Susceptibility of human plasmodium knowlesi infections to anti-malarials

Farrah A. Fatih, Henry M. Staines, Angela Siner, Mohammed Atique Ahmed, Lu Chan Woon, Erica M. Pasini, Clemens H. M. Kocken, Balbir Singh, Janet Cox Singh, Sanjeev Krishna*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

34 Citations (Scopus)
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Background: 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.

Methods: 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.

Results: Plasmodium knowlesi is uniformly highly sensitive to artemisinins, variably and moderately sensitive to chloroquine, and less sensitive to mefloquine.

Conclusions: 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.

Original languageEnglish
Article number425
Number of pages7
JournalMalaria Journal
Publication statusPublished - 19 Nov 2013


  • Artemisinin
  • Artemether
  • Artesunate
  • Dihydroartemisinin
  • DHA
  • Chloroquine
  • Mefloquine
  • Malaria
  • In-vitro
  • Mefloquine resistance
  • Vivax malaria
  • PFMDR1 gene
  • Falciparum
  • Malaysia
  • Sensitivity
  • Sabah
  • Erythrocytes
  • Adaptation


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