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)
where is variant-specific surface protein found in giardia?
covers entire surface of cell
where do ingested giardia cysts excyst?
duodenum - release two trophozoites
where are trophozoites found in dogs and cats?
dogs - duodenum to ileum
cats - jejunum to ileum
how do giardia trophozoites attach to the brush border of the villus epithelium?
ventral adhesive disk
surface molecules
network of contractile proteins
what are the proposed mechanisms of disease of giardiasis?
apoptosis of enterocytes
loss of epithelial-barrier function
hypersecretion of Cl ions
diffuse microvillus shortening
immune reaction’inhibition of brush-border enzymes and trypsin
interference with bile salt metabolism
where is giardiasis most observed?
young animals - illness typically more severe and persistent
what are the symptoms of giardiasis in dogs and cats?
intermittent diarrhea or soft stools, typically light-colored, mucoid, malodorous, may contain fats, unthrifty appearance & weight loss, occasional vomiting
where is Giardiasis typically a self limiting ilness?
immunocompetent hosts
what species is Giardiasis uncommon?
horses
what are the symptoms of Giardiasis in ruminants?
diarrhea (pasty to fluid, mucoid), decreased appetite, loss of weight
what is seen in cockatiels and buderigars neonates with avian giardiasis?
poor growth and high mortality
what type of birds have most clinical cases of Giardiasis?
buderigars and cockatiels
what species/host is the most implicated in zoonotic transmission of Giardia duodenalis?
beavers
which has a higher prevalence of Giardia duodenalis - shelter dogs and cats or client-owned animals?
shelter dogs and cats
what are some clinical suspicious of giardiasis?
-previous history of it in environment
-diarrhea unresponsive to antibiotic or coccidiostatic treatment
how will a suspected sample of giardiasis be examined under the microscope? (trophozoites and cysts)
-direct saline smear for detection of motile trophozoites
-fecal flotation (zinc sulfate floatation) with centrifugation for detection of cysts
what some fecal immunoassays that can be done to detect giardiasis?
DFA
IFD
ELISA
immunochromatographic assays
antigen detection kits
when is fecal PCR most used for giardiasis?
identify Giardia duodenalis
not normally used to diagnose
what type of diagnostics would be done? If positive for Giardiasis what would be prescribed?
zinc sulfate flotation
giardia lateral flow immunoassay
metronidazole prescribed
which solution was used in each picture - same sample? what flotation solution should be used to detect giardia?
- sheather’s sugar solution
- zinc sulfate solution
does the type of flotation solution matter when detecting giardiasis?
YES
use zinc sulfate solution
In what species is prevention considered impractical since Giardia is so prevalent in the environment?
livestock
what are some prevention and control measures for giardiasis?
enforce strict sanitation and good management
bird - wire floor cages, raised food and water bowls
post - treatment fecal exam
colostrum management and adequate nutrition
what is the feeding stage and infective stage of Giardia?
feeding - trophozoite
infective - cyst
what medications can be used for Giardia in dogs and cats?
Febendazole/metronidazole
what medications can be used for Giardia in ruminants?
febendazole/albendazole
which species with giardia has light-colored, mucoid & malodorous, steatorrhea diarrhea and which has pasty to fluid, mucoid diarrhea?
light-colored, mucoid & malodorous, steatorrhea - dogs and cats
pasty to fluid, mucoid - ruminants
what effect of Giardia is most responsible for the excess water loss?
Excessive secretion of chloride
