Difference between revisions of "Piroplasmida"

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#REDIRECT[[:Category:Piroplasmida]]
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|subtext1=PROTOZOA
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==''Babesia''==
 +
[[Image:Babesia Life Cycle.jpg|thumb|right|150px|''Babesia'' Life Cycle Diagram - Dennis Jacobs & Mark Fox RVC]]
 +
[[Image:Alternative Babesia life cycle diagram.jpg|thumb|right|150px|''Babesia'' Life Cycle - Mariana Ruiz Villarreal]]
 +
*Infects a wide range of host species in different areas of the world
 +
 
 +
*Babesiosis has severe effects on cattle production in parts of the world
 +
**Prevents European breeds from being successful in tropical regions where [[Ticks|ticks]] are endemic.
 +
**Occurs sporadically in the UK and Ireland causing losses of around £8 million per year
 +
 
 +
'''Life Cycle'''
 +
*Both [[Ticks#Disease Transmission|trans-stadial]] and [[Ticks#Disease Transmission|trans-ovarian]] transmission occurs
 +
 
 +
*Each female [[Ticks|tick]] produces 3000 eggs
 +
 
 +
*The [[Ticks|tick]] is the definitive host
 +
 
 +
*''Babesia'' multiplies in the red blood cells by '''budding'''
 +
**Forms 2-4 daughter cells (species dependent)
 +
**Giemsa blood smears can differentiate between species using 'Difquik' stain
 +
 
 +
*''Babesia'' species are either small or large depending on the size of the daughter cells
 +
 
 +
*Small ''Babesia''
 +
**E.g. ''B. divergens''
 +
**E.g. ''B. gibsoni''
 +
**Peripheral nucleus
 +
**Obtuse angle
 +
 
 +
*Large ''Babesia''
 +
**E.g. ''B. major''
 +
**E.g. ''B. canis-complex''
 +
**Central nucleus
 +
**Acute angle
 +
 
 +
*Daughter cells disrupt the red blood cell and are released
 +
**Spread and infect other red blood cells
 +
 
 +
*Antigen is released which adsorbs onto other red blood cells
 +
**Causes haemolysis and [[Pigmentation and Calcification - Pathology#Haemoglobin|haemoglobin pigmentation]]
 +
**Causes haemolytic anaemia, haemoglobinuria and fever
 +
 
 +
*Cattle
 +
**Sudden onset
 +
**Often fatal if untreated
 +
**Causes 'pipestem' faeces
 +
**Clumping of red blood cells in brain capillaries can occur causing neurological signs
 +
 
 +
'''Epidemiology'''
 +
*Determined by:
 +
**Number of infected [[Ticks|ticks]] seeking a blood meal ('''tick pressure''')
 +
**Calves under 9 months are refractory to disease
 +
***Can develop immunity if exposed without showing clinical signs
 +
**'Premunity' (a good protective immunity) develops quickly in infected cattle causing a 'carrier state'
 +
**Immunity can wane in the absence of re-infection
 +
**Uninfected cattle remain susceptible
 +
 
 +
*Predisposing factors:
 +
**Susceptible animals introduced into an infected area
 +
**Infected [[Ticks|ticks]] introduced into a clean area
 +
**Infected cattle introduced into an area with clean [[Ticks|ticks]]
 +
**Temporary reduction in the [[Ticks|tick]] population decreasing the transmission rate (causing enzootic instability)
 +
**Infected are transported or stressed in other ways, e.g. parturition
 +
 
 +
*In the UK
 +
**Sporadic disease
 +
**Enzootic instability
 +
**Occurs mostly during the spring and autumn during periods of greatest [[Ticks|tick]] activity
 +
**Occurs mostly in stressed cattle under 2 years old on rough grazing
 +
**''B. divergens'' the most common species
 +
**[[Hard Ticks - UK#Ixodes spp.|''Ixodes ricinus'']] is the vector
 +
**[[Ticks#Disease Transmission|Trans-ovarial]] transmission to the next generation occurs
 +
**''B. major'' occurs in South East England but is not pathogenic
 +
***Vector is [[Hard Ticks - UK#Important Hard Ticks|''Haemaphysalis'']]
 +
 
 +
*Overseas
 +
**''B. bovis'' causes considerable losses in cattle in many tropical and sub-tropical areas
 +
***In Australia an attenuated vaccine is used
 +
***Vector is [[Hard Ticks - Overseas|''Boophilus'']]
 +
**''B. bigemina'' causes problems in Africa and South America
 +
***Vector is [[Hard Ticks - Overseas|''Boophilus'']]
 +
 
 +
*Dogs
 +
**Complex epidemiology
 +
**Recognised species are extending their endemic ranges due to the discovery of the small ''Babesia'' species, pet passport scheme and increased overseas travel
 +
**Large species comprises 3 subspecies
 +
***''B. canis canis'' is the most important
 +
****[[Hard Ticks - Overseas|''Dermacentor'']] vector
 +
****Largely confined to southern Europe but is spreading
 +
***''B. canis'' uses [[Hard Ticks - Overseas|''Rhipicephalus'']] as a vector and is spreading northwards through Europe
 +
***''B. gibsoni'' is now established in the USA and South-East Asia
 +
**British dogs have no immunity as no species are endemic to the UK so are highly susceptible if taken abroad
 +
**Prevention of [[Ticks|tick]] bites by use of an 'Amitraz' collar is currently the best method of protection
 +
 
 +
*Horses
 +
**2 species occur
 +
**''B. equi'' is the most pathogenic
 +
**Not endemic to the UK
 +
**Serology using ELISA or IFAT to diagnose
 +
 
