Protozoan Plasmodium falciparum inside red blood cells, illustration. P. falciparum is the causative agent of Malignant Tertian Malaria, also known as tropical malaria, the most severe form of malaria. It is transmitted to humans by the bite of female Anopheles mosquito. The illustration shows typical morphological features of P. falciparum in the stage of ring form (early trophozoite). It often has multiple rings with circle configuration (one chromatin dot) or headphone configuration (two chromatin dots), both configurations have small vacuoles and scanty cytoplasms.