Cytauxzoon felis is a protozoal organism transmitted to domestic cats by tick bites, and whose natural reservoir host is the bobcat. C. felis has been found in other wild felid species such as the cougar, as well as a white tiger in captivity. C. felis infection is limited to the family Felidae which means that C. felis poses no zoonotic (transmission to humans) risk or agricultural (transmission to farm animals) risk. Until recently it was believed that after infection with C. felis, pet cats almost always died. As awareness of C. felis has increased it has been found that treatment is not always futile. More cats have been shown to survive the infection than was previously thought. New treatments offer as much as 60% survival rate. Terminology Cytauxzoon felis belongs to the order Piroplasmida and the family Theileriidae. C. felis is related to Theileria spp. of African ungulates. It is not a bacterium, not a virus, and not a fungus, but is instead a protozoan that infects the blood cells of cats. Epidemiology The first case of C. felis was documented in Missouri in 1976, and in the past it was believed to be limited to south central and southeastern United States. There have been more cases popping up in the mid-Atlantic region in the United States, and even as far north as Pennsylvania and North Dakota in bobcats. There has not been any age or sex predilection made, but intact animals have shown more prevalence in some studies; in particular intact males. In studies it is unclear if the sex predilection is due to the increased roaming of intact animals or another reason. The most common seasons for the disease to become apparent are spring and summer and appear to affect outdoor cats the most often. The reason that outdoor cats get infected more is due to the increased exposure to ticks. Ticks are also active in spring and summer. Symptoms and signs Most infected cats have been healthy before a very sudden onset of severe disease. The course of clinical disease is often swift with clinical signs of lethargy and inappetence within 5 to 20 days after the tick bite. Cats develop a high fever, but the temperature may become low before death. Other clinical findings can be: dehydration, icterus (jaundice), enlarged liver and spleen, lymphadenopathy, pale mucus membranes, respiratory distress, tachycardia or bradycardia, and tick infestation (although