Drug-resistant malaria spreads across Asean

Only half of Asean’s patients with malaria are being cured because multi-drug resistant forms of the disease are spreading.

The Lancet Infectious Diseases published two related studies today (Tuesday) showing rising resistance to antimalarial drugs in the Plasmodium falciparum parasite could hamper efforts to control the disease and present a “major threat” to public health.

The P falciparum is the most deadly of the five parasites transmitted by mosquitoes that cause human malaria. It is responsible for 90 per cent of malarial deaths and around 200 million of the 217 million infections reported in 2017.

“These worrying findings indicate that the problem of multi-drug resistance in P falciparum has substantially worsened in south-east Asia since 2015,” said Olivo Miotto of 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.”

Malaria is not as prevalent in Asean as in Africa but the rise of resistance is a particular concern because it could spread elsewhere.

Similar resistance to a long-time frontline malaria drug, chloroquine, contributed to millions of deaths across Africa during the 1980s.

The trial looked at 140 patients who received malaria treatment in Cambodia, Thailand and Vietnam and found around half were not cured by first-line antimalarial drugs. The study said efforts to eliminate malaria in the countries must be accelerated.

“[The] expansion and further spread of very difficult to treat, highly resistant P falciparum would cause a regional and potentially global health emergency,” the study said.

Malaria kills more than 400,000 annually, mostly children in Africa.

A linked genetic study of the drug-resistant parasite said the mutation only emerged in Cambodia in 2008 and spread rapidly, especially since 2015.

A drug combination known as DHA-PPQ was initially effective against the parasite before medics noticed evidence of resistance in 2013.

The most recent study into DHA-PPQ failure rates showed they have now reached 53 per cent in southwest Vietnam and as high as 87 per cent in largely rural northeastern Thailand.

The study said between 2016 and 2018, more than 80 per cent of parasites found in northeast Thailand and Vietnam were drug-resistant.

“One thing that was particularly worrying is how fast the mutations have spread from Cambodia to neighbouring countries,” said Dr Roberto Amato from the Wellcome Sanger Institute.

“We discovered that the multi-drug resistant malaria strain had spread aggressively, replacing local malaria parasites, and had become the dominant strain in Vietnam, Laos and northeastern Thailand,” said Amato, a joint author of the study.

Picture credit: Wikimedia