Image courtesy of
CDC/Mae Melvin
A lineage of multidrug-resistant malaria parasite has spread widely and is now established in parts of Thailand, Laos, and Cambodia, according to a study published in The Lancet Infectious Diseases.
The
researchers said their findings suggest an artemisinin-resistant
Plasmodium falciparum lineage probably arose in western Cambodia and
then spread to Thailand and Laos, outcompeting other parasites and
acquiring resistance to piperaquine.
“We now see this very successful, resistant parasite lineage emerging, outcompeting its peers, and spreading over a wide area,” said study author Arjen Dondorp, MD, of Mahidol University in Bangkok, Thailand, and the University of Oxford in Oxford, UK.
“It has also picked up resistance to the partner drug piperaquine, causing high failure rates of the widely used artemisinin combination therapy, DHA-piperaquine. We hope this evidence will be used to re-emphasize the urgency of malaria elimination in the Asia region before falciparum malaria becomes close to untreatable.”
For this study, Dr Dondorp and his colleagues examined blood spot samples from patients with uncomplicated, P falciparum malaria collected at sites in Cambodia, Laos, Thailand, and Myanmar.
The researchers found evidence to suggest that PfKelch13 C580Y, a single mutant parasite lineage, has spread across Cambodia, Laos, and Thailand, replacing parasites containing other, less resistant mutations.
Although the C580Y mutation does not confer a higher level of artemisinin resistance than many other PfKelch13 mutations, it appears to be fitter, more transmissible, and spreading more widely.
“It isn’t that the C580Y mutation itself makes the malaria parasites fitter, it is the other genetic changes that go along with it—hence, the critical emphasis on the term ‘lineage,’” said Nicholas White, also of Mahidol University and the University of Oxford.
“This is what makes superbugs—the evolution of multiple factors that make them fitter and more transmissible. The spread and emergence of drug-resistant malaria parasites across Asia into Africa has occurred before. Last time, it killed millions. We need to work with our policy, research, and funding partners to respond to this threat in Asia urgently to avoid history repeating itself.”
In particular, the researchers are calling for accelerated efforts in the Greater Mekong subregion and closer collaboration to monitor any further spread in neighboring regions.
“We are losing a dangerous race to eliminate artemisinin-resistant falciparum malaria before widespread resistance to the partner antimalarials makes that impossible,” White said. “The consequences of resistance spreading further into India and Africa could be grave if drug resistance is not tackled from a global public health emergency perspective.”
