Assessment of artemisinin tolerance in Plasmodium falciparum clinical isolates in children with uncomplicated malaria in Ghana

• Published in: Malaria Journal
• Main Authors: Samuel Yao Ahorhorlu, Neils Ben Quashie, Rasmus Weisel Jensen, William Kudzi, Edmund Tetteh Nartey, Nancy Odurowah Duah-Quashie, Felix Zoiku, Bartholomew Dzudzor, Christian William Wang, Helle Hansson, Michael Alifrangis, George Obeng Adjei
• Format: Article in Journal/Newspaper
• Language: English
• Published: BMC 2023
• Subjects: Artemisinin tolerance; Plasmodium falciparum; Uncomplicated Malaria; Ex vivo ring-stage survival assay; Kelch 13; Pfcoronin; Arctic medicine. Tropical medicine; RC955-962; Infectious and parasitic diseases; RC109-216; Arctic
• Online Access: https://doi.org/10.1186/s12936-023-04482-w; https://doaj.org/article/0f1bf3d93df0480cbd14c851c58ddac4

Abstract Background Artemisinin-based combination therapy (ACT) is the first-line treatment for uncomplicated malaria in Ghana. Artemisinin (ART) tolerance in Plasmodium falciparum has arisen in Southeast Asia and recently, in parts of East Africa. This is ascribed to the survival of ring-stage parasites post treatment. The present study sought to assess and characterize correlates of potential ART tolerance based on post-treatment parasite clearance, ex vivo and in vitro drug sensitivity, and molecular markers of drug resistance in P. falciparum isolates from children with uncomplicated malaria in Ghana. Methods Six months to fourteen years old children presenting with acute uncomplicated malaria (n = 115) were enrolled in two hospitals and a Health Centre in Ghana’s Greater Accra region and treated with artemether-lumefantrine (AL) according to body weight. Pre- and post-treatment parasitaemia (day 0 and day 3) was confirmed by microscopy. The ex vivo ring-stage survival assay (RSA) was used to detect percent ring survival while the 72 h SYBR Green I assay was used to measure the 50% inhibition concentration (IC50s) of ART and its derivatives and partner drugs. Genetic markers of drug tolerance /resistance were evaluated using selective whole genome sequencing. Results Of the total of 115 participants, 85 were successfully followed up on day 3 post-treatment and 2/85 (2.4%) had parasitaemia. The IC50 values of ART, artesunate (AS), artemether (AM), dihydroartemisinin (DHA), amodiaquine (AQ), and lumefantrine (LUM) were not indicative of drug tolerance. However, 7/90 (7.8%) pre-treatment isolates had > 10% ring survival rates against DHA. Of the four isolates (2 RSA positive and 2 RSA negative) with high genomic coverage, P. falciparum (Pf) kelch 13 K188* and Pfcoronin V424I mutations were only present in the two RSA positive isolates with > 10% ring survival rates. Conclusions The observed low proportion of participants with day-3 post-treatment parasitaemia is consistent with rapid ART clearance. ...