The emergence of new drug resistant malaria at the Thai-Cambodian border could "seriously undermine" efforts to bring the disease under control, the World Health Organization said Wednesday.
"Surveillance systems and research studies... are providing new evidence that parasites resistant to artemisinin have emerged along the border between Cambodia and Thailand where workers walk for miles every day to clear forests," said the WHO in a statement.
"The risk that they may be infected with a drug-resistant form of malaria could set back recent successes to control the disease," it said.
New artemisinin-based medication has been largely credited in recent years for increasing recovery rates from the mosquito-transmitted disease that kills one million people a year.
It was regarded as a replacement for older drugs that were fast becoming useless in several areas of the world as the malaria parasite developed resistance to them.
"If we do not put a stop to the drug-resistant malaria situation that has been documented in the Thai-Cambodian border, it could spread rapidly to neighbouring countries and threaten our efforts to control this deadly disease," said WHO Assistant Director-General Hiroki Nakatani.
The WHO said it had obtained a 22.5-million-dollar grant from the Gates Foundation to find ways of containing the resistant strains of malaria.
Strains of malaria resistant to drugs such as mefloquine and sulfadoxine-pyrimethamine also emerged several years ago at the Thai-Cambodian border.