Movatterモバイル変換


[0]ホーム

URL:


Jump to content
WikipediaThe Free Encyclopedia
Search

Cytauxzoonosis

From Wikipedia, the free encyclopedia
Species of protozoan

Cytauxzoonosis
Scientific classificationEdit this classification
Domain:Eukaryota
Clade:Diaphoretickes
Clade:SAR
Clade:Alveolata
Phylum:Apicomplexa
Class:Aconoidasida
Order:Piroplasmida
Family:Theileriidae
Genus:Cytauxzoon
Species:
C. felis
Binomial name
Cytauxzoon felis
(Kier)
Synonyms[1]
  • Theileria felis

Cytauxzoon felis is aprotozoal organism transmitted to domesticcats bytick bites, and whosenatural reservoir host is thebobcat.[2][3][4][5]C. felis has been found in other wildfelid species such as thecougar, as well as awhite tiger in captivity.[6][7][8]C. felis infection is limited to the familyFelidae which means thatC. felis poses nozoonotic (transmission to humans) risk or agricultural (transmission to farm animals) risk. Until recently it was believed that after infection withC. felis, pet cats almost always died. As awareness ofC. 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.[2][5][9][10] New treatments offer as much as 60% survival rate.[11]

Terminology

[edit]

Cytauxzoon felis belongs to the orderPiroplasmida and the familyTheileriidae.[4]C. felis is related toTheileria spp. of Africanungulates. It is not abacterium, not avirus, and not afungus, but is instead aprotozoan that infects the blood cells of cats.[citation needed]

Epidemiology

[edit]

The first case ofC. felis was documented inMissouri in 1976, and in the past it was believed to be limited to south central and southeasternUnited States.[4] There have been more cases popping up in themid-Atlantic region in the United States, and even as far north asPennsylvania andNorth Dakota in bobcats.[2] 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.[2] 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.[4]

Symptoms and signs

[edit]

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 oflethargy andinappetence within 5 to 20 days after the tick bite.[4] 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 mucous membranes,respiratory distress,tachycardia orbradycardia, and tick infestation (although ticks are not often found on infected cats since cats typically groom ticks off their fur). Signs of disease seen on blood work includehemolytic anemia,thrombocytopenia, increased or decreasedwhite blood cell numbers, icterus, and elevatedliver enzymes. Death usually follows the onset of clinical signs within a few days.[4] However, more recent studies show not all cats develop clinical signs after infection, and some cats survive the infection.[2][5][9][10][11]

Life cycle and transmission

[edit]

The life cycle forCytauxzoon felis has not been completely described. Bobcats become persistent carriers of the organism after they develop mild or subclinical infection and then serve as the reservoir host.[2][3][4][5]C. felis is transmitted by the Lone star tick (Amblyomma americanum) that feeds on an infected bobcat then transmits the organism to another bobcat, or to a pet cat.[10] Many other types of ticks may feed on the cats, but the only other tick that has been shown to transmit the organism is the American dog tick (Dermacentor variabilis) but only in a research setting.[2][5][10] In the past, domestic cats were thought to always die from infection so they were considered terminal hosts or "dead end hosts".[4] Now there have been documented cases of cats that get sick and survive the infection and even those that never show clinical signs at all.[2][5][9][10] Cats cannot catch the infection from another cat directly without being bitten by a tick.[citation needed]

The life cycle of the protozoa has a tissue phase and anerythrocytic (red blood cell) phase. The organism goes throughasexual reproduction phase that is calledschizogony which occurs in the mononuclear phagocytic cells. In the tissue phase, the macrophage cells that are infected often clogvenules in organs such as the liver, spleen, lungs, and lymph nodes. It is this phase that is associated with clinical disease if the schizonts are numerous. Schizonts next form merozoites that break out of themacrophage cells and infect the red blood cells (erythrocytes). The erythrocytic disease is not as important for clinical disease, but is often used to diagnoseC. felis becausepiroplasms (erythrocytes that havephagocytizedmerozoites) can be seen on aperipheral blood smear under the microscope.[4]

