Difference between revisions of "Coccidia"

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[[Coccidiosis]]
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#REDIRECT[[:Category:Coccidia]]
 
 
==Introduction==
 
 
 
[[Image:Coccidia.jpg|thumb|right|150px|Coccidia - Joel Mills]]
 
 
 
*The '''oocyst''' is the resistant stage in the environment
 
 
 
*The infective '''sporozoite''' is released from the oocyst
 
 
 
*Inside the host, the sporozoites invade the intestinal epithelial tissue
 
**Sporozoites feed and grow
 
 
 
*As the sporozoite grows the nucleus divides forming a '''schizont'''
 
 
 
*The schizont contains numerous elongated '''merozoites'''
 
 
 
*The formation of merozoites is the first asexual reproductive stage called '''schizogony'''
 
 
 
*The schizont ruptures releasing the merozoites which also invade the epithelial cells
 
 
 
*Another generation of schizonts form which is the beginning of the sexual phase of reproduction called '''gametogony'''
 
 
 
*The merozoites form male '''microgamonts''' or female '''macrogamonts'''
 
**Collectively known as gamonts or gametocytes
 
 
 
*The microgamonts released from the microgametocyte penetrate and fertilise the macrogamont (which is contained within the macrogametocyte)
 
 
 
*Gametogony forms the '''zygote'''
 
**Surrounded by a cyst wall
 
**Forms the '''oocyst'''
 
 
 
*The oocyst is passed in the faeces and is unsporulated
 
 
 
*The oocyst becomes sporulated in the second asexual reproductive phase called '''sporogony'''
 
 
 
*Once the oocyst is sporulated it is infective
 
[[Eimeria spp.|''Eimeria'' spp.]]
 
 
 
 
 
[[Isospora spp.|''Isospora'' spp.]]
 
 
 
 
 
[[Coccidia - Poultry]]
 
 
 
[[Coccidiosis - Poultry]]
 
 
 
 
 
==Other Avian Coccidia==
 
===Coccidia of Turkeys===
 
 
 
*5 ''Eimeria'' species
 
**2 important pathogenically
 
 
 
*''Eimeria'' in [[Caecum - Anatomy & Physiology|caeca]] causes petechial haemorrhages and caseous [[Caecum - Anatomy & Physiology|caecal]] cores
 
 
 
*''Eimeria'' in the anterior and mid-intestine causes necrotic enteritis and petechial haemorrhages
 
 
 
*Causes watery [[Intestine Diarrhoea - Pathology|diarrhoea]] in young poults and some mortality
 
 
 
===Coccidia of Geese===
 
*3 ''Eimeria'' species
 
 
 
*2 intestinal species causing macroscopic lesions in [[Urinary System - Anatomy & Physiology#The Kidney|kidney tubules]]
 
**Oocysts carried in urine and pass out with faeces
 
 
 
*Renal species cause severe disease in goslings
 
**Depression, emaciation, [[Intestine Diarrhoea - Pathology|diarrhoea]] and sometimes death
 
 
 
===Coccidia of Ducks===
 
[[Image:Crested duck.jpg|thumb|right|150px|Crested duck - nabrown RVC]]
 
*Several ''Eimeria'' species
 
 
 
*Another coccidia species which produces 8 sporozoites but these are not enclosed in a sporocyst
 
 
 
*Causes severe enteritis and mortality in ducklings
 
**Haemorrhages and pale  focal lesions in [[Small Intestine - Anatomy & Physiology|small intestine]]
 
 
 
===Coccidia of Game Birds===
 
*3 main species
 
 
 
*[[Caecum - Anatomy & Physiology|Caecal]] species most pathogenic causing white [[Caecum - Anatomy & Physiology|caecal]] cores
 
 
 
==Coccidia of Cattle==
 
[[Image:Coccidia ruminant.jpg|thumb|right|150px|''Eimeria'' sp. of ruminants - Joaquim Castellà Veterinary Parasitology Universitat Autònoma de Barcelona]]
 
[[Image:Coccidia oocyst ruminant.jpg|thumb|right|150px|Coccidia oocyst from ruminant faeces - Joaquim Castellà Veterinary Parasitology Universitat Autònoma de Barcelona]]
 
*Many species affect cattle
 
 
 
*Cattle under a year old are usually infected sporadically
 
 
 
*2-3 week prepatent period
 
 
 
*''Eimeria bovis''
 
**Endogenous stages in central lacteal of villi and epithelial cells of [[Caecum - Anatomy & Physiology|caecum]] and [[Colon - Anatomy & Physiology|colon]]
 
**Causes [[Intestine Diarrhoea - Pathology|diarrhoea]] and enteritis
 
**Oocysts are 28x20μm
 
**Moderately pathogenic
 
 
 
*''Eimeria zuernii''
 
