in Malaria by Dhanpat Kumar Kochar of Sardar Patel Medical College in Bikaner, India, synthesizes a new Research Topic on global perspectives on severe vivax malaria, arguing that effective control of the parasite demands a deep understanding of both the biological factors that fuel severe disease and the practical challenges of treating it safely.

The shift in perception is more than academic. As malaria elimination programs push into regions where P. vivax dominates, the parasite’s ability to relapse and its capacity to cause severe complications threaten to undermine hard-won gains. The articles gathered in this Research Topic highlight the complex interplay among parasite biology, host genetics, and treatment approaches, emphasizing that managing vivax malaria goes far beyond simply clearing the parasite from the bloodstream. It requires accounting for host genetic factors that determine whether a treatment will be safe and effective for a given patient.

One of the thorniest problems in vivax malaria control is achieving a safe and effective radical cure. Primaquine, currently the only widely available 8-aminoquinoline drug, is the sole licensed agent capable of eliminating dormant liver-stage hypnozoites, the forms of the parasite that lie in wait and trigger relapses weeks or months after an initial infection. But primaquine’s use is complicated by host genetic factors, most notably glucose-6-phosphate dehydrogenase (G6PD) deficiency and variations in drug metabolism. G6PD is an enzyme that protects red blood cells from oxidative damage, and individuals with deficient variants can suffer acute hemolysis when exposed to oxidative stress from the drug.

A clinical trial included in the Research Topic assessed low-dose primaquine given alongside artemether-lumefantrine or dihydroartemisinin-piperaquine in the Solomon Islands. While both combinations reduced recurrent parasitemia compared to treatments without primaquine, neither achieved optimal radical cure efficacy. These results suggest that currently recommended lower-dose regimens may not be sufficient in areas where relapsing parasite strains are common, and they underscore the need for optimized dosing strategies that balance effectiveness against safety. Poor adherence to the conventional 14-day primaquine regimen further compounds the problem, contributing to treatment failure and recurrent infections, while regional variations in parasite responses to antimalarial therapies reflect differences in parasite genetic diversity, drug susceptibility, and transmission intensity.

In this context, tafenoquine warrants parallel consideration alongside primaquine as an alternative short-course anti-relapse therapy. Its single-dose regimen may help overcome the adherence barriers associated with prolonged primaquine treatment. However, tafenoquine is not a universal replacement for primaquine. It carries important limitations, including the absolute requirement for reliable quantitative G6PD testing before administration, contraindications or restricted use in individuals with significant G6PD deficiency, and the need for careful patient selection and safety monitoring. The choice of radical cure, the editorial argues, should therefore be individualized according to the patient’s G6PD status, regional parasite characteristics, local drug availability, and the realistic likelihood of adherence.

The significance of these safety concerns is brought into sharp relief by a case report of primaquine-induced hemoglobinuria in a G6PD-deficient patient with the Mahidol variant from Bangladesh. The case demonstrates the potentially severe outcomes of administering primaquine without prior G6PD screening, resulting in acute severe hemolysis that required blood transfusion. The report emphasizes the practical value of point-of-care G6PD testing and genetic screening in malaria-endemic areas. As global malaria programs improve access to radical cure, incorporating reliable G6PD diagnostics into everyday clinical practice will be crucial in minimizing adverse outcomes while ensuring effective relapse prevention.

Beyond treatment challenges, understanding the biological basis of severe vivax malaria remains essential. A genomic study by Tahbildar and colleagues offers new insights into parasite factors that may be linked to disease severity. Using a high-resolution comparative genomic hybridization platform, the researchers identified extensive copy number variations (CNVs) across all 14 chromosomes of P. vivax isolates obtained from cerebral malaria cases, in comparison to uncomplicated infections. These genomic changes affected genes involved in erythrocyte invasion, immune evasion, cytoadherence, and antimalarial drug resistance, suggesting that structural genomic variation might play a role in parasite adaptation and virulence.

Notably, the study detected amplifications in multidrug resistance-associated genes, reticulocyte-binding proteins, merozoite surface proteins, and virulence-associated vir gene families, pointing to potential mechanisms that may enhance parasite adaptability and pathogenicity. Importantly, the analysis also revealed CNVs within intergenic regions, raising the possibility that regulatory genomic elements contribute to parasite fitness and disease outcomes. Although the limited sample size precludes definitive causal inferences, these findings represent a pioneering effort to characterize structural genomic variation in severe P. vivax malaria and provide a valuable basis for identifying biomarkers of severe disease and understanding the evolutionary factors underlying parasite pathogenicity.

Taken together, the studies in this Research Topic reinforce several key points. Severe vivax malaria is a real clinical condition shaped by multiple factors affecting both host and parasite biology. Managing the disease effectively requires considering host genetic factors that influence treatment safety and effectiveness, not just parasite clearance. And advancements in molecular epidemiology and genomics are deepening our understanding of parasite diversity, potentially enabling better diagnostic, prognostic, and therapeutic tools. The combination of clinical medicine, pharmacogenomics, and parasite genomics showcased here reflects the multidisciplinary approach needed to tackle the evolving challenges presented by P. vivax.

As malaria elimination efforts progress, the ongoing issues of relapsing infections, emerging drug resistance, and severe clinical forms could threaten control gains. Future research, the editorial concludes, should focus on integrating genomic surveillance, enhancing point-of-care diagnostics, personalizing radical cure approaches, and conducting long-term clinical studies to better identify the factors that contribute to severe disease and treatment outcomes. These priorities are vital for creating safer and more effective strategies for malaria control and elimination worldwide.

Subject of Research: Severe vivax malaria

Article Title: Editorial: Global perspectives on severe vivax malaria: incidence, outcomes, and biological mechanisms

Article References: Kochar, D. K. (2026). Editorial: Global perspectives on severe vivax malaria: incidence, outcomes, and biological mechanisms. Frontiers in Malaria, 4, Article 1923808. https://doi.org/10.3389/fmala.2026.1923808

Image Credits: AI Generated

DOI: 10.3389/fmala.2026.1923808

Keywords: Plasmodium vivax, severe malaria, cerebral malaria, primaquine, tafenoquine, G6PD deficiency, radical cure, hypnozoites, copy number variation, parasite genomics, malaria elimination, antimalarial drug resistance