Resistance to the main drug in frontline malaria treatments is becoming more widespread across East Africa, according to new research by Imperial College London.
The study, published in The Lancet Infectious Diseases, maps the rise in artemisinin resistance in the region and suggests one of the safeguards built into these treatments is being worn away.
The researchers warn that their findings raise the risk that the effectiveness of current treatments could decline over time if resistance continues to spread.
Artemisinin is the central drug in the combination treatments used against malaria across Africa. Studying the parasite that causes the disease (Plasmodium falciparum), researchers found a sharp rise in strains that are resistant to it — a warning that its power to clear infections may weaken over time.
Artemisinin resistance occurs when malaria parasites acquire mutations that blunt the drug's effect. Artemisinin is the fast-acting core of the combination therapies (ACTs) used as first-line malaria treatment worldwide.
Drawing on 185,099 samples from published studies across 47 African countries, the researchers produced the first high-resolution maps of how genetic markers of resistance have expanded across both time and geography in Africa.
They found that artemisinin partial resistance is now firmly established across most of Uganda and Rwanda and along the Ethiopia–Eritrea–Sudan border, and no longer confined to isolated pockets.
In Rwanda's Northern Province, predicted prevalence rose from under 1% in 2012 to 62% in 2024.
Researchers say the pattern mirrors the early warning signs that preceded widespread ACT failure in southeast Asia.
Dr Robert Verity of Imperial College London, who led the analysis, said: "Artemisinin-based drugs underpin malaria treatment across sub-Saharan Africa – and our findings are a warning that we can't take them for granted. We need new therapies and smarter ways to deploy existing ones before resistance outpaces us.
"We also need to strengthen molecular surveillance across sub-Saharan Africa, and in neighbouring countries where similar signals may emerge. Spotting these genetic markers early gives us a head start, providing time to respond well before they translate into treatment failure.
"Drug resistance is a major challenge and is undermining global efforts to control and eliminate the burden of malaria. As with other treatments, like antibiotics, artemisinin-based drugs are a victim of their own success, with their widespread use contributing to the rapid rise in drug resistance. Artemisinin-based drugs have been life-changing for millions of people across Sub-Saharan Africa – losing these treatments would be disastrous for public health."
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'Mapping the prevalence of molecular markers of Plasmodium falciparum artemisinin partial resistance in Africa: a systematic review and spatiotemporal modelling study' by Neeva Wernsman Young, Cécile P G Meier-Scherling, Gina Cuomo-Dannenburg et al. is published in Lancet Infectious Diseases. DOI: https://doi.org/S1473-3099(26)00237-9