**Endogenous stages in connective tissue of lamina propria of the lower [[Small Intestine - Anatomy & Physiology|small intestine]] and in the epithelial cells of the [[Caecum - Anatomy & Physiology|caecum]] and [[Colon - Anatomy & Physiology|colon]]
 
**More pathogenic than ''Eimeria bovis''
 
**Causes blood stained dysentery, tenesmus and sloughed mucosa
 
**Oocysts are spherical and measure 16μm
 
 
 
*Mainly occurs in calves in poor conditions and bought-in calves
 
**Also occurs in suckler calves turned out in spring
 
 
 
*''Eimeria alabamensis'' associated with [[Intestine Diarrhoea - Pathology|diarrhoea]] in calves after spring turnout
 
 
 
*[[Materno-fetal immunity - WikiBlood#Passive transfer via colostrum|Passive immunity]] is sufficient during the neonatal period
 
 
 
*Can be concurrent with cryptosporidium, viral and bacterial agents
 
 
 
'''Diagnosis'''
 
*History, clinical signs, [[Intestine Diarrhoea - Pathology|diarrhoea]] (often with blood) and a decrease in weight gain
 
 
 
*Post-mortem
 
**Diffuse inflammation and thickening of [[Caecum - Anatomy & Physiology|caecal]] mucosa (and sometimes [[Ileum - Anatomy & Physiology|ileal]] and [[Colon - Anatomy & Physiology|colonic]] mucosa)
 
**Masses of gamonts and oocysts in scrapings
 
 
 
*High faecal oocyst count
 
**However, healthy animals can pass millions of oocysts from mixed species infections which have no pathogenic significance
 
**Animals may die before oocysts are shed
 
 
 
'''Control'''
 
*Improve husbandry
 
**Improve sanitation
 
**Increase bedding
 
**Raise food and water troughs to avoid faecal contamination
 
 
 
*Preventative in-feed medication
 
**E.g. Decoquinate
 
 
 
*Injectable antiprotozoals may limit oocyst production but animals should still be moved to a clean environment
 
**E.g. Sulphamethoxypyridazine
 
 
 
==Coccidia of Sheep==
 
[[Image:Isospora felis sporulated.jpg|thumb|right|150px|''Isospora felis'' sporulated - Courtesy of the Laboratory of Parasitology, University of Pennsylvania School of Veterinary Medicine]]
 
[[Image:Isospora felis unsporulated.jpg|thumb|right|150px|''Isospora felis'' unsporulated - Courtesy of the Laboratory of Parasitology, University of Pennsylvania School of Veterinary Medicine]]
 
*11 different Coccidia species although only two are of clinical significance
 
**Giant schizonts visible as white spots
 
 
 
*''Eimeria ovinoidalis''
 
**Highly pathogenic
 
**[[Intestine Diarrhoea - Pathology|Diarrhoea]]
 
**Parasitises the [[Caecum - Anatomy & Physiology|caecum]] and [[Colon - Anatomy & Physiology|colon]]
 
 
 
*''Eimeria crandalis''
 
**Varying pathogenicity
 
**Scours, grey, foul-smelling faeces
 
**Parasitises the [[Small Intestine - Anatomy & Physiology|small intestine]], [[Caecum - Anatomy & Physiology|caecum]] and [[Colon - Anatomy & Physiology|colon]]
 
 
 
*2 week prepatent period
 
 
 
*Disease frequently seen in lambs under 6 months old
 
**More often in twins and triplets when single lambs
 
 
 
*Oocyts from ewes (immune carriers) accumulate in poorly managed litter or around feed and water troughs
 
 
 
*Lambs born early in the year amplify the parasite problem increasing the parasite risk to lambs born later in the year
 
 
 
*Affected lambs may die before oocysts are found in the faeces
 
**Post-mortem diagnosis difficult
 
 
 
*Different species of ''Eimeria'' occurs in sheep and goats
 
 
 
*Infection may be coincident with ''Neospora'' or ''Cryptosporidium'' infections
 
**Mixed infections complicate the diagnosis as oocyst differentiation is difficult
 
 
 
*Other non-pathogenic species can cause papillomatous mucosal growths
 
 
 
'''Control'''
 
*Improve husbandry
 
**Avoid overcrowding
 
**Decrease stress
 
 
 
*Improve hygiene by dagging ewes
 
 
 
*Avoid mixing lambs of different ages
 
 
 
*Preventative measures include creep feeding lambs with decoquinate or oral dosing with diclazuril when lambs are 4-6 weeks
 
**A second dose can be given after 3 weeks
 
 
 
==Coccidia of Goats==
 
[[Image:Goats.jpg|thumb|right|150px|Goats - nabrown RVC]]
 
