Artemisinin combination therapy fails even in the absence of Plasmodium falciparum kelch13 gene polymorphism in Central India
Sabyasachi Das, Amrita Kar, Subhankar Manna, Samaresh Mandal, Sayantani Mandal, Subhasis Das, Bhaskar Saha, Amiya Kumar Hati
Abstract
Abstract Artemisinin is the frontline fast-acting anti-malarial against P. falciparum . Emergence and spread of resistant parasite in eastern-India poses a threat to national malaria control programs. Therefore, the objective of our study is to evaluate the artesunate-sulfadoxine-pyrimethamine efficacy in Central India. 180 monoclonal P. falciparum -infected patients received standard ASSP therapy during August 2015–January 2017, soon after diagnosis and monitored over next 42-days. Artemisinin-resistance was assessed through in-vivo parasite clearance half-life (PC 1/2 ), ex-vivo ring-stage survivability (RSA), and genome analysis of kelch13 and other candidate gene ( pfcrt, pfmdr1, pfatpase 6, pfdhfr and pfdhps ). Of 180 P. falciparum positive patients, 9.5% showed increased PC 1/2 (> 5.5 h), among them eleven isolates (6.1%) showed reduced sensitivity to RSA. In 4.4% of cases, parasites were not cleared by 72 h and showed prolonged PC 1/2 (5.6 h) (P < 0.005) along with significantly higher RSA (2.2%) than cured patients (0.4%). None of day-3 positive isolates contained the pfkelch13 mutation implicated in artemisinin resistance. Parasite recrudescence was observed in 5.6% patients, which was associated with triple dhfr – dhps (A 16 I 51 R 59 N 108 I 164 –S 436 G 437 K 540 G 581 T 613 ) combination mutation. Emergence of reduced sensitivity to artesunate-sulfadoxine-pyrimethamine, in central India highlighted the risk toward spread of resistant parasite across different parts of India. Day-3 positive parasite, featuring the phenotype of artemisinin-resistance without pfkelch13 mutation, suggested kelch13 -independent artemisinin-resistance.