Patients with malaria areg treated at the hospital in Pailin, Cambodia, Aug. 26, 2009.

Som Aun contracted malaria after moving to the Thma Baing district of Cambodia's Koh Kong province in 2002. Four years later, two of his children contracted the disease.

For five years, his son, An, now 19, and daughter, Sreyna, now 12, remained infected because no effective treatment was available, he told VOA Khmer.

"Sometimes the disease is healed for o­ne month, but it would come back in the next two months," he said, adding they both exhibited high fevers and chills.

His children, who work in banana plantations, were in and out of clinics, and "after they took medicines, they would be fine for a period of time, then they would have to go to the hospital if they were in serious condition," Aun said. The family resorted to hospitals infrequently, because transportation cost 200,000 riel to 300,000 riel (or about $50 to $75).

Researchers are increasingly alarmed by the emergence of a strain of drug-resistant malaria in Cambodia, a so-called "superbug" that stares down the most commonly used anti-malaria drugs.

The superbug, first identified in 2008 in Cambodia, has spread into parts of Vietnam, Thailand and Laos. Last month, scientists from the Mahidol Oxford Tropical Medicine Research Unit (MORU) published a letter in The Lancet saying the superbug's spread throughout the Mekong area was a serious threat to malaria control and eradication.

"A single mutant strain of very drug resistant malaria has now spread from western Cambodia to north-eastern Thailand, southern Laos and into southern Vietnam and caused a large increase in treatment failure of patients with malaria," says letter co-author Arjen Dondorp, and Oxford professor, in a MORU release. MORU is a collaborative effort involving Thailand's Mahidol University, Oxford University and the U.K.-based Wellcome Trust.

A malaria patient rests in the o­nly hospital in Pailin, western Cambodia.

"We are losing a dangerous race," Nicholas White, o­ne of the letter's co-authors, said in the release. "The spread of this malaria 'superbug' has caused an alarming rise in treatment failures forcing changes in drug policy and leaving few options for the future."

Local officials not concerned

Huy Rekol, director of Cambodia's National Center for Parasitology, Entomology and Malaria Control (CNM), said he was not worried by the drug-resistant malaria.

"In our country, we don't need to worry about matters of death or resistance because we have efficient drugs to use every day," he said.

Malaria in Cambodia is caused by two types of viruses transmitted by female mosquitoes, according to the CNM. It identified several factors leading to a rise in malaria infections in 2015, including increasing mobility of people living in malaria-affected areas.

Rekol said that about 10,000 infections were detected in 2017, but all those identified as contracting malaria were treated. He said that any resistance was "manageable," adding that more should be done to prevent transmission in the first place.

Nguyen Thi Khe, a former official at the government Institute of Public Hygiene, told VOA Vietnamese that malaria was "not a serious issue in Vietnam right now," a sentiment that was repeated by other officials.

Dondorp said it was worrying that Cambodian malaria officials appeared to be unconcerned by the reports of drug resistance, which he said could undo the gains of recent years. "In northeastern Thailand, Srisaket province is affected, almost all of Cambodia is affected, as well as southern Laos, and South Vietnam," Dondorp said in an email to VOA.

In an email, he said, "The evolution and subsequent transnational spread of this single fit multidrug-resistant malaria parasite lineage is of international concern."

A risk to Africa?

Globally, an estimated 3.2 billion people in 95 countries and territories are at risk of being infected with malaria, according to the World Health Organization. Most of the deaths occur in Africa, and there, children age 5 and younger account for more than two-thirds of the deaths, according to WHO.

A village malaria worker shows his malaria medicine kit at O'treng village o­n the outskirts of Pailin, Cambodia, Aug. 29, 2009.

The big worry is that the new strain of malaria may spread from the Mekong area to Africa.

Dr. David Sullivan, an infectious disease expert at Johns Hopkins Bloomberg School of Public Health who is affiliated with its Malaria Research Institute, said health officials in Africa have been monitoring the situation for several years and that the new bug has yet to appear there.

But, Sullivan added, "in the age of global travel" he could not say there is "zero possibility" of it making the jump. However, "even if it does jump, it's not that super of a bug that it's going to leave us defenseless, as if we have no drugs at all for malaria."

An analysis conducted at the request of the Malaria Policy Advisory Committee (MPAC), WHO's top advisory committee for malaria, found that while "the risk of drug-resistant malaria spreading to India and Africa cannot be discounted, the broad consensus was that drug-resistant parasites were more likely to emerge independently in other parts of the world than to spread directly from" the Mekong region consisting of Cambodia, Lao People's Democratic Republic (PDR), Myanmar, Thailand and Viet Nam, according to Dr. Pedro Alonso, director of the Global Malaria Programme, in a Q&A published late last month on the committee's site.

Alonso said that WHO experts do not "at this time" consider "the threat of antimalarial drug resistance a public health emergency of international concern."

That drug-resistant malaria would emerge in Cambodia is not a surprise. "In the past 50 or 60 years, this is the fifth or sixth time this has happened," Sullivan said. "This is not new."

The new strain "is able to be tackled and held in check," he said. "I understand the concern and the alarm, but I would not put a superbug label o­n it, although I can see why people have."

"Treatment options for the new strain exist," Sullivan said, by either adding a drug to those usually prescribed, or extending the treatment duration of the current treatment.

Substandard drugs

Cambodia adopted o­ne treatment, to which resistance has apparently grown, but has since switched to another. The resistance was identified in the western Cambodian region of Pailin, later spreading to northeastern Thailand and southern Laos, according to the letter published by The Lancet.

Dondorp, deputy director of MORU, said in an email to VOA that resistance may have been encouraged by the use of substandard drugs to treat malaria.

"Malaria is a disease of the poor and disenfranchised. These are often populations living in border areas and in or near to the forest," he said.

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