Susceptibility of human Plasmodium knowlesi infections to anti-malarials

• Published in: Malaria journal Vol. 12; no. 1; p. 425
• Main Authors: Fatih, Farrah A, Staines, Henry M, Siner, Angela, Ahmed, Mohammed Atique, Woon, Lu Chan, Pasini, Erica M, Kocken, Clemens Hm, Singh, Balbir, Cox-Singh, Janet, Krishna, Sanjeev
• Format: Journal Article
• Language: English
• Published: England BioMed Central Ltd 19.11.2013; BioMed Central
• Subjects: Animals; Antimalarials; Antimalarials - pharmacology; Artemisinins - pharmacology; Borneo; Chloroquine - pharmacology; Colleges & universities; Dosage and administration; Drug resistance in microorganisms; Drug therapy; Erythrocytes; Health aspects; Humans; Infections; Malaria; Malaria - parasitology; Medical research; Medicine, Experimental; Mefloquine; Mefloquine - pharmacology; Microscopy; Parasites; Parasitic Sensitivity Tests; Patients; Plasmodium falciparum; Plasmodium falciparum - drug effects; Plasmodium falciparum - isolation & purification; Plasmodium knowlesi; Plasmodium knowlesi - drug effects; Plasmodium knowlesi - isolation & purification; Plasmodium vivax; Plasmodium vivax - drug effects; Plasmodium vivax - isolation & purification; Prevention; Zoonoses - parasitology; Borneo; United Kingdom; Netherlands; Malaysia; Sarawak Malaysia; Borneo, Sarawak
• ISSN: 1475-2875; 1475-2875
• DOI: 10.1186/1475-2875-12-425

Evidence suggests that Plasmodium knowlesi malaria in Sarawak, Malaysian Borneo remains zoonotic, meaning anti-malarial drug resistance is unlikely to have developed in the absence of drug selection pressure. Therefore, adequate response to available anti-malarial treatments is assumed. Here the ex vivo sensitivity of human P. knowlesi isolates in Malaysian Borneo were studied, using a WHO schizont maturation assay modified to accommodate the quotidian life cycle of this parasite. The in vitro sensitivities of P. knowlesi H strain adapted from a primate infection to in vitro culture (by measuring the production of Plasmodium lactate dehydrogenase) were also examined together with some assays using Plasmodium falciparum and Plasmodium vivax. Plasmodium knowlesi is uniformly highly sensitive to artemisinins, variably and moderately sensitive to chloroquine, and less sensitive to mefloquine. Taken together with reports of clinical failures when P. knowlesi is treated with mefloquine, the data suggest that caution is required if using mefloquine in prevention or treatment of P. knowlesi infections, until further studies are undertaken.