Ashley and colleagues have recently published work in the New England Journal of Medicine showing an increase in resistance of Falciparum malaria to the most effective remaining agent: artemisinin.
The mechanism of resistance to artemisinin is conferred by a single point mutation of the “kelch” protein on chromosome 13 in Plasmodium falciparum.
What is scary about this is that resistance has been reported in many countries across mainland Southeast Asia – from Bangladesh to Thailand and Vietnam. Resistance evolution has also occurred in equatorial Africa.
There is wide variation in the parasite clearance rate when treated with artemisinin at these locations, from 1.9 hours to 7 hours along the Cambodia Thai border. Cambodia is one of the first sites where artemisinin resistance was detected.
Slow parasite clearance means some malaria is surviving treatment, increasing the risk of transmission of those strains. It is also worrisome that the increased survival of these parasites may offer a window of opportunity for selection to favor additional mutations giving the parasites an even greater ability to survive in the presence of the drug.