Scientists, yesterday, confirmed that malaria parasites in Africa had developed resistance to World Health Organisation (WHO)-approved drug-of-choice/frontline medication, Artemisinin Combination Therapies (ACTs).
The ‘gold standard’ treatment for the ailment, the drug family, including artemisinin and its derivatives, are often administered alongside ‘partner’ medicines in what are called ACTs, because multiple drugs are more difficult for parasites to develop resistance against.
But, a new study, published in the New England Journal of Medicine, showed observable drop in ACTs’ ability to quickly treat people with the disease.
Signs of drug resistance have long been present on the continent. For instance, in Rwanda between 2012 and 2015, scientists detected existence of gene mutations associated with resistance in malaria parasites.
The first signs of resistance to artemisinin and its relatives appeared in Cambodia in the early 2000s. Within a few years, malaria parasites in Southeast Asia began to evade some of the partner drugs in the ACTs, rendering some of the most effective drug cocktails against malaria useless in the region and forcing public health officials to scramble for efficacious combinations.
A biochemist at the University of Melbourne in Australia and researcher of the molecular basis of antimalarial resistance, Prof. Leann Tilley, said: “We’ve all been expecting and dreading this for quite some time.”
She expressed concern over the new development in Africa, describing it as dire. More than 90 per cent of malaria cases and deaths worldwide occur on the continent.
Also discomforting, is the finding that the resistance in Africa arose independently of the resistant parasite strains in Southeast Asia, meaning the prevailing strains in Africa might continue evolving to culminate in a ‘super resistant’ parasite that becomes dominant.
Head of malaria research at Mahidol Oxford Tropical Medicine Research Unit in Bangkok, Arjen Dondorp, submitted: “It is certainly a disturbing finding, because we rely completely on these artemisinin-combination therapies.”
Scientists fear that a similar scenario in Southeast Asia would unfold in Africa – and in light of the lack of access to adequate healthcare in many parts of Sub-Saharan Africa, it could exact a huge toll.
In the study, conducted in Uganda from 2017 to 2019, researchers treated 240 people, who had malaria, by giving them intravenous artesunate, a potent derivative of artemisinin, three times over the course of a day, followed by a standard three-day course of ACT pills. Doctors typically administer artemisinins without partner drugs to people only when they have severe malaria.
The team found that, for 14 participants, it took longer than five hours to clear half of the malaria-causing parasites (Plasmodium falciparum), which meets the World Health Organisation (WHO) definition for resistance. (People with malaria usually clear half the parasites within a couple hours of treatment with artesunate.) Parasites in 13 of these participants had one of two concerning mutations in their kelch13 gene, which has been linked with antimalarial resistance in Southeast Asia.
A parasitologist at Juntendo University in Tokyo and co-author of the study, Toshihiro Mita, noted: “We didn’t know if these parasites were actually resistant to drugs in humans.”
An infectious disease clinician at the University of California, San Francisco, United States, who works with the WHO to study malaria in Uganda, Philip Rosenthal, said for now, there appears to be a few clinical consequences of the artemisinin resistance. The parasites take longer to clear in some severe cases, and they might return within a week or so, but the ACT of choice in much of sub-Saharan Africa — a combination of artemether, another derivative of artemisinin, and a partner drug called lumefantrine – seems to still be effective.
Pascal Ringwald, who leads the WHO Global Malaria Programme’s Drug Resistance and Containment Unit, said although the global agency has mounted an aggressive campaign to eliminate resistant parasites in Southeast Asia by rapidly deploying ACTs on sick individuals, he added that the same approach “is unrealistic in sub-Saharan Africa given how widespread the disease is there.”