Resistance to artemisinin-based malaria medications seems to be spreading beyond western Cambodia, where it was first detected, U.S. global malaria coordinator Timothy Ziemer said during a visit to the region this week for a conference, Agence France-Presse reports.

First spotted in western Cambodia in 2007, there are now signs of artemisinin-resistance noted in southern Myanmar and potentially emerging resistance along the Chinese-Myanmar border and in southern Vietnam near Cambodia, according to Ziemer.

Still, the total number of malaria cases had fallen, Ziemer told the conference. “In Vietnam, for example, they were down from about 190,000 in 1991 to 15,000 by 2008, he said. ‘But it is essential that national governments remain focused to contain and eventually eliminate these multi-drug resistant strains,’ he told the conference on international cooperation against infectious diseases,” AFP writes. Ziemer noted the importance of getting rid of counterfeit and substandard drugs, which increase resistance.

The WHO “warned early last year that parasites resistant to the drug artemisinin had emerged along the border between Cambodia and Thailand,” according to the news service (6/18).