Plasmodium knowlesi

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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Marjan Khan M.B.B.S.[2]

Plasmodium knowlesi
Scientific classification
Kingdom: Protista
Phylum: Apicomplexa
Class: Aconoidasida
Order: Haemosporida
Family: Plasmodiidae
Genus: Plasmodium
Species: P. knowlesi
Binomial name
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,[1][2] particularly Malaysia,[3] but there are also reports on the Thai-Burmese border.[4] A fifth of the cases of malaria diagnosed in Sarawak, Malaysian Borneo are due to P. knowlesi.[3]
  • 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[5]. 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,[6] it is not normally attracted to humans and therefore cannot be an important vector for transmission.[7]

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 [3]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.[3]

Plasmodium knowlesi genome data

References

  1. Chin W, Contacos PG, Coatney RG, Kimbal HR. (1965). "A naturally acquired quotidian-type malaria in man transferable to monkeys". Science. 149: 865. PMID 14332847.
  2. Yap FL, Cadigan FC, Coatney GR. (1971). "A presumptive case of naturally occurring Plasmodium knowlesi malaria in man in Malaysia". Trans R Soc Trop Med Hyg. 65 (6): 839&ndash, 40. PMID 5003320.
  3. 3.0 3.1 3.2 3.3 Singh B, Lee KS, Matusop A, Radhakrishnan A, Shamsul SSG, Cox-Singh J, Thomas A, Conway DJ (2004). "A large focus of naturally acquired Plasmodium knowlesi infections in human beings". Lancet. 363: 1017&ndash, 24. doi:10.1016/S0140-6736(04)15836-4.
  4. Jongwutiwes S, Putaporntip C, Iwasaki T, Sata T, Kanbara H. (2004). "Naturally acquired Plasmodium knowlesi malaria in human, Thailand". Emerg Infect Dis. 10 (12): 2211&ndash, 3. PMID 15663864.
  5. Vythilingam I, Tan CH, Asmad M, Chan ST, Lee KS, Singh B. (2006). "Natural transmission of Plasmodium knowlesi to humans by Anopheles latens in Sarawak, Malaysia". Trans R Soc Trop Med Hyg. 100: 1087&ndash, 88. doi:10.1016/j.trstmh.2006.02.006.
  6. Wharton RH, Eyles DE. (1961). "Anopheles hackeri, a vector of Plasmodium knowlesi in Malaya". Science. 134: 279&ndash, 80.
  7. Reid JA, Weitz B. (1961). "Anopheline mosquitoes as vectors of animal malaria in Malaya". Ann Trop Med Parasitol. 55: 180&ndash, 6.

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