Tissue cyst-forming coccidia - Revision history

Bara: Redirected page to Category:Tissue Cyst Forming Coccidia

2010-04-09T23:31:52Z

Redirected page to Category:Tissue Cyst Forming Coccidia

Bara at 23:14, 9 April 2010

2010-04-09T23:14:58Z

Bara: Replaced content with 'Neospora Sarcocystis Toxoplasma ==Tissue Cyst Forming Coccidia Flashcards=='

2010-04-09T23:03:04Z

Replaced content with 'Neospora Sarcocystis Toxoplasma ==Tissue Cyst Forming Coccidia Flashcards=='

Bara at 22:59, 9 April 2010

2010-04-09T22:59:07Z

Bara at 22:40, 9 April 2010

2010-04-09T22:40:58Z

Nabrown at 17:33, 7 January 2009

2009-01-07T17:33:54Z

Nabrown at 15:41, 7 January 2009

2009-01-07T15:41:31Z

Rmeikle at 10:54, 7 January 2009

2009-01-07T10:54:53Z

Show changes

Nabrown: /* Sarcocystis */

2008-12-21T14:57:43Z

Sarcocystis

Nabrown: /* Toxoplasma */

2008-12-21T14:56:32Z

Toxoplasma

← Older revision		Revision as of 23:31, 9 April 2010
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−	[[~~Neospora]]~~	+	#REDIRECT[[:Category:Tissue Cyst Forming Coccidia]]
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−	~~[[Sarcocystis]]~~
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−	~~[[Toxoplasma]]~~
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−	[[Tissue Cyst Forming Coccidia ~~Flashcards~~]]

← Older revision		Revision as of 23:14, 9 April 2010
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−	==[[~~Protozoa Flashcards - Wikibugs#Tissue Cyst Forming Coccidia\|~~Tissue Cyst Forming Coccidia Flashcards]]==	+	[[Tissue Cyst Forming Coccidia Flashcards]]

← Older revision		Revision as of 23:03, 9 April 2010
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−	~~==Toxoplasma==~~	+	[[Toxoplasma]]
−	~~[[Image:Toxoplasma gondii.jpg\|thumb\|right\|150px\|''Toxoplasma gondii'' - Ke Hu and John Murray]]~~
−	[[~~Image:Toxoplasma sporulated oocyst.jpg\|thumb\|right\|150px\|''~~Toxoplasma~~'' Sporulated Oocyst - Wikimedia Commons~~]]
−	~~[[Image:Toxoplasma Tacchyzoites.jpg\|thumb\|right\|150px\|''Toxoplasma'' Tacchyzoites - Wikimedia Commons]]~~
−	~~[[Image:Toxoplasma Life Cycle.jpg\|thumb\|right\|150px\|''Toxoplasma'' Life Cycle Diagram - Dennis Jacobs & Mark Fox RVC]]~~
−	~~[[Image:Toxoplasma gondii 2.jpg\|thumb\|right\|150px\|''Toxoplasma gondii'' - Courtesy of the Laboratory of Parasitology, University of Pennsylvania School of Veterinary Medicine]]~~
−	*Major pathogenic species called ''Toxoplasma gondii''

