Giardia lamblia: Difference between revisions

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Giardia lamblia
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* Worldwide distribution
 
* Worldwide distribution
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* 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
 
* Numerous animal reservoirs, not fully understood how important they are
 
* 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