Feline Cytauxzoonosis Study Guide

Overview and Clinical Importance

Cytauxzoonosis is a life-threatening, tick-borne protozoal disease of domestic and wild felids caused by Cytauxzoon felis. First described in Missouri in 1976, this disease has historically been considered uniformly fatal in domestic cats, with mortality rates approaching 100% without treatment. The disease is endemic to the south-central and southeastern United States, with geographic expansion correlating with the distribution of its primary tick vector, Amblyomma americanum (the Lone Star tick). Understanding this disease is critical for NAVLE success, as it represents a high-yield topic in feline emergency and infectious disease medicine.

Etiology and Taxonomy

Cytauxzoon felis is a tick-transmitted, obligate, hemoprotozoal piroplasmid pathogen belonging to the phylum Apicomplexa, order Piroplasmida, and family Theileriidae. The organism is closely related to Theileria species, which cause East Coast fever in cattle.

Taxonomic Classification

Life Cycle and Transmission

C. felis has a complex life cycle requiring both a tick (definitive host) and a felid (intermediate host). Understanding this cycle is essential for NAVLE questions on pathogenesis and prevention.