| Line 3: |
Line 3: |
| | '''[[Babesia|''Babesia'']] | | '''[[Babesia|''Babesia'']] |
| | | | |
| | + | '''[[Cytauxzoon|''Cytauxzoon felis'']] |
| | | | |
| − | ==''Cytauxzoon felis''==
| |
| − |
| |
| − | *Cytauxzoon is classified in the order ''Piroplasmida'' and family ''Theileriidae''
| |
| − | **This family has both an erythrocytic and a tissue (leukocytic) phase
| |
| − |
| |
| − | *The ''Babesiidae'', a related family, is characterized by having a primarily erythrocytic phase in the mammalian host
| |
| − | **Its morphological features are indistinguishable from the erythrocytic form of Cytauxzoon
| |
| − |
| |
| − | *''Cytauxzoon felis'', ''B. equi'', and ''B. rodhaini'' have been linked to both the babesias and theilerias by RNA gene sequence analysis
| |
| − | **It has been suggested that these organisms be reclassified within a separate family
| |
| − |
| |
| − | '''Life Cycle'''
| |
| − | *Large schizonts of ''C. felis'' develop in [[Macrophages - WikiBlood|macrophages]]
| |
| − | **In Theileria the exoerythrocytic stage occurs primarily within [[Lymphocytes - WikiBlood|lymphocytes]]
| |
| − |
| |
| − | *In ''C. felis'', schizonts develop within mononuclear phagocytes, initially as indistinct vesicular structures and later as large, distinct nucleated schizonts that actively undergo division by true schizogony and binary fission
| |
| − |
| |
| − | *Later in the course of the disease, schizonts develop buds (merozoites) that separate and eventually fill the entire host cell
| |
| − |
| |
| − | *Each schizont may contain numerous merozoites
| |
| − | **Ultrastructurally, schizonts lack a parasitophorous vacuole, and individual merozoites possess rhoptries
| |
| − |
| |
| − | *The host cell ruptures, releasing merozoites into the tissue fluid and blood
| |
| − |
| |
| − | *Merozoites are then believed to enter erythrocytes to form the intraerythrocytic stage
| |
| − |
| |
| − | *Merozoites appear in [[Macrophages - WikiBlood|macrophages]] one to three days before they are observed in [[Erythrocytes - WikiBlood|erythrocytes]]
| |
| − |
| |
| − | '''Pathogenicity'''
| |
| − | *[[Ticks|Ticks]] are implicated as the natural vector for ''Cytauxzoon''
| |
| − | **Most cases of infection have been associated with the presence of these parasites on the hosts
| |
| − | **Experimentally, ''Dermacentor variabilis'' can transmit the organism from bobcats to domestic cats. In a white tiger that developed a natural, fatal infection in Florida, two female Lone Star ticks (''Amblyomma americanum'') were present on the inguinal skin.
| |
| − |
| |
| − | *Clinically, the disease in cats is characterized by fever, depression, dyspnoea, anorexia, lymphadenopathy, anaemia and icterus leading to death in three to six days
| |
| − |
| |
| − | *Gross findings include pale or icteric mucous membranes, petechiae and ecchymoses in the [[Lungs - Anatomy & Physiology|lung]], [[Heart - Anatomy & Physiology|heart]], [[Lymph Nodes - Anatomy & Physiology|lymph nodes]] and on mucous membranes, splenomegaly, lymphadenomegaly, and hydropericardium
| |
| − |
| |
| − | *Microscopically, numerous large schizonts are present within the cytoplasm of endothelial-associated [[Macrophages - WikiBlood|macrophages]]
| |
| − | **Infected macrophages become markedly enlarged (up to 75μm) and may occlude the lumen of numerous vessels of many tissues, in particular the [[Lungs - Anatomy & Physiology|lungs]]
| |
| − | **Minimal inflammatory reaction is present in tissues
| |
| − |
| |
| − | '''Diagnosis'''
| |
| − | *Merozoites within [[Erythrocytes - WikiBlood|erythrocytes]], best seen on peripheral blood or tissue impressions, are variable in morphology and can occur as round, oval, or signet ring-shaped bodies
| |
| − | **Are 1-5 micrometers in diameter
| |
| − | **Small, peripherally placed basophilic nucleus
| |
| − |
| |
| − | *Organisms that must be distinguished from the intraerythrocytic phase of ''C. felis'' include ''Babesia'' and ''Hemobartonella''
| |
| − | **The blood stage may appear similar to the ring forms of ''Hemobartonella'' and to the piriforms of ''Babesia''
| |
| − | **Unlike ''Cytauxzoon'', ''babesiosis'' and ''hemobartonellosis'' do not have a tissue stage of infection
| |
| − |
| |
| − | *Differential diagnosis for the tissue phase of ''cytauxzoonosis'' includes other small (less than 5 μm), intrahistiocytic organisms such as ''Toxoplasma'', ''Leishmania'' and ''Histoplasma''
| |
| | | | |
| | ==''Theileria''== | | ==''Theileria''== |