Microscopically, the presence of prominent, large schizont-containing phagocytic cells within and often occluding the lumens of vessels in the lung and spleen is considered pathognomonic. Differential diagnosis for this phase should include Haemobartonella felis, Babesia felis, Howell-Jolly bodies, or stain precipitate. The leukocytic or tissue phase must be distinguished from Toxoplasma, Leishmania, and Histoplasma. Organisms are best seen in Wright's or Giemsa-stained thin blood smears or impression smears of the spleen. In domestic cats, cytauxzoonosis is almost universally fatal, although some cats survive for unknown reasons.
Immunocompetence appears to influence the outcome of cytauxzoonosis in bobcats.
In these animals, the disease is generally benign, but may be fatal if the animal is stressed by capture or transport. Protective immunity against apicomplexan hemoparasites requires specific T-cell cytotoxicity with resultant killing of infected leukocytes and erythrocytes. Garner MM, Lung NP, et al. W.B. Saunders Company. The pathology of experimental Cytauxzoonosis.