Parasites resistant to the frontline malaria drug have spread westward from southeast Asia to just short of the Indian border -- a gateway to Africa, researchers warned Friday.
A spread into India "would pose a serious threat to the global control and eradication of malaria," said a statement that accompanied the study published in The Lancet Infectious Diseases.
"If drug resistance spreads from Asia to the African sub-continent, or emerges in Africa independently as we've seen several times before, millions of lives will be at risk."
Since the Plasmodium parasite developed resistance to other drug types, artemisinin is the best and safest medicine to treat the estimated 198 million malaria infections that occurred worldwide in 2013.
There were about 584,000 deaths, according to the UN's World Health Organization (WHO) -- 90 percent of them in Africa.
Artemisinin resistance has not yet been detected in Africa, but is a growing problem in southeast Asian nations like Cambodia, Thailand and Vietnam, and is suspected, though not proven, to have taken hold in South America.
Myanmar, which carries the region's highest malaria burden, is considered the parasite's main route from southeast Asia to India and beyond.