Malaria drug resistance
Increasing drug resistance is a major impediment to effective malaria control in the WHO Western Pacific Region. Resistance of Plasmodium falciparum to older antimalarial drugs, including chloroquine and sulfadoxine/pyrimethamine, was first recognized in the Greater Mekong Subregion (GMS) in the 1970s. Currently, varying degrees of resistance to these drugs are reported throughout the Region.
In 2003, the WHO Regional Office for the Western Pacific undertook a review of national malaria drug policies and both published and unpublished studies from the past 10 years on antimalarial drug efficacy in all endemic countries of the Region. The review showed that a network of sentinel sites to monitor drug resistance is already in operation in the GMS countries, as well as in Malaysia and the Philippines, but needs to be established in Papua New Guinea, Solomon Islands and Vanuatu. In general the available drug efficacy data in the studies reviewed were not sufficient and their quality varied greatly. The report will soon be available and will include a database with all available studies from the 10-year review.
The use of artemisinin-based combination therapy (ACT) was pioneered in the Region early 1990s in response to the spread of malaria drug resistance. Currently, ACT is established as a first-line therapy in Cambodia and Viet Nam. The introduction of ACT is under way in the Lao People’s Democratic Republic and is under consideration in Malaysia and in several Pacific island countries and areas including Papua New Guinea, Solomon Islands and Vanuatu. ACT is the second-line drug in China and the Philippines.
Substandard and counterfeit antimalarial drugs are increasingly found in countries of the Region, especially in the Greater Mekong Subregion. To combat counterfeit pharmaceuticals, regional and national approaches are necessary, including law enforcement and drug registration and inspection. Heightened public awareness of the problem among consumers and health care providers urgently needs to be stepped up. To halt the spread of antimalarial drug resistance, it is crucial that effective antimalarial drugs be available for populations most at risk and that antimalarial drugs be used rationally. Public and the private sector initiatives are under way in the Region to address the problem, including village malaria worker projects in Cambodia and Viet Nam, and the social marketing of malaria rapid diagnostic tests and ACT in the private sector in Cambodia.