Vectors
Theoretically there are four modes of transmission: from an infected monkey to another monkey, from an infected monkey to a human, from an infected human to another human and from an infected human back to a monkey. In practice human malaria appears to be almost entirely due to monkey to human transmission.
The known vectors belong to the genus Anopheles, subgenus Cellia, series Neomyzomyia and group Leucosphyrus. Mosquitoes of this group are typically found in forest areas in South East Asia but with a greater clearing of forest areas for farmland, humans are increasingly becoming exposed to these vectors.
Within the monkey population in Peninsular Malaysia, Anopheles 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 seems unlikely to be an important vector for transmission to humans.
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.
Anopheles cracens has also been reported as a vector of P. knowlesi. Both species of mosquitoes have been shown to contain as many as 1,000 sporozoites suggesting that they may be efficient vectors.
A study of potential vectors in Malayasia suggests that Anopheles cracens may be an important vector of P. knowlesi.
Read more about this topic: Plasmodium Knowlesi