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==Overview==
==Overview==
Common cause of trichinosis include ''[[Trichinella spiralis]]''. Less common causes of trichinosis include ''T. britovi'', ''T. nativa'', ''T. pseudospiralis'', ''T. papuae'', ''T. nelsoni'', ''T. murrelli'', and ''T. zimbabwensis''.<ref name=wiki1234>Trichinosis. Wikipedia. https://en.wikipedia.org/wiki/Trichinosis. Accessed on January 22, 2016</ref>
Trichinosis is caused by ''[[Trichinella spiralis|Trichinella species]]''. The most common species involved in trichinosis is ''T. spiralis''. Less common species include ''T. britovi'', ''T. nativa'', ''T. pseudospiralis'', ''T. papuae'', ''T. nelsoni'', ''T. murrelli'', and ''T. zimbabwensis''.<ref name="wiki1234">Trichinosis. Wikipedia. https://en.wikipedia.org/wiki/Trichinosis. Accessed on January 22, 2016</ref>


==Causes==
==Causes==
The classical agent that causes trichinosis is ''[[Trichinella spiralis|T. spiralis]]'' (found worldwide in many carnivorous and omnivorous animals), but there are several other species of [[Trichinella]] now recognized, including ''T. pseudospiralis'' (mammals and birds worldwide), ''T. nativa'' (Arctic bears), ''T. nelsoni'' (African predators and scavengers), ''T. britovi'' (carnivores of Europe and western Asia), and ''T. papuae'' (wild and domestic pigs, Papua New Guinea and Thailand).<ref name=wiki1234>Trichinosis. Wikipedia. https://en.wikipedia.org/wiki/Trichinosis. Accessed on January 22, 2016</ref>
* Trichinosis is usually caused by ''[[Trichinella spiralis|T. spiralis]]''. ''[[Trichinella spiralis|T. spiralis]]'' is usually found worldwide in many carnivorous and omnivorous animals,  
 
