A lineage of multidrug resistant P. falciparum malaria superbugs has widely spread and is now established in parts of Thailand, Laos and Cambodia, a study has warned.

Noting that the further spread of these multidrug resistant parasites through India to sub-Saharan Africa would be a global public health disaster, the authors of the study called for accelerated efforts in the Greater Mekong Sub-region and closer collaboration to monitor any further spread in neighbouring regions.

The malaria superbug lineage is causing high treatment failure rates for the main falciparum malaria medicines, artemisinin combination therapies (ACTs), according to the study published today in the journal The Lancet Infectious Diseases.

The emergence and spread of artemisinin drug resistant P falciparum lineage represents a serious threat to global malaria control and eradication efforts.

"We now see this very successful resistant parasite lineage emerging, outcompeting its peers, and spreading over a wide area," said study lead author Arjen Dondorp from Mahidol Oxford Tropical Medicine Research Unit (MORU) in Bangkok, Thailand.

The authors warned that malaria parasites resistant to both artemisinin and its widely used partner drug piperaquine are now spreading quickly throughout Cambodia, with fitter multidrug resistant parasites spreading throughout western Cambodia, southern Laos and northeastern Thailand.

"It has also picked up resistance to the partner drug piperaquine, causing high failure rates of the widely used artemisinin combination therapy DHA-piperaquine" Dondorp noted.

"We hope this evidence will be used to reemphasize the urgency of malaria elimination in the Asia-region before falciparum malaria becomes close to untreatable," Dondorp added.

After examining blood spot samples from patients with uncomplicated falciparum malaria from sites in Cambodia, Laos, Thailand and Myanmar, the study team found that PfKelch13 C580Y, a single mutant parasite lineage, has spread across three countries, replacing parasites containing other, less ACT-resistant mutations.

"The consequences of resistance spreading further into India and Africa could be grave if drug resistance is not tackled from a global public health emergency perspective," said Mahidol University Professor Nicholas White.