Study Finds Advantage in Anti-Malaria Therapy Used in Cambodia


By David McFadden

December 15, 2005


A new study from researchers at the Pasteur Institute network states that global misuse of the most crucial anti-malaria medication is allowing mosquitoes to develop strong resistance to the drug in certain countries, but that blood samples taken in Cambodia showed no sign of resistance.

Blood samples taken from malaria patients in French Guiana and Senegal, where use of the anti-malarial drug artemisinin is uncontrolled and used alone in treatment, showed signs that the malaria parasite was insensitive to the drug.

But in Cambodia, where artemisinin is controlled and used in conjunction with the drug mefloquine, blood samples taken for the same study showed signs of the drug’s continued effectiveness against malaria.

“If you use only one [drug] the chances of decreased sensitivity are greater,” said Frederic Ariey, a malaria specialist at the Phnom Penh office of the Pasteur Institute.

“The Ministry of Health uses two drugs in Cambodia and every year they test for good treatment,” he said.

Ariey said that mutation in a gene in the malaria parasite, Plasmodium falciparum, which is targeted by the drug artemisinin, has not been observed in Cambodia.

“Until now we haven’t seen any decreased sensitivity [in artemisinin],” he said.

Duong Socheat, director of the National Malaria Center and adviser to the Ministry of Health, said that coordination of combined drug therapy has helped keep resistance to the first-line malaria treatment at bay.

Artesunate, a water-soluble form of artemisinin, has been effectively used in combination therapies to battle malaria in Cambodia for roughly four years.

“There is no monotherapy used in Cambodia as they do in other countries, so we have not seen resistance,” Duong Socheat said.

Guidelines to aid early diagnosis and treatment of malaria in Cambodia are updated at two-year intervals based on the results of drug-resistance monitoring and cost-effectiveness studies, according to Duong Socheat.

Currently, national malaria treatment guidelines for uncomplicated cases of malaria recommend a combination of artesunate with mefloquine as a first-line treatment and a combination of the drugs quinine and tetracycline as a second-line treatment.

Malaria treatment and control are hampered by the spread of resistance to common antimalarial drugs, especially along the Cambodia-Thai border where multi-drug resistant malaria is highly prevalent, according to the National Malaria Center’s strategic plan for 2006-2010.

The release of the Pasteur research, which was published rescently in a British medical journal, follows a call by the World Health Organization in September that urged all malaria-affected countries to be careful in their use of artemisinin-based drugs to avoid resistance to the treatment.

“All resistant [samples] came from areas with uncontrolled use of artemisinin derivatives,” said Ronan Jambou, lead scientist in the research.