Giardia lamblia
From IDWiki
- 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
- 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