First identified in 1948, Cytauxzoon spp are protozoal hemoparasites of wild and domestic cats.
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First identified in 1948, Cytauxzoon spp are protozoal hemoparasites of wild and domestic cats.
Definition
Geographic Distribution
Signalment
Risk Factors
Pathophysiology
Figure 1A. Blood film from a cat at 10¥ magnification. There is a moderate decrease in red cell mass (anemia) and thrombocytopenia. The leukocyte count is decreased, and neutrophils exhibit Döhle bodies and increased cytoplasmic basophilia and vacuolation consistent with moderate to marked toxic change (broken arrows). Small basophilic inclusions are present within erythrocytes (solid arrows). Courtesy of IDEXX Laboratories
Figure 1B. Same blood film at higher magnification (40¥). Erythrocytes show several small signet-ring basophilic intracellular organisms consistent with Cytauxzoon organisms (arrows). Courtesy of IDEXX Laboratories
The erythrocyte form, referred to as a piroplasm, often develops late in the course of disease, can vary in severity, and may not develop in some cases. Clinical signs of cytauxzoonosis are often due to the schizogonous phase, and schizont-laden macrophages can be found in any tissue throughout the body. The infected macrophages become enlarged and occlude the blood vessels, making this tissue form much more pathogenic.13
Signs
Definitive Diagnosis
Laboratory Findings
Imaging
Cytology
PCR Assay
Histopathology
The Rare Recovery
Figure 2A. Distended hepatic vein with luminal macrophages (magnification, 10¥). Courtesy of IDEXX Laboratories
Figure 2B.Same image at higher magnification (40¥) shows schizont-laden macrophage (arrows) within the lumen of a hepatic vein in a cat diagnosed with Cytauxzoon felis infection. Courtesy of IDEXX Laboratories
Inpatient
Medications
Nutritional Management
Relative Cost
Cost Key | |
$= up to $100 | $$$$= $501-$1000 |
$$= $101-250 | $$$$$= more than $1000 |
$$$= $251-$5000 |
Prognosis
Prevention
Future Considerations
Thoughts on Cytauxzoon felis
Cats were dying—and dying quickly. At first veterinarians thought they were dealing with hemobartonellosis, but postmortem examination revealed the disease was something quite different.
These cases, reported in 1976, dealt with adult cats dying after development of anemia, icterus, dehydration, and fever, followed by rapid progression to death and the finding of schizonts and merozoites in various tissues. Characteristic tissue phases of Cytauxzoon spp were found in samples from cats sent to University of Missouri.
Impression smear of the liver of an experimentally infected cat shows schizonts containing macrophages (arrows). Normal hepatocytes can also be seen (arrowhead).
Peripheral blood smear from a cat with cytauxzoonosis with piroplasms in several erythrocytes.
Within 6 years, this previously unrecognized disease had been reported not only in Missouri but also in numerous southeastern states. It was unknown whether the disease had been introduced only recently in the United States, represented new exposure of pet cats to wildlife parasites because of encroachment into wildlife habitats, or represented a change in virulence of the parasite.1,2 Because the first Cytauxzoon spp recognized were pathogens of ruminants in Africa, there was concern as to whether this disease represented a threat to food animals. A significant amount of work was done to determine the host range and pathogenicity of the parasite. After a variety of wildlife had been inoculated (as well as farm and laboratory animals) with whole blood from cats affected by terminal cytauxzoonosis, the organism was found to parasitize only domestic and wild cats, specifically bobcats.1,2 Early transmission studies typically were done by inoculating animals with peripheral blood or homogenates of spleen, lung, or lymph nodes from infected animals. Ticks serve as the natural vector for transmission of closely related organisms, and it was soon shown that Dermacentor variabilis was a competent vector of the disease. It has since been shown that Amblyomma americanum is also a competent vector and most likely the primary vector of C felis in nature.
The range of C felis follows that of the bobcat, and disease in cats has currently been identified in the south-central, southeastern, and mid-Atlantic United States. Research continues to determine why some cats survive this disease and others do not, in addition to developing advanced diagnostic techniques and determining the best treatment options.3 - Patricia Thomblison, DVM, MS (Parasitology)
Joanna K. Fry, DVM, is a second-year internal medicine resident at Gulf Coast Veterinary Specialists in Houston, Texas. Dr. Fry’s clinical interests include endocrinology, gastroenterology, and immune-mediated diseases. Dr. Fry received her DVM from Ohio State University and after completing a 1-year rotating internship at MedVet Medical and Cancer Center for Pets in Worthington, Ohio, finished a 1-year internal and emergency medicine internship at Affiliated Animal Care in Chesapeake, Virginia.
