Plasmodium knowlesi

Last edited 12/2019 and last reviewed 02/2023

P. knowlesi

Practitioners should be aware of the recognition of P. knowlesi as the fifth malaria parasite of humans.

It is a parasite of macaques and a zoonosis in humans in the Asia-Pacific region.

As its asexual cycle takes only 24 hours, it is possible for its parasitaemia to rise more rapidly than with the other malaria species.

A further danger is its close morphological resemblance to P. malariae which is a much less severe infection

• therefore, P. knowlesi should be urgently considered in any patient with malaria from the Asia-Pacific region with what appears to be P. malariae
  
  
• whilst P. knowlesi is a zoonosis and thus not amenable to control in the same way as those parasites which infect humans alone, prevention of human infection still relies on bite prevention, awareness of risk and chemoprophylaxis. P. knowlesi is sensitive to chloroquine

Reference:

• Public Health England. Guidelines for malaria prevention in travellers from the UK 2019