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[[Image:Toxoplasma gondii.jpg|thumb|right|150px|''Toxoplasma gondii'' <br> Ke Hu and John Murray, WikiMedia Commons]]

[[Image:Toxoplasma gondii.jpg|thumb|right|150px|''Toxoplasma gondii'' <br> Ke Hu and John Murray, WikiMedia Commons]]

[[Image:Toxoplasma Life Cycle.jpg|thumb|right|150px|''Toxoplasma'' Life Cycle Diagram - Dennis Jacobs & Mark Fox RVC]]

[[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]]

[[Image:Toxoplasma gondii 2.jpg|thumb|right|150px|''Toxoplasma gondii'' - Courtesy of the Laboratory of Parasitology, University of Pennsylvania School of Veterinary Medicine]]

 

==Introduction==

==Introduction==

''Toxoplasma gondii'' is an obligate, intracellular coccidian parasite that is capable of infecting most mammals including man. Cats and other Felidae are the definitive host for ''T. gondii'', and all other mammals are intermediate hosts. ''Toxoplasma gondii'' has three infectious stages:  

''Toxoplasma gondii'' is an obligate, intracellular coccidian parasite that is capable of infecting most mammals including man. Cats and other Felidae are the definitive host for ''T. gondii'', and all other mammals are intermediate hosts. ''Toxoplasma gondii'' has three infectious stages:  

==Life Cycle==

==Life Cycle==

The life cycle of ''T. gondii'' is complex, usually indirect and often referred to as '''facultatively heteroxenous'''. Intermediate host is not essential for completion of the life cycle. Gametogony (sexual stage) is host specific for felids.

The life cycle of ''T. gondii'' is cmplex, usually indirect and often referred to as '''facultatively heteroxenous'''. Intermediate host is not essential for completion of the life cycle. Gametogony (sexual stage) is host specific for felids.

===Cats===

===Cats===

As cats generally develop immunity to ''T. gondii'' after the initial infection, they will only shed oocysts once in their lifetime.

As cats generally develop immunity to ''T. gondii'' after the initial infection, they will only shed oocysts once in their lifetime.

 

===Other species===

===Other species===

When other, ‘’’non-feline, carnivores’’’ (such as dogs) or sheep consume tissue cysts or oocysts from cat faeces, ''Toxoplasma gondii'' initiates '''extraintestinal replication'''. This process is the same for all hosts, and does not vary with the form of the parasite ingested. '''Bradyzoites''' and '''sporozoites''', from cysts and oocysts respectively, are released in the intestine and infect the intestinal epithelium where they replicate - asexual reproduction by '''endodyogeny''' (budding) producing 8-16 '''tachyzoites'''. Tachyzoites are lunate in shape, about 6 microns in diameter and possess the ability to multiply in almost any cell type. The infected cell ruptures to release tachyzoites which then disseminate via blood and lymph to infect other tissues. Tachyzoites then replicate intracellularly and, if the cell does not burst, they eventually encyst and persist for the life of the host. Tissue cysts readily form in the CNS, muscles and visceral organs.  

When other, ‘’’non-feline, carnivores’’’ (such as dogs) or sheep consume tissue cysts or oocysts from cat faeces, ''Toxoplasma gondii'' initiates '''extraintestinal replication'''. This process is the same for all hosts, and does not vary with the form of the parasite ingested. '''Bradyzoites''' and '''sporozoites''', from cysts and oocysts respectively, are released in the intestine and infect the intestinal epithelium where they replicate - asexual reproduction by '''endodyogeny''' (budding) producing 8-16 '''tachyzoites'''. Tachyzoites are lunate in shape, about 6 microns in diameter and possess the ability to multiply in almost any cell type. The infected cell ruptures to release tachyzoites which then disseminate via blood and lymph to infect other tissues. Tachyzoites then replicate intracellularly and, if the cell does not burst, they eventually encyst and persist for the life of the host. Tissue cysts readily form in the CNS, muscles and visceral organs.  

==Transmission==

==Transmission==

If a pregnant queen or human is naive to ''Toxoplasma gondii'' at the time of ingestion, '''transplacental infection''' can occur. The outcome of this depends on the stage of gestation. Infection during the first trimester usually has severe consequences, such as stillbirth or abortion; infections during the second or third trimesters are more likely to give rise to an infected foetus.

If a pregnant queen or human is naive to ''Toxoplasma gondii'' at the time of ingestion, '''transplacental infection''' can occur. The outcome of this depends on the stage of gestation. Infection during the first trimester usually has severe consequences, such as stillbirth or abortion; infections during the second or third trimesters are more likely to give rise to an infected foetus.

For more information see:

For more information see:

<big>'''[[Toxoplasmosis - Small Animal|Cat Toxoplasmosis]]

 

<big>'''[[Toxoplasmosis - Cat and Dog|Cat Toxoplasmosis]]

'''[[Toxoplasmosis - Sheep|Sheep Toxoplasmosis]]

'''[[Toxoplasmosis - Sheep|Sheep Toxoplasmosis]]

'''[[Toxoplasmosis - Human|Human Toxoplasmosis]]</big>

'''[[Toxoplasmosis - Human|Human Toxoplasmosis]]</big>

==Test yourself with the Tissue Cyst Forming Coccidian Flashcards==

|literature search = [http://www.cabdirect.org/search.html?rowId=1&options1=AND&q1=%22toxoplasma+gondii%22&occuring1=title&rowId=2&options2=AND&q2=&occuring2=freetext&rowId=3&options3=AND&q3=&occuring3=freetext&publishedstart=2000&publishedend=yyyy&calendarInput=yyyy-mm-dd&la=any&it=any&show=all&x=47&y=7 ''Toxoplasma gondii'' publications since 2000]

|flashcards = [[Tissue_Cyst_Forming_Coccidian_Flashcards|Tissue Cyst Forming Coccidian Flashcards]]

 

==References==

[[Category:Tissue_Cyst_Forming_Coccidia]]

[[Category:Tissue_Cyst_Forming_Coccidia]]

[[Category:To Do - Review]]

[[Category:Expert Review]]