News that resistance to artemisinin combination drugs – the frontline response against malaria – is spreading has spurred debate on whether a new approach is needed to counter the disease and other serious threats to human health.
Leading malaria scientists revealed last week that alarming failure rates had been encountered in new areas in Southeast Asia where health workers are treating people for the disease.
They warned that a “superbug” – malaria parasites highly resistant to artemisinin and the partner drug piperaquine – originally identified in western Cambodia, has now also spread to southern Vietnam.
Artemisinin drug-resistant P falciparum C580Y mutant malaria parasites have now spread across the entire Mekong sub-region, the scientists said in a letter to ‘The Lancet Infectious Diseases‘.
‘Superbug’ now in southern Vietnam
“A single mutant strain of very drug-resistant malaria has now spread from western Cambodia to northeastern Thailand, southern Laos and into southern Vietnam and caused a large increase in treatment failure of patients with malaria,” said Oxford Prof Arjen Dondorp, deputy head of the Mahidol Oxford Tropical Medicine Research Unit (MORU) in Bangkok, said.
This could jeopardize current efforts to eliminate malaria in the region, Prof Dondorp said. “This superbug is spreading quickly,” he said. “Elimination is now a race against the clock, before malaria becomes very difficult to treat.”
Resistance to artemisinin, which was highly successful in bringing down malaria deaths around the world, was first noted in Pailin in western Cambodia nine years ago.
“Around 700,000 people a year die from drug-resistant infections, including malaria. If nothing is done, this could increase to millions of people every year by 2050.”
World health authorities recognized the threat and international donors ramped up funding of malaria elimination efforts in Southeast Asia amid concern that loss of the frontline drug could leave malaria untreatable.
Prof Dondorp said the Global Fund had made $100 million in funding available over the past three years, plus a further $243 million for five countries – Vietnam, Cambodia, Laos, Thailand and Myanmar – over the next three years.
An aggressive campaign to try to eliminate falciparum malaria has been waged via networks of community volunteers in all these five countries in the Greater Mekong Subregion, armed with rapid diagnostic tests and treatment kits.
But the outlook was clouded by the spread of resistance to artemisinin and some partner drugs.
Dondorp’s colleague at MORU, Sir Nicholas White said the “alarming rise in treatment failures is forcing changes in drug policy and leaving few options for the future.”
Michael Chew, from Wellcome’s Infection and Immunobiology team, said the spread of the ‘superbug’ strain, resistant to the most effective anti-malaria drug, had huge implications for public health globally.
“Around 700,000 people a year die from drug-resistant infections, including malaria. If nothing is done, this could increase to millions of people every year by 2050,” he said.
‘Endless chase for new drugs doomed to fail’
William Aldis, a former country director in Thailand for the World Health Organization, said the endless chase for development of new anti-malarial agents – and antibiotics – seemed doomed to failure, and the primary beneficiary would be the pharmaceutical industry.
“In the case of malaria, progress will depend on study of the biology of the vector – the mosquito – and of the infectious agent/s (plasmodium species). At present, this work is in an early stage, but you can get an idea where it’s headed by checking out the website of the Johns Hopkins Malaria Research Institute, one the lead institutions working on biological approaches.
There were a range of possibilities, Aldis said – intervening at the level of the mosquito, the infectious agent (plasmodium) or “the mosquito-human interface” (when people get bitten).
“Maybe we need to produce DNA-edited mosquito strains which are malaria-resistant and which can compete with native mosquitoes in the environment.”
Similar thinking could be applied to bacterial infections, he said, but the number of intervention points may be fewer.