Plasmodium knowlesi: an update

There were only four species of Plasmodium that were \nthought to cause malaria in humans until a large number \nof human infections by Plasmodium knowlesi, a malaria \nparasite typically found in long-tailed and pig-tailed macaques, \nwerereported in2004in Malaysian Borneo. Since then, \ncases of knowlesi malaria have been reported throughout \nSouth-east Asia and also in travellers returning from the \nregion. This article describes the molecular, entomological \nand epidemiological data which indicate that P. knowlesi is \nan ancient parasite that is primarily zoonotic, and there are \nthree highly divergent sub-populations. It also describes the \ndetection methods for P. knowlesi, which is morphologicaly \nsimilar to P. malariae, and the clinical features and treatment \nof this malaria parasite that is potentially fatal.