Cytauxzoonosis is a protozoal disease of cats that is caused by Cytauxzoon felis.1-3 The organism is believed to be transmitted from bobcats, the primary reservoir host, to domestic cats via a tick vector.4,5 Because of the typical induction of a rapidly fatal illness, the domestic cat has been considered an accidental, dead-end host for this infectious agent.2,3
Cytauxzoon felis is associated with both a tissue (or schizogenous) phase and an intraerythrocytic phase that correlate with the clinical signs of severe circulatory impairment and hemolytic anemia, respectively. Typical clinical manifestations include signs of depression and lethargy, anorexia, fever, and jaundice. Cats often rapidly succumb to the disease, dying within < 1 week from initial onset of clinical signs.1,6,7 However, some cats survive infection with C felis and, after clinical recovery, may remain nonclinical carriers for months to years.8-10
Initial diagnosis can be made by microscopic visualization of round signet ring–like piroplasms within erythrocytes or schizont-laden macrophages in tissue aspirates, impression specimens, or peripheral blood smears. Because the tissue phase occurs prior to the erythrocytic phase, some cats can be severely ill but not have detectable parasites in their RBCs. The diagnosis can also be confirmed by characteristic histopathologic findings following necropsy. The pathophysiology of feline cytauxzoonosis mainly involves occlusion of small vessels with large histiocytic, schizont-filled macrophages in the lungs, spleen, and liver.11
Originally reported in domestic cats from southwestern Missouri in 1976,1 cytauxzoonosis has since been reported in many of the south central and southeastern states.12-16 To the authors' knowledge, there are no previously published reports of C felis infection in the mid-Atlantic region of the United States. Prior to 1998, the NCSU-VBDDL had not diagnosed C felis infection in cats or had consultations requested in relation to cytauxzoonosis in cats in North Carolina. Over the past several years, the NCSU-VBDDL has consulted with increasing numbers of veterinarians or owners regarding C felis infections in cats in North Carolina, Virginia, and South Carolina. Consequently, the purpose of the study reported here was to describe the demographic and clinical characteristics of cytauxzoonosis in cats in the mid-Atlantic states and compare the C felis 18S rRNA gene sequences from affected cats with sequences reported from affected cats in other regions of the United States.
North Carolina State University Vector Borne Disease Diagnostic Laboratory
Qiagen, Valencia, Calif.
Applied Biosystems, Foster City, Calif.
pGEM-T Easy Vector Systems, Promega, Madison, Wis.
JM109 high-efficiency competent cells, Promega, Madison, Wis.
LI-COR Inc, Lincoln, Neb.
Epicentre, Madison, Wis.
Hybaid, Franklin, Mass.
Bioedit, Raleigh, NC.
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