[[Image:Eimeria leukarti horse.jpg|thumb|right|150px|''Eimeria leukarti'' - Joaquim Castellà Veterinary Parasitology Universitat Autònoma de Barcelona]]
 
[[Image:Isospora suis oocyst.jpg|thumb|right|150px|''Isospora suis'' oocyst from pig faeces - Joaquim Castellà Veterinary Parasitology Universitat Autònoma de Barcelona]]
 
[[Image:Isospora canis.jpg|thumb|right|150px|''Isospora canis'' - Joaquim Castellà Veterinary Parasitology Universitat Autònoma de Barcelona]]
 
[[Image:Coccidia.jpg|thumb|right|150px|Coccidia in Cat Faeces - Joel Mills]]
 
[[Image:Isospora felis.jpg|thumb|right|150px|''Isospora felis'' - Joaquim Castellà Veterinary Parasitology Universitat Autònoma de Barcelona]]
 
*Many ''Eimeria'' species
 
 
 
*2 ''Eimeria'' are pathogenic
 
**Cause [[Intestine Diarrhoea - Pathology|diarrhoea]] and a decreased growth rate
 
 
 
*Different species of ''Eimeria'' occurs in sheep and goats
 
 
 
==Coccidia of Horses==
 
 
 
*Only one atypical ''Eimeria''
 
 
 
*Forms large subepithelial gametocytes in villi
 
 
 
*Large, dark coloured oocysts
 
**Approximately 12μm
 
 
 
*Occasionally causes [[Intestine Diarrhoea - Pathology|diarrhoea]]
 
 
 
*''Besnoitia bennetti'' in [[Respiratory Parasitic Infections - Pathology#Besnoitia bennetti|larynx]] of horses
 
 
 
==Coccidia of Pigs==
 
*Many species of ''Eimeria'' and ''Isospora''
 
 
 
*Only ''Isospora suis'' is of clinical pathogenic importance
 
 
 
*Causes sporadic, serious and sometimes fatal disease in unweaned piglets
 
**Causes profuse [[Intestine Diarrhoea - Pathology|diarrhoea]]
 
 
 
*Very short 1 week prepatent period
 
 
 
*[[Intestine Diarrhoea - Pathology|Diarrhoea]] starts before oocysts are shed in faeces
 
**Ante-mortem diagnosis is difficult
 
 
 
*Death usually occurs after parasites have left the host
 
**Post-mortem diagnosis difficult
 
**''Isospora'' infections are '''self-limiting'''
 
 
 
==Coccidia of Dogs==
 
*2 common and 2 less common ''Isospora'' species
 
 
 
*Occasionally can cause disease
 
 
 
*Little pathogenicity
 
 
 
*Even if faecal oocyst count is high, other causes of [[Intestine Diarrhoea - Pathology|diarrhoea]] should be looked for
 
 
 
*''Hepatozoon americanum'' and subclinical ''H. canis'' in [[Bones Hyperplastic and Neoplastic - Pathology#Hepatozoon|periosteal bone formation]]
 
**Both are Tick borne diseases
 
***''H. canis'' – ''Rhipicephalus sanguineus''
 
***Ticks become infected by ingesting a blood meal containing macrophages and [[Neutrophils - WikiBlood|neutrophils]] infected with the parasite gamonts -> sexual replication in the gut of the tick -> oocysts containing infective sporozoites -> dogs ingest the tick  schizogony occurs in numerous tissues
 
 
 
==Coccidia of Cats==
 
*2 common ''Isospora'' species with little clinical significance
 
 
 
*Oocysts in faeces have to be distinguised from those of ''Toxoplasma'' (smaller) and ''Sarcocytis'' (sporulated or naked sporocyts in faeces)
 
 
 
==Coccidia of Rabbits==
 
*3 pathogenic ''Eimeria'' species
 
**2 in the [[Caecum - Anatomy & Physiology|caecum]]
 
**1 in the bile duct
 
 
 
*''Eimeria steidae''
 
**Parasitises the bile duct epithelium
 
**Travels via the bile duct to the [[Liver - Anatomy & Physiology|liver]] where it forms large white nodules
 
**Oocysts travel in the bile and are passed out in the faeces
 
**Causes ascites, [[Intestine Diarrhoea - Pathology|diarrhoea]], weight loss and polyuria
 
 
 
*Serious disease of both pet and farmed rabbits
 
 
 
*Treatment is by administration of drugs in drinking water
 
**E.g. Toltrazuril
 
 
 
*Hygiene is the best method of prevention to prevent sporocysts from sporulating
 
 
 
*Medicated feed can be used in commercial units
 
**E.g. Rabenidine
 
 
 
==[[Protozoa Flashcards - Wikibugs#Coccidia|Coccidia Flashcards]]==
 
[[Category:Coccidia]]
 

Latest revision as of 16:48, 20 May 2010

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