Trichinosis causes: Difference between revisions
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==Life Cycle== | ==Life Cycle== | ||
[[Image:Trichinella_lifecycle.gif| | [[Image:Trichinella_lifecycle.gif|480px|left|thumb|Trichinella life cycle.]] | ||
*Trichinellosis is acquired by ingesting meat containing cysts (encysted larvae) (1) of Trichinella. | *Trichinellosis is acquired by ingesting meat containing cysts (encysted larvae) (1) of 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). | *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). | ||
Revision as of 14:20, 26 January 2016
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Trichinosis Microchapters |
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Trichinosis causes On the Web |
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1] Associate Editor(s)-in-Chief: Danitza Lukac
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.[1]
Causes
The classical agent that causes trichinosis is 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).[1]
Species and characteristics:
| 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
- Trichinellosis is acquired by ingesting meat containing cysts (encysted larvae) (1) of 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).
- After 1 week, the females release larvae (4) that migrate to the striated muscles where they encyst (5).
- Trichinella pseudospiralis, however, does not encyst.
- 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).
References
- ↑ 1.0 1.1 1.2 Trichinosis. Wikipedia. https://en.wikipedia.org/wiki/Trichinosis. Accessed on January 22, 2016
- ↑ 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.