infecting a red blood cell
Image courtesy of St. Jude
Children’s Research Hospital
The first global mapping of artemisinin resistance indicates that resistance to the drug, which is used to treat Plasmodium falciparum malaria, is confined to Southeast Asia and has not yet spread to sub-Saharan Africa.
Results of the effort, known as the KARMA study, were published in NEJM.
The study builds on the 2014 discovery that the K13 gene is the major determinant of P falciparum’s resistance to artemisinin.
Researchers studied the diversity of the K13 gene in 14,037 blood samples taken from P falciparum-infected patients in 59 malaria-endemic countries—72% in Africa, 19% in Asia, 8% in Latin America, and 1% in Oceania. All samples were collected after 2012.
The researchers identified 108 nonsynonymous K13 mutations. In Asia, 36.5% of the mutations were distributed within 2 areas—Cambodia-Vietnam-Laos and western Thailand-Myanmar-China—with no overlap.
In samples from Africa, the researchers identified nonsynonymous K13 mutations that were not associated with artemisinin resistance, including the most frequent mutation found in Africa, A578S.
“We suspect that only a small number of mutations appear to be associated with resistance, which should facilitate global monitoring of resistance to artemisinin,” said study author Odile Mercereau-Puijalon, PhD, of the Institut Pasteur in Paris, France.
“Until now, scientists have not had the tools to be properly informed about the nature of resistance to antimalarial drugs in key affected regions such as sub-Saharan Africa,” added Didier Ménard, PhD, of the Institut Pasteur in Phnom Penh, Cambodia.
“We now have the capacity, thanks to molecular markers, to be able to trace—at a global level and virtually in real-time—resistance to antimalarial drugs. We must ensure that we use this technology to keep us a step ahead of the parasite.”
