Babesiosis: malaria mimic.

Human infection with blood parasites of the genus Babesia can result in a hemolytic disease very similar to malaria. Laboratory diagnosis of babesiosis is dependent upon the detection and identification of the parasite in blood films. The distinguishing criteria are: lack of pigment in infected red blood cells; no circulating schizonts or gametocytes; "atypical" malarialike organisms; tetrad groups, rods, or exclamation-mark forms; and persisting parasitemia after treatment for malaria.