−	*Causes disease in a wide range of animal species including humans
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−	*Important cause of abortion in sheep
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−	*Zoonotic
−	**Can cause abortion
−	**Can cause congenitally aquired defects
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−	*Forms a sporulated oocyst which is only 10μm
−	**Contains 2 sporocysts with 4 sporozoites
−
−	*Transmission through ingesting the intermediate host or via the faecal-oral route
−
−	~~'''Life Cycle'''~~
−	*Complex
−
−	*Usually indirect
−	**Referred to as '''facultatively heteroxenous'''
−	**Intermediate host is not essential for completion of the life cycle
−
−	*Gametogony (sexual stage) is host specific for felids
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−	*Any warm blooded animal can act as a facultative intermediate host
−	**Asexual reproduction occurs in the intermediate host forming tissue cysts
−	**Intermediate host swallows sporulated oocysts or tissue cysts
−	**Can be transferred between intermediate hosts by carnivorism
−
−	*Cats
−	**Sporulation occurs in 2-3 days
−	**Cats either swallow infective (sporulated) oocysts where ''Toxoplasma gondii'' has a prepatent period of 3 weeks
−	**Or eat the tissues of an infected intermediate host where ''Toxoplasma gondii'' has a prepatent period of 3-10 days
−	**Self-limiting infection
−	**Oocysts are shed for 1-2 weeks
−	***Shedding can occur later if immunity wanes or cat is immuno-compromised
−
−	*Intermediate host
−	**3 sources of infection
−	***Oocysts from environment contaminated by cat faeces
−	***Eating cysts in tissues of other infected hosts through carnivorism or undercooked meat
−	***Transplacental transmission in some host species during the acute phase of infection
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−	*Acute phase of infection
−	**After infection of the intermediate host the organism undergoes a phase of rapid division and dissemination throughout the body
−	***Parasite enters cell and asexual reproduction occurs by '''endodyogeny''' (budding) producing 8-16 '''tachyzoites'''
−	***Tachyzoites are released when host cell bursts
−	***Haematogenous spread as more cells are infected
−	***Infection continues until the animal develops immunity (around 2 weeks) at which point the infection enters the chronic phase
−
−	*Chronic phase of infection
−	**Occurs once the host's immune response has become effective
−	***Groups of slow growing intracellular '''bradyzoites''' become walled off forming infective '''cysts'''
−	***Bradyzoites inside cysts are protected from the host immune response whereas extracellular tachyzoites are killed
−	***Cysts remain viable for months to years and are particularly numerous in muscle and nervous tissue
−	***If immunity is suppressed the infection can revert to the acute form
−
−	~~'''Pathogenesis'''~~
−	*Cat
−	**In the intestinal phase of infection only the superficial cells at the tips of the villi are affected
−	**Little significant pathogenicity
−
−	*Sheep
−	**Mostly asymptomatic
−	**However, if a non-immune ewe is infected during pregnancy the consequences will be serious
−	***Infection during the first trimester leads to resorption
−	**Infection during the second trimester leads to foetal death and mummification
−	**Infection during the last trimester leads to a weak or stillborn lamb
−	**Aborted ewes show focal necrotic placentitis with white lesions in the cotyledons and foetal tissue
−	**Diagnosis is confirmed by Giemsa and serology of the ewe's blood
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−	*Clinical outbreaks of toxoplasmosis are '''sporadic'''
−	**Immunity is acquired before tupping
−	**Significant ill-effects are unlikely if immune ewes are infected during pregnancy
−	**Not shed from sheep to sheep so predicting outbreaks is difficult
−
−	*Humans
−	**Mostly asymptomatic
−	**Virulent strains cause flu-like symptoms, malaise and/or lymphadenopathy
−	**In immunodeficient patients, disease can even be caused by avirulent strains
−	**If a non-immune women is infected during pregnancy, abortion or the birth of a congenitally infected child can result
−	***E.g. Hydrocephalus, opthalmitis, mental retardation
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−	*Dogs
−	**Complication of canine distemper
−	**Causes [[Respiratory Parasitic Infections - Pathology#Toxoplasmosis\|pneumonia]] and encephalitis
−
−	*Cattle and horses
−	**Sometimes infectious causing opthalmitis
−
−	*Toxoplasma can cause [[Pancreas Inflammatory - Pathology#Acute haemorrhagic pancreatitis\|acute interstitial pancreatitis]] in systemic toxoplasmosis
−
−	*''Toxoplasma gondii'' causes [[Muscles Inflammatory - Pathology#Protozoa\|myositis]]
−
−	~~'''Epidemiology'''~~
−	*Serology
−	**Sabin-Feldman Dye test (old method)
−	**ELISA
−	**Mouse inoculation for confirmation
−
−	*Cat
−	**30-80% test seropositive
−	**Each cat sheds oocysts for 1-2 weeks of its life
−
−	*Human
−	**30% seropositive in UK, 70% seropositive in France
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−	*Meat animals
−	**Significant proportion of cattle, sheep, pigs and rabbits can tissue cysts
−
−	~~'''Prevention'''~~
−	*Cat
−	**Impossible if cat is allowed outdoors due to hunting
−	**If kept indoors, only canned food should be fed and vermin controlled
−	**ELISA to check if seropositive
−
−	*Human
−	**Avoid oocyst ingestion
−	***Wash potentially contaminated raw food thoroughly
−	***Wash hands after gardening or handling cats and especially before eating
−	***Clean out cat litter trays every day before oocysts sporulate
−	**Avoid ingestion of tissue cysts
−	***Do not eat undercooked meat
−	***Wash hands after handling raw meat
−	***Take care when lambing or dealing with sheep abortions and stillbirths
−	***Pregnant women should avoid lambing altogether
−
−	*Sheep
−	**Toxovax vaccine
−	***Live, avirulent strain of ''Toxoplasma''
−	***Does not form bradyzoites or tissue cysts
−	***Killed by host immune system
−	***Single dose given 6 weeks before tupping
−	***Protects for 2 years
−	***Immunity boosted by natural challenge
−	**Medicated feed can be given daily during the main risk period
−	***14 weeks before lambing
−	**The best method of protection is to prevent cats from contaminating the pasture, lambing sheds and feed stores

