Multidrug-resistant forms of malaria-causing parasites are spreading across Southeast Asia, leading to “alarmingly high” treatment failure rates of frontline medication, researchers warned Tuesday.
Twin studies published in The Lancet Infectious Diseases journal revealed that in parts of Thailand, Vietnam and Cambodia, up to 80% of the most common malaria parasites were now resistant to the two most common antimalarial drugs. In Thailand’s northeast, a once-reliable combination treatment has been failing in nearly nine out of 10 cases, according to recent data.
The Plasmodium falciparum parasites have also acquired resistance linked to the failure of treatment in half of cases to one of the newest and most potent frontline drug combinations, they said.
“These worrying findings indicate that the problem of multidrug resistance in P falciparum has substantially worsened in southeast Asia since 2015,” said Olivo Miotto from the Wellcome Sanger Institute and University of Oxford, who co-led the study.
“This highly successful resistant parasite strain is capable of invading new territories and acquiring new genetic properties.”
He warned of the “terrifying prospect” of the parasite spreading to Africa, where most malaria cases occur.
A similar resistance to a long-time frontline malaria drug, chloroquine, contributed to millions of deaths across Africa in the 1980s.
More than 200 million people are infected with the P falciparum parasite, which is responsible for nine out of 10 malaria deaths globally.
A drug combination known as DHA-PPQ was initially effective against the parasite, before doctors noticed signs of resistance in 2013.
The most recent study into DHA-PPQ failure rates showed they have now reached 53 percent in southwest Vietnam, and as high as 87 percent in northeastern Thailand.