Kingdom fights to prevent drug-resistant malaria

Brett Worthington | 09 Feb 2009
The Phnom Penh Post
Despite recent studies pointing to the potential spread of drug-resistant malaria, the World Health Organisation remains optimistic that proper administration of the antimalarial drug artemisinin can fend off resistance and contain the disease.

Pascal Ringwald, malaria coordinator for the WHO, told the Post last week that widespread use of artemisinin in a combination, or co-formulated, pill is central to its proper administration.

Ringwald acknowledged that two studies - including one published last December in The New England Journal of Medicine - concluded that artemisinin has become less effective but dismissed the idea that drug-resistant malaria strains are likely to spread.

The study notes that artemisinin resistance "does not seem to be a widespread epidemiologic phenomenon at this time". "There are some cases [of resistance], but they have been contained," Ringwald said. "We have the combination drug that still works."

Artemisinin is designed to be taken with a drug that stays in the blood longer and clears out residual malaria parasites, Ringwald said, noting that the risk of resistance developing rises when the drug is administered without the partner drug. "The delay in eradication is due to monotherapies still being on the market," he said.

While resistance does not develop overnight, Duong Socheat, director of the National Centre for Parasitology, Entomology and Malaria Control, said a proactive approach was essential to counter it.

He said artemisinin resistance would lead to more malaria fatalities because "we cannot find a new drug".

Cautious optimism

According to multiple research papers, a decade ago more than 1,000 people died each year in the Kingdom from malaria, but efforts to control the disease have seen the number of annual fatalities drop to less than 200.

Despite this progress, the recent studies point out that the threat of resistance remains.

Ringwald said the global community has been slow to respond to indications that resistance could be on the rise. Since 2000, he said, artemisinin has grown less and less effective.

"In 2001 we endorsed co-formulated pills, but companies invested in monotherapies," he said. "It has only been in recent times that more companies have begun producing co-formulated therapies."

Its delayed response aside, Duong Socheat said the medical community has learned from past instances of resistance to other antimalarial drugs, particularly chloroquine, which was first administered in the 1940s. Resistance developed in the 1950s and ultimately spread widely enough to render the drug essentially ineffective.

One of the factors that damaged the effectiveness of chloroquine was over-prescription, he said. To avoid this in the case of artemisinin, doctors are also prescribing Malarone, which can be used both as a preventive drug and as a form of treatment, Duong Socheat said.

A three-day conference held last week in Phnom Penh was the first of four organised in conjunction with the Bill and Melinda Gates Foundation, which has pledged US$14 million to the Cambodian and Thai governments to help with containment efforts.

With an eradication plan in place, Doung Sochet said he is cautiously optimistic about stopping transmission of the disease from mosquitos to humans.

Ringwald said the implementation of and adherence to strict protocols - in particular, the pairing of artemisinin with partner drugs - would likely control the disease.

"In a wonderful world, the combined drugs would slow down the parasite," he said. "But we also need to continue our containment work."