* Other species of [[Trichinella|''Trichinella'']] include:<ref name="wiki1234">Trichinosis. Wikipedia. https://en.wikipedia.org/wiki/Trichinosis. Accessed on January 22, 2016</ref>
Species and characteristics:
** ''T. pseudospiralis'' (mammals and birds worldwide)
{| style="border: 0px; font-size: 90%; margin: 3px;" align=center
** ''T. nativa'' (Arctic bears)
|+ '''Source of Infection and Geographical Distribution of [[Trichinella]] species'''<ref>{{cite journal| author=Gottstein B, Pozio E, Nöckler K| title=Epidemiology, diagnosis, treatment, and control of trichinellosis. | journal=Clin Microbiol Rev | year= 2009 | volume= 22 | issue= 1 | pages= 127-45, Table of Contents | pmid=19136437 | doi=10.1128/CMR.00026-08 | pmc=PMC2620635 | url=http://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=19136437  }} </ref><ref name=wiki1234>Trichinosis. Wikipedia. https://en.wikipedia.org/wiki/Trichinosis. Accessed on January 22, 2016</ref>
** ''T. nelsoni'' (African predators and scavengers)
! style="width: 180px;background: #4479BA"|{{fontcolor|#FFF| Disease}}
** ''T. britovi'' (carnivores of Europe and western Asia)
! style="width: 120px;background: #4479BA"|{{fontcolor|#FFF| Main Source}}
** ''T. papuae'' (wild and domestic pigs, Papua New Guinea and Thailand).
! style="width: 120px;background: #4479BA"|{{fontcolor|#FFF| Geographical Distribution}}
''Species and characteristics'':
{| style="border: 0px; font-size: 90%; margin: 3px;" align="center"
|+ '''Source of Infection and Geographical Distribution of [[Trichinella]] species'''<ref name="wiki1234">Trichinosis. Wikipedia. https://en.wikipedia.org/wiki/Trichinosis. Accessed on January 22, 2016</ref><ref>{{cite journal| author=Gottstein B, Pozio E, Nöckler K| title=Epidemiology, diagnosis, treatment, and control of trichinellosis. | journal=Clin Microbiol Rev | year= 2009 | volume= 22 | issue= 1 | pages= 127-45, Table of Contents | pmid=19136437 | doi=10.1128/CMR.00026-08 | pmc=PMC2620635 | url=http://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=19136437  }} </ref>
! style="width: 180px;background: #4479BA" |{{fontcolor|#FFF| Disease}}
! style="width: 120px;background: #4479BA" |{{fontcolor|#FFF| Main Source}}
! style="width: 120px;background: #4479BA" |{{fontcolor|#FFF| Geographical Distribution}}
|-
|-
| style="width: 120px;font-weight: bold;background: #DCDCDC"| ''T. spiralis''
| style="width: 120px;font-weight: bold;background: #DCDCDC" | ''T. spiralis''
| style="background: #F5F5F5; text-align:center"| Swine  
| style="background: #F5F5F5; text-align:center" | Swine  
| style="background: #F5F5F5; text-align:center"| Cosmopolitan
| style="background: #F5F5F5; text-align:center" | Cosmopolitan
|-
|-
| style="width: 120px;font-weight: bold;background: #DCDCDC"| ''T. britovi''
| style="width: 120px;font-weight: bold;background: #DCDCDC" | ''T. britovi''
| style="background: #F5F5F5; text-align:center"| Wild boar, domesticated pigs
| style="background: #F5F5F5; text-align:center" | Wild boar, domesticated pigs
| style="background: #F5F5F5; text-align:center"| Europe, Asia, northern and western Africa
| style="background: #F5F5F5; text-align:center" | Europe, Asia, northern and western Africa
|-
|-
| style="width: 120px;font-weight: bold;background: #DCDCDC"| ''T. nativa''
| style="width: 120px;font-weight: bold;background: #DCDCDC" | ''T. nativa''
| style="background: #F5F5F5; text-align:center"| Polar bears, Artic foxes, walruses
| style="background: #F5F5F5; text-align:center" | Polar bears, Artic foxes, walruses
| style="background: #F5F5F5; bold; text-align:center"| Arctic, subarctic regions
| style="background: #F5F5F5; bold; text-align:center" | Arctic, subarctic regions
|-
|-
| style="width: 120px;font-weight: bold;background: #DCDCDC"| ''T. papuae''
| style="width: 120px;font-weight: bold;background: #DCDCDC" | ''T. papuae''
| style="background: #F5F5F5; text-align:center"| Wild pigs, saltwater crocodiles
| style="background: #F5F5F5; text-align:center" | Wild pigs, saltwater crocodiles
| style="background: #F5F5F5; text-align:center"| Papua New Guinea, Thailand
| style="background: #F5F5F5; text-align:center" | Papua New Guinea, Thailand
|-
|-
| style="width: 120px;font-weight: bold;background: #DCDCDC"| ''T. nelsoni''
| style="width: 120px;font-weight: bold;background: #DCDCDC" | ''T. nelsoni''
| style="background: #F5F5F5; text-align:center"| Warthogs, bush pigs
| style="background: #F5F5F5; text-align:center" | Warthogs, bush pigs
| style="background: #F5F5F5; text-align:center"| Eastern Africa
| style="background: #F5F5F5; text-align:center" | Eastern Africa
|-
|-
| style="width: 120px;font-weight: bold;background: #DCDCDC"|''T. murrelli''
| style="width: 120px;font-weight: bold;background: #DCDCDC" |''T. murrelli''
| style="background: #F5F5F5; text-align:center"|Black bear
| style="background: #F5F5F5; text-align:center" |Black bear
| style="background: #F5F5F5; text-align:center"|North America
| style="background: #F5F5F5; text-align:center" |North America
|-
|-
| style="width: 120px;font-weight: bold;background: #DCDCDC"|''T. zimbabwensis''
| style="width: 120px;font-weight: bold;background: #DCDCDC" |''T. zimbabwensis''
| style="background: #F5F5F5; text-align:center"|Nile crocodiles, monitor lizards
| style="background: #F5F5F5; text-align:center" |Nile crocodiles, monitor lizards
| style="background: #F5F5F5; text-align:center"|Zimbabwe, Mozambique, Ethiopia, South Africa
| style="background: #F5F5F5; text-align:center" |Zimbabwe, Mozambique, Ethiopia, South Africa
|-
|-
|}
|}


==Life Cycle==
==Life Cycle==
[[Image:Trichinella_lifecycle.gif|480px|left|thumb|Trichinella life cycle.]]
[[Image:Trichinella_lifecycle.gif|500px|left|thumb|Trichinella life cycle.]]
*Trichinellosis is acquired by ingesting meat containing cysts (encysted larvae) (1) of Trichinella.  
*Trichinosis is acquired by ingesting meat containing [[cysts]] (encysted larvae) (life cycle stage: 1) of [[Trichinella|''Trichinella'']].
*After exposure to gastric acid and pepsin, the larvae are released (2) from the cysts and invade the small bowel mucosa where they develop into adult worms (3) (female 2.2 mm in length, males 1.2 mm; life span in the small bowel: 4 weeks).  
*Sylvatic cycle: Pigs become infected when they eat infectious [[cysts]] in raw meat, often pork or rats.
*After 1 week, the females release larvae (4) that migrate to the striated muscles where they encyst (5).
*Domestic cycle: Humans become infected when they eat raw or undercooked infected pork.
*Trichinella pseudospiralis, however, does not encyst.  
*After exposure to [[gastric acid]] and [[pepsin]], the larvae are released (life cycle stage: 2) from the [[cysts]] and invade the [[small bowel]] mucosa where they develop into adult worms (life cycle stage: 3) (female 2.2 mm in length, males 1.2 mm; life span in the [[small bowel]]: 4 weeks).  
*After 1 week, the females release larvae (life cycle stage: 4) that migrate to the striated [[muscles]] where they encyst (life cycle stage: 5).  
*Encystment is completed in 4 to 5 weeks and the encysted larvae may remain viable for several years.  
*Encystment is completed in 4 to 5 weeks and the encysted larvae may remain viable for several years.  
*Ingestion of the encysted larvae perpetuates the cycle.  
*Ingestion of the encysted larvae perpetuates the cycle.  
*Rats and rodents are primarily responsible for maintaining the endemicity of this infection.  
*Rats and rodents are primarily responsible for maintaining the [[Endemic (epidemiology)|endemicity]] of this infection.  
*Carnivorous/omnivorous animals, such as pigs or bears, feed on infected rodents or meat from other animals.  
*Carnivorous/omnivorous animals, such as pigs or bears, feed on infected rodents or meat from other animals.  
*Different animal hosts are implicated in the life cycle of the different species of Trichinella.  
*Different animal hosts are implicated in the life cycle of the different species of [[Trichinella|''Trichinella'']].  
*Humans are accidentally infected when eating improperly processed meat of these carnivorous animals (or eating food contaminated with such meat). <ref name=a>Trichinellosis. CDC. http://www.cdc.gov/parasites/trichinellosis/biology.html. Accessed on January 26, 2016</ref>
*Humans are accidentally infected when eating improperly processed meat of these carnivorous animals (or eating food contaminated with such meat).<ref name="wiki1234">Trichinosis. Wikipedia. https://en.wikipedia.org/wiki/Trichinosis. Accessed on January 22, 2016</ref><ref name="a">Trichinellosis. CDC. http://www.cdc.gov/parasites/trichinellosis/biology.html. Accessed on January 26, 2016</ref>
 
