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