	==[[Protozoa Flashcards - Wikibugs#Tissue Cyst Forming Coccidia\|Tissue Cyst Forming Coccidia Flashcards]]==		==[[Protozoa Flashcards - Wikibugs#Tissue Cyst Forming Coccidia\|Tissue Cyst Forming Coccidia Flashcards]]==

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 [[Neospora]]
-==Sarcocystis==
+[[Sarcocystis]]
 ==Toxoplasma==
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 ==[[Protozoa Flashcards - Wikibugs#Tissue Cyst Forming Coccidia|Tissue Cyst Forming Coccidia Flashcards]]==

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-{{toplink
+[[Neospora]]
 ==Sarcocystis==
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 ==[[Protozoa Flashcards - Wikibugs#Tissue Cyst Forming Coccidia|Tissue Cyst Forming Coccidia Flashcards]]==

← Older revision		Revision as of 17:33, 7 January 2009
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	**The best method of protection is to prevent cats from contaminating the pasture, lambing sheds and feed stores		**The best method of protection is to prevent cats from contaminating the pasture, lambing sheds and feed stores

−	==[[Protozoa Flashcards - Wikibugs\|~~Protozoa~~ Flashcards]]==	+	==[[Protozoa Flashcards - Wikibugs#Tissue Cyst Forming Coccidia\|Tissue Cyst Forming Coccidia Flashcards]]==

← Older revision		Revision as of 15:41, 7 January 2009
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	***14 weeks before lambing		***14 weeks before lambing
	**The best method of protection is to prevent cats from contaminating the pasture, lambing sheds and feed stores		**The best method of protection is to prevent cats from contaminating the pasture, lambing sheds and feed stores
		+
		+	==[[Protozoa Flashcards - Wikibugs\|Protozoa Flashcards]]==

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 [[Image:Sarcocystis in sheep oesophagus.jpg|thumb|right|150px|''Sarcocystis'' in sheep oesophagus - Adam Cuerden]]
 [[Image:Equine protozoal myeloencephalitis.jpg|thumb|right|150px|Equine protozoal myeloencephalitis - Wikimedia Commons]]
 *Most infections are asymptomatic

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 [[Image:Toxoplasma Tacchyzoites.jpg|thumb|right|150px|''Toxoplasma'' Tacchyzoites - Wikimedia Commons]]
 [[Image:Toxoplasma Life Cycle.jpg|thumb|right|150px|''Toxoplasma'' Life Cycle Diagram - Dennis Jacobs & Mark Fox RVC]]
 *1 major pathogenic species called ''Toxoplasma gondii''