 
 
 


==References==
==References==
{{reflist|2}}
{{reflist|2}}
[[Category:Conditions diagnosed by stool test]]
[[Category:Infectious disease]]
[[Category:Needs content]]
{{WH}}
{{WS}}

Latest revision as of 19:00, 18 September 2017

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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1] Associate Editor(s)-in-Chief: Danitza Lukac

Overview

Trichinosis is caused by Trichinella species. The most common species involved in trichinosis is T. spiralis. Less common species include T. britovi, T. nativa, T. pseudospiralis, T. papuae, T. nelsoni, T. murrelli, and T. zimbabwensis.[1]

Causes

  • Trichinosis is usually caused by T. spiralis. T. spiralis is usually found worldwide in many carnivorous and omnivorous animals,
  • Other species of Trichinella include:[1]
    • T. pseudospiralis (mammals and birds worldwide)
    • T. nativa (Arctic bears)
    • T. nelsoni (African predators and scavengers)
    • T. britovi (carnivores of Europe and western Asia)
    • T. papuae (wild and domestic pigs, Papua New Guinea and Thailand).

Species and characteristics:

Source of Infection and Geographical Distribution of Trichinella species[1][2]
Disease Main Source Geographical Distribution
T. spiralis Swine Cosmopolitan
T. britovi Wild boar, domesticated pigs Europe, Asia, northern and western Africa
T. nativa Polar bears, Artic foxes, walruses Arctic, subarctic regions
T. papuae Wild pigs, saltwater crocodiles Papua New Guinea, Thailand
T. nelsoni Warthogs, bush pigs Eastern Africa
T. murrelli Black bear North America
T. zimbabwensis Nile crocodiles, monitor lizards Zimbabwe, Mozambique, Ethiopia, South Africa

Life Cycle

Trichinella life cycle.
  • Trichinosis is acquired by ingesting meat containing cysts (encysted larvae) (life cycle stage: 1) of Trichinella.
  • Sylvatic cycle: Pigs become infected when they eat infectious cysts in raw meat, often pork or rats.
  • Domestic cycle: Humans become infected when they eat raw or undercooked infected pork.
  • After exposure to gastric acid and pepsin, the larvae are released (life cycle stage: 2) from the cysts and invade the small bowel mucosa where they develop into adult worms (life cycle stage: 3) (female 2.2 mm in length, males 1.2 mm; life span in the small bowel: 4 weeks).
  • After 1 week, the females release larvae (life cycle stage: 4) that migrate to the striated muscles where they encyst (life cycle stage: 5).
  • Encystment is completed in 4 to 5 weeks and the encysted larvae may remain viable for several years.
  • Ingestion of the encysted larvae perpetuates the cycle.
  • Rats and rodents are primarily responsible for maintaining the endemicity of this infection.
  • Carnivorous/omnivorous animals, such as pigs or bears, feed on infected rodents or meat from other animals.
  • Different animal hosts are implicated in the life cycle of the different species of Trichinella.
  • Humans are accidentally infected when eating improperly processed meat of these carnivorous animals (or eating food contaminated with such meat).[1][3]

References

  1. ↑ 1.0 1.1 1.2 1.3 Trichinosis. Wikipedia. https://en.wikipedia.org/wiki/Trichinosis. Accessed on January 22, 2016
  2. ↑ Gottstein B, Pozio E, Nöckler K (2009). "Epidemiology, diagnosis, treatment, and control of trichinellosis". Clin Microbiol Rev. 22 (1): 127–45, Table of Contents. doi:10.1128/CMR.00026-08. PMC 2620635. PMID 19136437.
  3. ↑ Trichinellosis. CDC. http://www.cdc.gov/parasites/trichinellosis/biology.html. Accessed on January 26, 2016
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