References
References
1. Distribution and prevalence of Cytauxzoon felis in bobcats (Lynx rufus), the natural reservoir, and other wild felids in thirteen states. Shock BC, Murphy SM, Patton LL, et al. Vet Parasitol 175:325-330, 2011.
2. Cytauxzoon felis infections are present in bobcats (Lynx rufus) in a region where cytauxzoonosis is not recognized in domestic cats. Birkenheuer AJ, Marr HS, Warren C, et al. Vet Parasitol 153:126-130, 2008.
3. Fatal cytauxzoonosis in a free ranging bobcat (Lynx rufus). Nietfeld JC, Pollock C. J Wildl Dis 38:607-610, 2002.
4. Hematologic effects of cytauxzoonosis in Florida panthers and Texas cougars in Florida. Rotstein DS, Taylor SK, Harvey JW, Bean J. J Wildl Dis 35:613-617, 1999.
5. Cytauxzoonosis in bobcats. Glenn BL, Kocan AA, Blouin EE. JAVMA 183:1155-1158, 1983.
6. Administration of diminazene aceturate or imidocarb dipropionate for treatment of cytauxzoonosis in cats. Greene CE, Latimer K, Hopper E, et al. JAVMA 215:497-500, 482, 1999.
7. Detection of persistent Cytauxzoon felis infection by polymerase chain reaction in three asymptomatic domestic cats. Brown HM, Latimer HS, Erikson LE, et al. J Vet Diagn Invest 20:485-488, 2008.
8. The detection of Cytauxzoon felis in apparently healthy free-roaming cats in the USA. Haber MD, Tucker MD, Marr HS, et al. Vet Parasitol 146:316-320, 2007.
9. A fatal cytauxzoonosis-like disease in cats. Wagner JE. JAVMA 168:585, 1976.
10. The pathology of experimental cytauxzoonosis. Kier AB, Wagner JE, Kinden DA. J Comp Pathol 97:415-432, 1987.
11. Cytauxzoon felis infection in cats in the mid-Atlantic states: 34 cases (1998-2004). Birkenheuer AJ, Le JA, Valenzisi AM, et al. JAVMA 228:568-571, 2006.
12. Genetic variability of Cytauxzoon felis from 88 infected domestic cats in Arkansas and Georgia. Brown HM, Berghaus RD, Latimer KS, et al. J Vet Diagn Invest 21:59-63, 2009.
13. Cytauxzoonosis in domestic cats: Report of two cases in Oklahoma, with a review and discussion of the disease. Glenn BL, Stair EL. JAVMA 184:822-825, 1984.
14 Feline cytauxzoonosis: A case report and literature review. Meier HT, Moore LE. JAAHA 36:493-496, 2000.
15. Efficacy of atovaquone and azithromycin or imidocarb dipropionate in cats with acute cytauxzoonosis. Cohn LA, Birkenheuer AJ, Brunker JD, et al. J Vet Intern Med 25:55-60, 2010.
16. Fatal cytauxzoonosis in a Kentucky cat. Jackson CB, Fisher T. Vet Parasitol 139:192-195, 2006.
17. Cats surviving natural infection with Cytauxzoon felis: 18 cases (1997-1998). Meinkoth J, Kocan AA, Whitworth L, et al. J Vet Intern Med 14:521-525, 2000.
18. Feline cytauxzoonosis. Meinkoth JH, Kocan AA. Vet Clin North Am Small Anim Pract 35:89-101, 2005.
19. Temporal occurrence and environmental risk factors associated with cytauxzoonosis in domestic cats. Reichard MV, Baum KA, Cadenhead SC, et al. Vet Parasitol 152:314-320, 2008.
20. Cytauxzoon sp. infection in the first endemic focus described in domestic cats in Europe. Carli E, Trotta M, Chinelli R, et al. Vet Parasitol 183:343-252, 2012.
THOUGHTS ON CYTAUXZOON FELIS • Patricia Thomblison
1. Hematological findings in experimental cytauxzoonosis. Franks PT, Harvey JW, Shields RP, et al. JAAHA 24:395-401, 1988.
2. Feline cytauxzoonosis. Meinkoth JH, Kocan AA. Vet Clin North Am Small Anim Pract 35:89-101, 2005.
3. Efficacy of atovaquone and azithromycin or imidocarb dipropionate in cats with acute cytauxzoonosis. Cohn LA, Birkenheuer AJ, Brunker JD, et al. J Vet Intern Med 25:55-60, 2011.
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