Artemisinin resistant Malaria strain reported in Africa

Almost 3.2 billion people (virtually half the world’s population) in 89 countries are at risk of contracting Malaria. Every year, over 200 million cases and over 400,000 deaths are recorded.

For more than 15 years, treatment of malaria episodes (typical cycles of the disease alternating between fever, shivering and chills, and severe sweating) caused by Plasmodium falciparum has depended on artemisinin-based combination therapies (ACTs), which combine a fast-acting artemisinin derivative and a partner drug with a long half-life.

[Artemisia annua]

Resistance to artemisinin, the main component of the current antimalarial treatments recommended by WHO, is already widespread in South-East Asia, but it had not previously been described in Africa. A major concern is that these resistant parasites will spread through Sub-Saharan Africa, the continent most affected by malaria (>90% of all cases).

Since 2008, parasites capable of resisting artemisinin derivatives in South-East Asia have become increasingly prevalent. This resistance, which leads to a delay in the clearance of parasites from the bloodstream of individuals treated with an ACT, is currently a serious threat that may hinder efforts to tackle the disease.

Since 2014, the distribution of artemisinin resistance has been monitored based on the detection of mutations in parasites. Currently, the most widespread resistant parasites in South-East Asia have the C580Y mutation[1]. Recently, C580Y mutant parasites have also been detected in Guyana and Papua New Guinea.

[Plasmodium falciparum]

Scientists recently identified the first signs of emergence of artemisinin-resistant mutant parasites in Africa. The results describe significant proportions of parasites carrying the R561H mutation in two locations 100 kilometers apart[2]. Whole-genome sequencing of these parasites indicates that the R561H mutants were, unexpectedly, not acquired from Asian parasites.

The fact, that this resistant strain has spread between several places in Rwanda and its ability to resist artemisinin in vitro, has major public health implications. There is a risk that over time they will acquire the ability to resist the partner drugs used in ACTs. This would mean that the only available treatments would become ineffective, as has occurred in South-East Asia.

[1] Zaw et al: Importance of kelch 13 C580Y mutation in the studies of artemisinin resistance in Plasmodium falciparum in Greater Mekong Subregion in Journal of Microbiology, Immunology and Infection – 2019. See here.
[2] Uwimana et al: Emergence and clonal expansion of in vitro artemisinin-resistant Plasmodium falciparum kelch13 R561H mutant parasites in Rwanda in Nature Medicine – 2020. See here.