Giardiasis Flashcards
what are the causative agents of giardiasis?
Giardia duodenalis
Giardia psittaci
what species get infected with Giardia duodenalis?
livestock, companion animals, humans
what species get infected with Giardia psittaci?
birds
what type of protozoan is Giardia and where does it infect?
flagellate protozoan
infect - upper GI tract
Is giardia monoxenous or heterozenous?
monoxenous - direct life cycle
how do trophozoites divide in Giardia spp.?
binary fission
what are the key characteristics of Giardia trophozoites?
pyriform shape - anterior end broad and rounded
concave, ventral adhesive disc
two nuclei
two median (parabasal) bodies
two axostyles
four pairs of flagella
what is a key characteristic of the Giardia trophozoite that is unique to the genus?
median bodies
what are the key characteristics of Giardia cysts?
thick walleed cyst
contain 4 nuclei when mature
two trophozoites released from cyst
excystation triggered by gastric acid, pancreatic enzymes, and bile salts
how many trophozoites are released from a giardia cyst?
2
what triggers the excystation of giardia cysts?
gastric acid, pancreatic enzymes, and bile salts
how many genetic assemblages does Giardia duodenalis have?
8
what are the 8 genetic assemblages of Giardia duodenalis?
A&B - wide range of domestic and wild animals
C&D - dogs and wild canids
E - hoofed stock
F - cats
G - rodents
H - seals
how is Giardia duodenalis transmitted?
direct ingestion of fecal Giardia cysts
indirect ingestion of contaminated water, food, transport hosts, infected prey species, or fomites
re-infection from animal fur when they groom
what is the prepatent period for Giardia duodenalis in dogs and cats?
dogs - 4-12 days (mean 8 days)
cats - 5-16 days (mean 10 days)
Is Giardia more prevalent in puppies or kittens?
puppies
what are the major virulence factors of Giardia spp.?
attachment
circumvention of natural factors of intestinal lumen
antigeni variation
alteration of host innate defenses
anti-inflammatory modifications
survival in stomach acid and external environment
what is the main factor responsible for immune evasion in Giardia?
variant-specific surface protein (VSP)