It is not clear why some cats become clinically affected withC. felis while others never show any signs. There are speculations about resistance in some cats, and speculations about different strains ofC. felis with differing virulence.[2][11][12] There is not enough information to prove any of these theories, but cats in the same household or same regions can have drastically different clinical presentations. Some studies even show multi-cat households have had one cat die and another be persistently infected.[2][5] When cats survive infection they have persistentparasitemia which shows up in the blood as piroplasms, but these cats do not have the tissue phase again and therefore do not again show the clinical illness.[3][5][10]

Diagnosis

[edit]

One way to diagnoseC. felis is by taking blood and performing a peripheral blood smear to look for the erythrocytic piroplasms.[4] The erythrocytic piroplasms are usually shaped like signet rings and are 1 to 1.5 μm.[4] Not all cats that are infected will have the piroplasms on their blood smear, especially if they are early in disease course. Another method of diagnosing infection in sick cats is to take needle aspirates of affected organs and find the schizonts inside mononuclear cells in the tissues; examination of tissue is also useful for the diagnosis after cats have died. Blood samples can be sent away forpolymerase chain reaction (PCR) testing to confirm infection. Other diseases that might resemble cytauxzoonosis should be ruled out. A major rule-out forC. felis isMycoplasma haemofelis (formerly known asHaemobartonella felis); clinical signs can be similar to cytauxzoonosis and the organism may be confused on the peripheral smear.[4] Because it causes similar signs in outdoor cats during the spring and summer,tularemia is another disease the veterinarian may want to rule out.[citation needed]

Other laboratory tests are often abnormal in sick cats. TheCBC of an infected cat often shows apancytopenia, or a decrease in red blood cells, white blood cells, andplatelets; in some cases there is not a decrease in all three values.Clotting tests may be prolonged. Increased liver enzymes are common, andelectrolyte disturbances,hyperglycemia, and acid-base disturbances can also be observed.[citation needed]

Treatment and prevention

[edit]

The preventative measure of keeping cats inside in areas with high infection rates can prevent infection.[4] Approved tick treatments for cats can be used but have been shown not to fully prevent tick bites.[citation needed]

The most often used treatments for cytauxzoonosis areimidocarb dipropionate and a combination ofatovaquone andazithromycin. Although imidocarb has been used for years, it is not particularly effective.[13] In a large study,[13] only 25% of cats treated with this drug and supportive care survived. 60% of sick cats treated with supportive care and the combination of theanti-malarial drug atovaquone and the antibiotic azithromycin survived infection.[13]

Quick referral to a veterinarian equipped to treat the disease may be beneficial. All infected cats require supportive care, including careful fluids, nutritional support, treatment for complications, and oftenblood transfusion.[11]

Cats that survive the infection should be kept indoors as they can be persistent carriers after surviving infection and might indirectly infect other cats after being themselves bitten by a vector tick.[3][5]

