Images of Memorable Cases: Case 79 Peripheral blood film from a 60-year-old hunter with headache, malaise, anorexia, and low-grade fever of two weeks’ duration. 79. Babesiosis The diagnosis of this tick-borne disease depends on finding the causative protozoan in the peripheral blood film. In this patient, the film shows dumbbell-shaped markings in red blood cells, findings characteristic of Babesia species (image below, arrows). Not surprisingly, the blood film findings of babesiosis simulate those of Plasmodium falciparum malaria.