Plasmodium knowlesi in a traveller returning to New Zealand.

The recent discovery that Plasmodium knowlesi causes malaria in human populations, established it as the fifth species of plasmodium that may do so. A case of P. knowlesi malaria is described in a helicopter pilot from New Zealand, who became ill after returning from recurring visits to Malaysian Borneo in June 2010. His P. knowlesi infection was not detected using microscopic examination and a rapid diagnostic test for malaria, but was confirmed by both PCR (polymerase chain reaction) and sequence analysis showing homology with the ribosomal RNA gene for P. knowlesi. He responded rapidly to treatment with artemether & lumefantrine combination. The evolution of a rapid diagnostic kit to diagnose P. knowlesi is needed, for early identification and appropriate anti-malarial therapy of suspect cases are both critical in the prevention of the potentially life-threatening disease through P. knowlesi. Clinicians need to consider knowlesi infection in the differential diagnosis in recent-onset febrile travellers to areas of forestation in Southeast Asia.