New Drug-Resistant Malaria Strains Are Spreading in Southeast Asia

New drug-resistant strains of malaria parasites are spreading in Southeast Asia, according to twin studies published in The Lancet earlier this week. These new strains are prevalent particularly in Cambodia, Laos, Vietnam, and Northern Thailand.

After analyzing blood samples of malaria patients across Southeast Asia, the studies reveal that up to 80 percent of malaria parasites are now resistant to the two most common antimalarial drugs, artemisinin and piperaquine.

Before this, the most recent strain of drug-resistant malaria parasites spread in Western Cambodia around 2008.

From that original strain, a new subgroup mutated to form a stronger resistance and is fast overtaking the original’s numbers particularly in Cambodia, Laos, and Vietnam.

A drug combination named DHA-PPQ (dihydroartemisinin-piperaquine) was initially effective against the parasite before doctors noticed signs of resistance in 2013. In a recent study of the drug, DHA-PPQ reached a 62 percent failure rate in western Cambodia, 53 percent in southwestern Vietnam, and 87 percent in northeastern Thailand.

“Strains resistant to artemisinin and piperaquine are becoming more widespread,” Rob W. van der Pluijm MD, of the Mahidol-Oxford Tropical Medicine Research Unit, and one of the studies’ authors, told The Lancet in a podcast interview. “It also clearly shows that these strains are not just spreading but are also becoming the predominant strain in the region.”

Although the studies’ findings raise alarm, this doesn’t mean the disease is untreatable. According to van der Pluijm, a combination of the drugs used for treatment could overcome the parasites’ resistance. But a pressing concern is whether these strains will spread to areas where the malaria burden is heavier, such as Africa and India.

“This highly successful resistant parasite strain is capable of invading new territories and acquiring new genetic properties, raising the terrifying prospect that it could spread to Africa, where most malaria cases occur, as resistance to chloroquine did in the 1980s, contributing to millions of deaths," Prof Olivo Miotto, one of the papers’ authors, told BBC.

An estimated 219 million people were infected with malaria in 2017, an two million increase from 2016, according to the World Health Organization's World Malaria Report. 435,000 people have died from the disease that year.