The hotbed of antimalarial resistance (including artemesin) has been the Greater Mekong subregion comprising of Cambodia, Lao People’s Democratic Republic, Myanmar, Thailand and Viet Nam. We have always been concerned about artemesin resistance spilling across the north eastern border of India from South East Asian region. Before this report there has been no evidence of artemesin resistance in India.
This study reports the same from West Bengal by studying the parasite clearance half-life, kelch13 mutations, and survival of malarial parasites in clinical isolates from April 2013 to March 2014. The authors defined artemesin resistance based on the WHO definition: presence of parasitemia at 72 hours (±2 hours) after treatment + with a parasite-clearance half-life of more than 5 hours + persistence of a parasite survival rate greater than 10% (on the basis of ex vivo RSA0-3h), + presence of a mutation in kelch13 distal to codon 440 (i.e., in the DNA sequence encoding the propeller domain).
Of the 136 isolates from patients with uncomplicated falciparum malaria, 15% showed findings suggestive of artemesin tolerance with 5 patients having accompanying Kelch 13 mutations. Kelch13 G625R is a novel mutation reported in this study. Notably, at least four of the 20 drug-resistant patients identified in West Bengal had traveled to Southeast Asia at some point. None of the patients had clinical failure due to effective combination therapy with artemether-lumefantrine and longer doses of artesunate. Hope the resistant parasite does not travel further into India.