The challenge of drug resistance
Resistance of Plasmodium falciparum to malaria drugs is a major global problem. Plasmodium vivax has also developed resistance in some areas.
Drugs such as chloroquine and sulfadoxine-pyrimethamine once used commonly to treat falciparum malaria are now ineffective in most malaria endemic countries around the world. In recent years resistance to artemisinin, the most effective antimalarial currently available, has also emerged in the Greater Mekong Sub-region. Here, multi-drug resistant falciparum malaria is now widespread. Even more worryingly, the presence of ACT resistant parasites has recently been confirmed on the Thai Cambodia border.
Resistance to malaria drugs can be found at varying levels and low levels of resistance may not impact on control. Artemisinin and its derivatives, are not used alone for the treatment of uncomplicated malaria, but are combined with a partner drug; this is known as artemisinin-based combination therapy (ACT). Currently the level of artemisinin resistance means that ACT treatment can still be effective in these areas provided the partner drug is efficacious. However, there is a real and serious risk that drug resistance will worsen and spread further. ACT resistance has already been identified on the Thai-Cambodia border. Intense efforts by the global malaria control community are underway to attempt to halt the spread of these resistant parasites and to delay emergence of resistance elsewhere.
In some countries (e.g. Indonesia, Papua New Guinea and India) vivax malaria is also resistant to chloroquine. A further concern for vivax malaria is that primaquine (the drug used to effect a ‘radical’ cure of vivax malaria, destroying the dormant stages in the liver to avoid later relapse of the disease) appears to be less effective in Oceania.
ADDITIONAL RESOURCES
on malaria diagnosis, treatment and drug resistance