Difference between revisions of "Piroplasmida"
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+ | '''[[Babesia|''Babesia'']] | ||
+ | |||
+ | |||
+ | ==''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''== | ||
+ | [[Image:Theileria parva life cycle.jpg|thumb|right|150px|''Theileria parva'' Life Cycle Diagram - Dennis Jacobs & Mark Fox RVC]] | ||
+ | [[Image:Lymph node smear East Coast Fever.jpg|thumb|right|150px|Lymph node smear of a cow with East Coast Fever - Drs. Elizabeth Howerth and Bruce LeRoy, Department of Pathology, UGA College of Veterinary Medicine]] | ||
+ | [[Image:H and E stain brain East Coast Fever.jpg|thumb|right|150px|H and E stain of brain and meningal vessels of a cow with East Coast Fever - Drs. Elizabeth Howerth and Bruce LeRoy, Department of Pathology, UGA College of Veterinary Medicine]] | ||
+ | [[Image:Theileria cervi.jpg|thumb|right|150px|''Theileria cervi'' (deer) - Drs. Elizabeth Howerth and Bruce LeRoy, Department of Pathology, UGA College of Veterinary Medicine]] | ||
+ | *Main species of veterinary importance is ''Theileria parva'' | ||
+ | **Causes '''East Coast Fever''' | ||
+ | ***Severe, proliferative lymphatic disease of cattle | ||
+ | ***Central and Eastern Africa | ||
+ | ***Transmitted by [[Hard Ticks - Overseas|''Rhipicephalus appendiculatus'']] | ||
+ | ***[[Ticks#Disease Transmission|Trans-stadial]] transmission | ||
+ | |||
+ | *Other ''Theileria'' species cause production losses in cattle and sheep in the Middle East, Mediterranean and in Northern Africa | ||
+ | |||
+ | '''Life Cycle''' | ||
+ | *Incubation phase lasts 1 week | ||
+ | |||
+ | *Lymphoblast proliferation | ||
+ | **Local [[Lymph Nodes - Anatomy & Physiology|lymph node]] first infected then spreads through body | ||
+ | **Occurs in week two | ||
+ | |||
+ | *Lymphoid depletion | ||
+ | **[[Lymphocytes - WikiBlood|Lymphocytes]] killed | ||
+ | **Decreases lymphopoiesis | ||
+ | **Occurs in week 3 | ||
+ | |||
+ | *Total incubation period takes about 18 days | ||
+ | |||
+ | '''Diagnosis''' | ||
+ | *Clinical signs | ||
+ | **Pyrexia | ||
+ | **Enlarged local [[Lymph Nodes - Anatomy & Physiology|lymph node]] | ||
+ | ***Usually parotid [[Lymph Nodes - Anatomy & Physiology|lymph node]] as [[Hard Ticks - Overseas|''Rhipicephalus appendiculatus'']] feeds in the ear | ||
+ | **Loss of condition | ||
+ | |||
+ | *Examine Giemsa stained smears of: | ||
+ | **Local [[Lymph Nodes - Anatomy & Physiology|lymph node]] aspirated for schizonts | ||
+ | **Blood smears for piroplasms in red blood cells | ||
+ | |||
+ | *Post-mortem | ||
+ | **Pulmonary oedema | ||
+ | **Gut mucosal haemorrhages | ||
+ | **[[Lymph Nodes - Anatomy & Physiology|Lymph node]] and [[Spleen - Anatomy & Physiology|splenic]] cellular atrophy | ||
+ | |||
+ | '''Control''' | ||
+ | *Integrated control of both the [[Tick Control|tick vector]] and disease | ||
+ | **[[Vaccines - WikiBlood|Vaccination]] and [[Ectoparasiticides]] | ||
+ | |||
+ | *Current [[Vaccines - WikiBlood|vaccination]] is live unattentuated | ||
+ | **Contains frozen stabilate of ground up tick gut containing infective sporozoites | ||
+ | **Long lasting oxytetracycline administered at the same time to slow down schizogony giving the immune response time to develop | ||
+ | |||
+ | ==[[Protozoa Flashcards - Wikibugs#Piroplasmida|Piroplasmida Flashcards]]== |
Revision as of 22:18, 9 April 2010
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
- In Theileria the exoerythrocytic stage occurs primarily within 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 one to three days before they are observed in erythrocytes
Pathogenicity
- 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 lung, heart, lymph nodes and on mucous membranes, splenomegaly, lymphadenomegaly, and hydropericardium
- Microscopically, numerous large schizonts are present within the cytoplasm of endothelial-associated macrophages
- Infected macrophages become markedly enlarged (up to 75μm) and may occlude the lumen of numerous vessels of many tissues, in particular the lungs
- Minimal inflammatory reaction is present in tissues
Diagnosis
- Merozoites within 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
- Main species of veterinary importance is Theileria parva
- Causes East Coast Fever
- Severe, proliferative lymphatic disease of cattle
- Central and Eastern Africa
- Transmitted by Rhipicephalus appendiculatus
- Trans-stadial transmission
- Causes East Coast Fever
- Other Theileria species cause production losses in cattle and sheep in the Middle East, Mediterranean and in Northern Africa
Life Cycle
- Incubation phase lasts 1 week
- Lymphoblast proliferation
- Local lymph node first infected then spreads through body
- Occurs in week two
- Lymphoid depletion
- Lymphocytes killed
- Decreases lymphopoiesis
- Occurs in week 3
- Total incubation period takes about 18 days
Diagnosis
- Clinical signs
- Pyrexia
- Enlarged local lymph node
- Usually parotid lymph node as Rhipicephalus appendiculatus feeds in the ear
- Loss of condition
- Examine Giemsa stained smears of:
- Local lymph node aspirated for schizonts
- Blood smears for piroplasms in red blood cells
- Post-mortem
- Pulmonary oedema
- Gut mucosal haemorrhages
- Lymph node and splenic cellular atrophy
Control
- Integrated control of both the tick vector and disease
- Current vaccination is live unattentuated
- Contains frozen stabilate of ground up tick gut containing infective sporozoites
- Long lasting oxytetracycline administered at the same time to slow down schizogony giving the immune response time to develop