Plasmodium knowlesi

Plasmodium knowlesi is a primate malaria parasite commonly found in Southeast Asia. It causes malaria in long-tailed macaques (Macaca fascicularis), but it may also infect humans, either naturally or artificially.

Epidemiology
Reports of human P. knowlesi infections are confined to Southeast Asia, particularly Malaysia, but there are also reports on the Thai-Burmese border. A fifth of the cases of malaria diagnosed in Sarawak, Malaysian Borneo are due to P. knowlesi.

P. knowlesi infection is normally considered an infection of long-tailed (Macaca fascicularis) and pig-tailed (M. nemestrina) macaques, but humans who work at the forest fringe or enter the rainforest to work are at risk of being infected with P. knowlesi. The mosquito Anopheles latens is attracted to both macaques and humans and has been shown to be the main vector transmitting P. knowlesi to humans in the Kapit Division of Sarawak, Malaysian Borneo''. Within the monkey population in Peninsular Malaysia, 'A. hackeri', is believed to be the main vector of 'P. knowlesi' : although 'A. hackeri' is capable of transmitting malaria to humans, it is not normally attracted to humans and therefore cannot be an important vector for transmission.

Diagnosis
P. knowlesi infections is diagnosed by examining thick and thin blood films in the same way as other malarias. The appearance of P. knowlesi is similar to that of P. malariae and is unlikely to be correctly diagnosed except by using molecular detection assays in a malaria reference laboratory. There are no ill effects of misdiagnosing P. knowlesi as P. malariae, because the treatment is the same.

Treatment
P. knowlesi infection responds well to treatment with chloroquine and primaquine.

Plasmodium knowlesi genome data

 * GeneDB Plasmodium knowlesi