References

[edit]
  1. ^"Cytauxzoon felis".CABI. Retrieved14 January 2019.
  2. ^abcdefghijBirkenheuer, A.J.; Le, J.A.; Valenzisi, A.M.; Tucker, M.D.; Levy, M.G.; Breitschwerdt, E.B. (2006). "Cytauxzoon felis in cats in the mid-Atlantic states: 34 cases (1998-2004)".Journal of the American Veterinary Medical Association.228 (4):568–571.doi:10.2460/javma.228.4.568.PMID 16478435.
  3. ^abcdBrown, H.M.; Latimer, K.S.; Erikson, L.E.; Cashwell, M.E.; Britt, J.O.; Peterson, D.S. (2008)."Detection of PersistentCytauxzoon Felis Infection by Polymerase Chain Reaction in Three Asymptomatic Domestic Cats".Journal of Veterinary Diagnostic Investigation.20 (4):485–488.doi:10.1177/104063870802000411.PMID 18599854.
  4. ^abcdefghijklmCohn, L.A. (2005). "Feline Cytauxzoonosis".American Association of Feline Practitioners Rounds.27:69–75.
  5. ^abcdefghiHabera, M.D.; Tuckera, M.D.; Marra, H.S.; Levyb, J.K.; Burgessc, J.; Lappind, M.R.; Birkenheuera, A.J. (2007). "The detection of Ctyauxzoon felis in apparently healthy free-roaming cats in the US".Veterinary Parasitology.146 (3–4):316–320.doi:10.1016/j.vetpar.2007.02.029.PMID 17391852.
  6. ^Garner, M.M.; Lung, N.P.; Citino, S.; Greiner, E.C.; Harvey, J.W.; Homer, B.L. (1996)."Fatal Cytauxzoonosis in a Captive reared White Tiger (Panthera tigris)".Veterinary Pathology.33 (1):82–86.doi:10.1177/030098589603300111.PMID 8826011.S2CID 10450447.
  7. ^Kier, A.B.; Wightman, S.R.; Wagner, J.E. (1982). "Interspecies transmission of Cytauxzoon felis".Am J Vet Res.43 (1):102–105.PMID 6807139.
  8. ^Rotstein, D.S.; Taylor, S.K.; Harvey, J.W.; Bean, J. (1999)."Hematologic effects of cytauxzoonosis in Florida panthers and Texas cougars in Florida".Journal of Wildlife Diseases.35 (3):613–617.doi:10.7589/0090-3558-35.3.613.PMID 10479103.S2CID 30210414.
  9. ^abcMeinkoth, J.; Kocan, A.A.; Whitworth, L.; Murphy, G.; Fox, C.; Woods, J.P. (2000). "Cats Surviving Natural Infection with Cytauxzoon felis: 18 Cases (1997-1998)".J Vet Med.14 (5):521–525.doi:10.1892/0891-6640(2000)014<0521:csniwf>2.3.co;2.PMID 11012116.
  10. ^abcdefReichard, M.V.; Meinkoth, J.H.; Edwards, A.C.; Snider, T.A.; Kocan, K.M.; Blouin, E.F.; Little, S.E. (2009). "Transmission of Cytauxzoon felis to a domestic cat by Amblyomma americanum".Veterinary Parasitology.161 (1–2):110–115.doi:10.1016/j.vetpar.2008.12.016.PMID 19168288.
  11. ^abcdCohn, L.A.; Birkenheuer, A.J.; Brunker J.D.; Ratcliff E.R.; Craig, A.W. (2011)."Efficacy of Atovaquone and Azithromycin or Imidocarb Dipropionate in Cats with Acute Cytauxzoonosis".J Vet Intern Med.25 (1):55–60.doi:10.1111/j.1939-1676.2010.0646.x.PMID 21143646.
  12. ^Brown, H.M.; Berghaus, R.D.; Latimer, K.S.; Britt, J.O.; Rakich, P.M.; Peterson, D.S. (2009)."Genetic Variability of Cytauxzoon felis from 88 Infected Domestic Cats in Arkansas and Georgia".Journal of Veterinary Diagnostic Investigation.21 (1):59–63.doi:10.1177/104063870902100109.PMID 19139502.
  13. ^abcCohn, L.A.; Birkenheuer, A.J.; Brunker, J.D.; Ratcliff, E.R.; Craig, A.W. (2011)."Efficacy of Atovaquone and Azithromycin or Imidocarb Dipropionate in Cats with Acute Cytauxzoonosis".J Vet Intern Med.25 (1):55–60.doi:10.1111/j.1939-1676.2010.0646.x.PMID 21143646.

External links

[edit]
Cytauxzoon felis
Retrieved from "https://en.wikipedia.org/w/index.php?title=Cytauxzoonosis&oldid=1254895133"
Categories:
Hidden categories:

[8]ページ先頭

©2009-2025 Movatter.jp