Q&A-Why are experts worried about a possible new strain of drug-resistant malaria?

via CAAI News Media

08 Mar 2010
Written by: Thin Lei Win

A health worker checks a blood sample for malaria in the only hospital in Pailin in western Cambodia. Bordering with Thailand, this former Khmer Rouge stronghold and dusty gem mining town is now better known for a malarial parasite that is worrying health experts in the region. Studies and research show artemisinin-based therapies - currently the most effective treatment against malaria - are taking longer to cure some of the patients. REUTERS/Damir Sagolj

PAILIN, Cambodia (AlertNet) - A number of studies have shown that in areas along the Thai-Cambodia border, conventional malaria-fighting treatments derived from artemisinin took almost twice as long to clear the parasites that cause the disease, suggesting the drugs were losing potency in the area.

The studies shine a spotlight on the remote province of Pailin, the origin of three drug-resistant malaria parasites over the past five decades.

Artemisinin-based combination therapies (ACT) are currently the most effective treatment against P. falciparum, the most lethal type of malaria.

Here are some questions and answers about the subject:

WHAT IS DRUG RESISTANCE AND WHAT CAUSES IT?

When a parasite survives and/or multiplies despite the patient receiving and absorbing the drug given in doses equal to or higher than those usually recommended, drug resistance occurs. It can cause malaria treatment to fail.

Using sub-standard or counterfeit drugs, incorrect dosage or in the case of artemisinin, using it alone, can all cause resistance.

WHY IS PAILIN A BREEDING GROUND FOR SUCH PARASITES?

As one of the Khmer Rouge's last battlegrounds, the small province covering 1,066 sq km was a difficult place for locals to access healthcare. In the past, its dense jungles created the perfect breeding ground for mosquitoes and the booming gem mines of the 1980s and 1990s brought an influx of foreign migrants with low immunity.

Often, they did not seek treatment in public health facilities, preferring over-the-counter medicines which led to drug resistance.

Today, few gem mines are left but many domestic migrants still move in and out of Pailin, working as odd job labourers in agricultural and construction sectors.

WHY ARE MALARIA EXPERTS SO WORRIED ABOUT THIS STRAIN?

Dr. John MacArthur, chief of the President's Malaria Initiative at the U.S. Centres for Disease Control and Prevention said: "The U.S. government and other donor nations are spending millions and millions rolling out these ACTs and what we're now concerned about is that history will repeat itself with resistant strains migrating from Asia thus rolling back the significant gains that have been made in malaria control in Africa."

If the current strain of the artemisinin-resistant parasite spreads like it did 50 years ago to Africa, where most of the malaria burden lies, and make ACTs useless, the global ramifications could be huge.

According to the World Health Organisation (WHO), beyond the human toll, malaria causes a decrease Gross Domestic Product (GDP) by as much as 1.3 percent in countries with high levels of transmission.

WHAT IS BEING DONE TO STOP THIS PARASITE FROM SPREADING?

The Bill and Melinda Gates Foundation is funding a $22.5 million containment programme -- the first of its kind -- led by WHO and a few other organisations to ensure the parasite does not go beyond Thai-Cambodia border.

The programme faces numerous challenges however, including reaching and monitoring a mobile population not reflected in official records, enforcing the ban on monotherapy and counterfeit drugs in Cambodia's many unlicensed drug stores, and shortcomings on different screening methods.

HAVE THE PARASITES SPREAD TO OTHER COUNTRIES?

So far, health care experts have expressed worries about the parasites being present along the Thai-Myanmar, Vietnam-Cambodia and Myanmar-China borders but there has been no confirmation.

Late last year, Malaria Consortium warned the parasites may be spreading to other parts of Southeast Asia.

"Nobody can say how long it will take for the parasite to spread," Dr. Chansuda Wongsrichanalai of USAID's infectious disease team in Bangkok said. "If there's a big movement of people then it will surely escalate the situation."

ARE THERE ANY ALTERNATIVES TO ACTS?

There are no real alternatives to ACTs currently. The only non-ACT in the market currently is malarone. However, its pricey tag and vulnerability - atovaquone, a component of malarone, is said to be even easier to develop resistance according to USAID -- makes it impractical for large-scale public health programmes.

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