The parasite that causes the most deadly form of malaria is becoming more resistant to the most effective drug used to treat it, scientists in Southeast Asia are reporting.
“Since the turn of the century, we have been winning, and we think we’ve saved about three million lives,” said the senior author, Dr. Nick White, a professor of tropical medicine at Mahidol University in Thailand and Oxford University in England. But he added:
“This paper shows that resistance has spread across Southeast Asia, which is a much worse situation than we previously thought, and it’s really knocking on the doors of India.”
To track the spread of the problem, the researchers did a randomized trial to detect artemisinin resistance in 1,241 adults and children in 10 countries in Southeast Asia and Africa with the malaria parasite Plasmodium falciparum.
Two groups were given different doses of artesunate, an artemisinin derivative, for three days; then all received three days of combination therapy with artesunate and other drugs.
The proportion who still had microscope-detectable infection after 72 hours ranged from zero in Kenya to 68 percent in eastern Thailand.
“Right now, we have no evidence that this artemisinin resistance has spread to Africa,” Dr. White said. “But twice in the past, resistance has emerged at the border between Thailand and Cambodia and spread to and across Africa, killing millions of people. We now see the same story beginning to recur.”
New anti-malaria drugs are being developed, but they will not be ready for several years, and Dr. White does not seem reassured. “It’s taking the same path it did before,” he said.