After injection into the vertebrate host the parasite migrates to endothelial cells of the capillaries.

An apical complex is present which includes a polar ring and rhoptries but lacks a conoid.

The clinical manifestations of this disease are anaemia, jaundice, fever, hepatomegaly, splenomegaly, lymphadenopathy, haematochezia and persistent bleeding from the nose, oral cavity and the tips, margins and outer surface of the pinnae.

These include regenerative anaemia, spherocytosis, icteric plasma, leukopenia due to neutropenia, thrombocytopenia, eosinopenia and bilirubinuria.

Langhans type multinucleate giant cells may be present in the lymph nodes and the choroid plexus.