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Plasmodium falciparum and artemisinin combination therapies

Artemisinin Combination Therapies are currently the frontline treatments against Plasmodium falciparum malaria. Although these treatments are working well in many parts of the world, there is serious concern that malaria parasites are once again developing widespread resistance to this vital treatment.

History of Plasmodium falciparum drug resistance

P. falciparum resistance to chloroquine, the former recommended treatment against P. falciparum malaria, first emerged in the late 1950s in Southeast Asia; it then spread or emerged to other countries in Asia, and then on to Africa over the next thirty years with devastating consequences.

Based on research evidence, resistance to sulfadoxine-pyrimethamine (SP), another leading therapy against malaria, originated in the same region of South East Asia, spreading even more rapidly to Sub-Saharan Africa.

Mefloquine resistance appeared in Thailand, Cambodia, and Vietnam – countries where it was widely used – within five years of its introduction in the 1990’s.

Resistance to artemisinin combination therapies

In recent years the rate of those falling ill and dying from malaria infection has decreased significantly. This is accredited to increased investment in prevention and treatment measures including insecticide-treated bed nets and the use of the highly successful Artemisinin Combination Therapies.

However, these recent life-saving gains are under threat due to the emergence and spread of artemisinin drug resistance in many parts of Southeast Asia. The Tracking Resistance to Artemisinin Collaboration (TRAC) is researching clinical, molecular, pharmacokinetic and socio-economic aspects of artemisinin resistance. The team found that malaria drug resistance to the widely used artemisinin-based therapies was firmly established in Western Cambodia, Thailand, Vietnam, Eastern Myanmar and Northern Cambodia, with signs of resistance emerging in Central Myanmar, Southern Laos and Northeastern Cambodia.

We are beginning to see the past repeat itself. If this drug resistance spreads further afield or emerges in Africa then millions of lives will be at risk.

Preventing further spread and emergence

Containing antimalarial drug resistance in Southeast Asia – and preventing the spread of resistance through Asia to Africa and beyond – is a global public health priority. The WHO Global Action Plan for Artemisinin Resistance Containment (GPARC) was published in 2011, and outlines comprehensive recommendations for the containment of drug resistance.

Continuous monitoring of drug resistance in malaria-endemic countries along with research into the various contributing factors will enable health authorities and practitioners to more effectively prevent drug resistance from spreading.

A major focus of resistance containment activities is in ceasing the use of artemisinin-based monotherapies. In Southeast Asia, where there is relatively low transmission of malaria, containment programmes aim to accelerate the elimination of P. falciparum parasites. Elimination of the parasites would be the ideal way to stop the spread of resistance entirely. In areas where there is high malaria transmission, decreasing the risk of a spread of resistance is possible through an increase in malaria control efforts.