Antimalarial drug resistance

To date, parasite resistance to antimalarials has been documented in three of the five malaria species known to affect humans: P. falciparum, P. vivax and P. malariae. Parasite resistance results in a delayed or incomplete clearance of parasites from the patient’s blood when the person is being treated with an antimalarial.

The problem of antimalarial drug resistance is compounded by cross resistance, in which resistance to one drug confers resistance to other drugs that belong to the same chemical family or which have similar modes of action. During the past decades, several antimalarials had to be removed from markets after spread of parasite resistance.

Artemisinin-based combination therapies

Today, WHO recommends artemisinin-based combination therapies (ACTs) for the treatment of uncomplicated malaria caused by P. falciparum. ACTs have been integral to the remarkable recent successes in global malaria control, and there is broad consensus that protecting the efficacy of these medicine combinations is an urgent priority.

However, P. falciparum resistance is now emerging to artemisinin having detected in five countries of the Greater Mekong Subregion: Cambodia, the Lao People’s Democratic Republic, Myanmar, Thailand and Viet Nam. Containment activities are ongoing in all countries as part of a multi-stakeholder effort.

Global plan for artemisinin resistance containment

The emergence of P. falciparum resistance to artemisinin is an urgent public health concern, threatening the sustainability of the global effort to reduce the malaria burden in all endemic regions. In January 2011, WHO released the Global plan for artemisinin resistance containment (GPARC), which puts forward four main goals and recommendations:

  • to stop the spread of resistant parasites
  • to increase monitoring and surveillance to evaluate the artemisinin resistance threat
  • to improve access to diagnostics and rational treatment with ACTs; and
  • to invest in artemisinin resistance-related research.

The GPARC calls on endemic countries and stakeholders to scale up containment activities in affected countries, and to implement comprehensive plans in other endemic regions to prevent the emergence of resistance.

Prevention and containment

Prevention and containment activities need to build on, expand and accelerate ongoing national efforts to control and eliminate malaria. Artemisinin resistance seems to be occurring primarily near national borders, and in areas with a high number of migrants; therefore strong cross-border and regional programmes are central to continued success in the fight against malaria. WHO is currently implementing an emergency response plan to scale-up containment efforts in the Greater Mekong Subregion, and has opened a regional hub in Phnom Penh, Cambodia to spearhead the multi-partner effort.

Last updated: 6 March 2014

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