A strain of malaria resistant to two key anti-malarial medicines has become dominant in Vietnam, Laos and northern Thailand after spreading rapidly from Cambodia, scientists have warned.
Using genomic surveillance to track the spread of drug-resistant malaria, the scientists found that the strain, known as KEL1/PLA1, has also evolved and picked up new genetic mutations that may make it yet more resistant.
A similar resistance to a long-time front-line malaria drug, chloroquine, contributed to millions of deaths across Africa in the 1980s.
Malaria can be successfully treated with medicines if it is caught early enough, but resistance to anti-malarial drugs is growing in many parts of the world, especially in Southeast Asia.
The first-line treatment for malaria in many parts of Asia in the last decade has been a combination of dihydroartemisinin and piperaquine, also known as DHA-PPQ.
Researchers found in previous work that a strain of malaria had evolved and spread across Cambodia between 2007 and 2013.
The latest research, published in The Lancet Infectious Diseases journal, found it has crossed borders and tightened its grip.