Giardia lamblia: Difference between revisions
From IDWiki
Giardia lamblia
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* Worldwide distribution |
* Worldwide distribution |
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* Numerous animal reservoirs, not fully understood how important they are |
* Numerous animal reservoirs, not fully understood how important they are |
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* Cysts can survive several months in cold water |
* Cysts can survive several months in cold water |
Revision as of 21:22, 8 October 2019
- A member of the Giardia species that causes intestinal disease (giardiasis) in humans and animals
- Also known as beaver fever
Microbiology
- Flagellated protozoan that infects the small bowel
- Host specificity related to genotype ("assemblage")
- Assemblages A & B infect humans, but also numerous non-human hosts including primates, dogs, cars, cattle, sheep, deer, rodents, horses, and beavers
- Assemblages C & D affect dogs; E affects cattle, goats, sheep, and pigs; F affects cats; G affects rodents; and H affects marine vertebrates
- Antigenic variation is determined by the variant-specific surface protein (VSP)
- Replaced every few generations
Life Cycle
- A cyst is ingested via fecal-oral contamination
- In the small bowel, the cyst releases two trophozoites (free-living form) via excystation
- Trophozoites multiply by binary fission
- When they reach the large bowel, they encyst
Epidemiology
- Worldwide distribution
- Generally transmitted fecal-oral route (via environment), but person-to-person transmission is possible in daycares
- Numerous animal reservoirs, not fully understood how important they are
- Cysts can survive several months in cold water
- Peak prevalence occurs in children of up to 15 to 30% in poor countries