Dermacentor variabilus is the only known tick vector. The life cycle for the parasite is similar to that of Theileria spp except schizogony occurs in endothelial macrophages of blood vessels. Only transstadial transmission is known. Clinical signs in infected cats are typical of any infection that results in a hemolytic crisis such as anorexia, labored breathing, lethargy, dehydration, depression, icterus, and fever. The entire course of the clinical infection lasts less than 7 days.
Diagnosis is by the detection of pyroplasms in circulating erytrhocytes.
Giemsa stained impression smears of lung, liver, spleen, etc. are the best tissues. No treatment has proven effective against this organism. Supportive care may extend the clinical period but only 2 confirmed cases of recovery are documented. Tick control is important in preventing exposure. Recent changes in both demographics and living preferences have influenced both animal and human tick-transmitted disease prevelance.