 +
*Sheep and goats
 +
**Several species
 +
**Little clinical significance
 +
 
 +
===Enzootic Instability===
 +
*Low rate of transmission
 +
 
 +
*Few infected [[Ticks|ticks]]
 +
 
 +
*Infrequent exposure
 +
 
 +
*Immunity wanes or is completely absent in many individuals
 +
 
 +
*Low levels of herd immunity
 +
 
 +
*'''Higher''' incidence of disease
 +
 
 +
===Enzootic Stability===
 +
*High rate of transmission
 +
 
 +
*Many infected ticks
 +
 
 +
*Frequent exposure boosts immunity
 +
 
 +
*High level of herd immunity
 +
 
 +
*'''Lower''' incidence of disease
 +
 
 +
==''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 22:16, 9 April 2010


Infectious agents and parasitesWikiBugs Banner.png
PARASITES
PROTOZOA



Babesia

Babesia Life Cycle Diagram - Dennis Jacobs & Mark Fox RVC
Babesia Life Cycle - Mariana Ruiz Villarreal
  • Infects a wide range of host species in different areas of the world
  • Babesiosis has severe effects on cattle production in parts of the world
    • Prevents European breeds from being successful in tropical regions where ticks are endemic.
    • Occurs sporadically in the UK and Ireland causing losses of around £8 million per year

Life Cycle

  • Each female tick produces 3000 eggs
  • The tick is the definitive host
  • Babesia multiplies in the red blood cells by budding
    • Forms 2-4 daughter cells (species dependent)
    • Giemsa blood smears can differentiate between species using 'Difquik' stain
  • Babesia species are either small or large depending on the size of the daughter cells
  • Small Babesia
    • E.g. B. divergens
    • E.g. B. gibsoni
    • Peripheral nucleus
    • Obtuse angle
  • Large Babesia
    • E.g. B. major
    • E.g. B. canis-complex
    • Central nucleus
    • Acute angle
  • Daughter cells disrupt the red blood cell and are released
    • Spread and infect other red blood cells
  • Antigen is released which adsorbs onto other red blood cells
  • Cattle
    • Sudden onset
    • Often fatal if untreated
    • Causes 'pipestem' faeces
    • Clumping of red blood cells in brain capillaries can occur causing neurological signs

Epidemiology

  • Determined by:
    • Number of infected ticks seeking a blood meal (tick pressure)
    • Calves under 9 months are refractory to disease
      • Can develop immunity if exposed without showing clinical signs
    • 'Premunity' (a good protective immunity) develops quickly in infected cattle causing a 'carrier state'
    • Immunity can wane in the absence of re-infection
    • Uninfected cattle remain susceptible
  • Predisposing factors:
    • Susceptible animals introduced into an infected area
    • Infected ticks introduced into a clean area
    • Infected cattle introduced into an area with clean ticks
    • Temporary reduction in the tick population decreasing the transmission rate (causing enzootic instability)
    • Infected are transported or stressed in other ways, e.g. parturition
  • In the UK
    • Sporadic disease
    • Enzootic instability
    • Occurs mostly during the spring and autumn during periods of greatest tick activity
    • Occurs mostly in stressed cattle under 2 years old on rough grazing
    • B. divergens the most common species
    • Ixodes ricinus is the vector
    • Trans-ovarial transmission to the next generation occurs
    • B. major occurs in South East England but is not pathogenic
  • Overseas
    • B. bovis causes considerable losses in cattle in many tropical and sub-tropical areas
      • In Australia an attenuated vaccine is used
      • Vector is Boophilus
    • B. bigemina causes problems in Africa and South America
  • Dogs
    • Complex epidemiology
    • Recognised species are extending their endemic ranges due to the discovery of the small Babesia species, pet passport scheme and increased overseas travel
    • Large species comprises 3 subspecies
      • B. canis canis is the most important
        • Dermacentor vector
        • Largely confined to southern Europe but is spreading
      • B. canis uses Rhipicephalus as a vector and is spreading northwards through Europe
      • B. gibsoni is now established in the USA and South-East Asia
    • British dogs have no immunity as no species are endemic to the UK so are highly susceptible if taken abroad
    • Prevention of tick bites by use of an 'Amitraz' collar is currently the best method of protection
  • Horses
    • 2 species occur
    • B. equi is the most pathogenic
    • Not endemic to the UK
    • Serology using ELISA or IFAT to diagnose
  • Sheep and goats
    • Several species
    • Little clinical significance

Enzootic Instability

  • Low rate of transmission
  • Infrequent exposure
  • Immunity wanes or is completely absent in many individuals
  • Low levels of herd immunity
  • Higher incidence of disease

Enzootic Stability

  • High rate of transmission
  • Many infected ticks
  • Frequent exposure boosts immunity
  • High level of herd immunity
  • Lower incidence of disease

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

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

Theileria parva Life Cycle Diagram - Dennis Jacobs & Mark Fox RVC
File:Lymph node smear East Coast Fever.jpg
Lymph node smear of a cow with East Coast Fever - Drs. Elizabeth Howerth and Bruce LeRoy, Department of Pathology, UGA College of Veterinary Medicine
File:H and E stain brain East Coast Fever.jpg
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
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
  • 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

  • Examine Giemsa stained smears of:
    • Local lymph node aspirated for schizonts
    • Blood smears for piroplasms in red blood cells
  • Post-mortem

Control

  • 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

Piroplasmida Flashcards