[Human natural infection of Plasmodium knowlesi].

A blood film slide taken from a patient previously diagnosed as vivax malaria in Mojiang County, Yunnan Province, showing atypical forms. The ring forms had multinuclei, and the late trophozoites trended to form band. The schizonts and gametocytes were somewhat alike to Plasmodium vivax. PCR amplification confirmed that the patient was infected by P. knowlesi.