Feline Cytauxzoon (Cytauxzoonosis) Symptoms and Treatments

Cytauxzoonosis is a serious, often fatal, protozoal disease affecting domestic cats in the south central and southeastern portions of the United States. The causative organism, Cytauxzoon felis, is classified in the Order Piroplasmida, Family Theileridae. Because of the rapid onset of severe clinical illness and high mortality (historically greater than 95%) associated with this disease in domestic cats, they likely serve as accidental dead-end hosts. The natural reservoir host of Cytauxzoon felis is the North American bobcat (Lynx rufus).

In most instances, bobcats remain asymptomatic when infected by Cytauxzoon felis; however, fatal infection also has been observed in this species. Ticks are believed to be the natural vector for this organism. Experimentally, an Ixodid tick (Dermatocentor variablis) has been shown to transmit Cytauxzoon felis from bobcats to domestic cats, causing the clinical signs associated with cytauxzoonosis. As expected, cytauxzoonosis is seen more often during the summer months (May through September) when ticks are more likely to be found. Cats with access to the outdoors (especially wooded areas) are at higher risk of coming into contact with infected ticks and acquiring this disease.

Cytauxzoon felis is a one-celled parasite that infects cats. The life cycle has not been fully researched, but the parasite is believed to be spread by ticks. Cats are thought to be accidental hosts, i.e., not the usual host. It is diagnosed by seeing the organism in blood cells examined microscopically.

It infects blood cells, and cells of the liver, lungs, spleen, and lymph nodes. The signs and symptoms of disease include listlessness, anemia, difficulty breathing, high fever, and jaundice. It is almost always fatal, and the cat dies in less than 14 days from the time the symptoms start. Until recently, there has been no known effective treatment; diminazene aceturate and imidocarb dipropionate have successfully treated a small number of cats. Intravenous fluids and other supportive care are also necessary.

Because there is no cure, tick prevention is extremely important. Products which contain the ingredients pyrethrin or fipronil are good choices. You may also want to keep your cat indoors during the tick season.

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