Giardiasis

Question 1

what type of parasite is Giardia?

Answer 1

intestinal commensal
flagellate protozoa in upper GI tract
monoxenous (species specific)

Question 2

which species is Giardia commonly found?

Answer 2

vertebrates such as humans, companion animals, livestock, wild animals
worldwide

Question 3

what is the feeding stage of Giardia and how does it divide?

Answer 3

Trophozoite divides by binary fission

Question 4

describe the trophozoite stage of Giardia

Answer 4

bilaterally symmetric
Pyriform (tear drop) shape
two nuclei

Question 5

describe the cyst stage of Giardia

Answer 5

thick walled
4 nuclei
trophozoites release from cysts

Question 6

how many trophozoites release from cysts?

Answer 6

two

Question 7

ID the Giardia stage

Answer 7

trophozoite

Question 8

ID the Giardia stage

Answer 8

cyst

Question 9

what causes Giardia?

Answer 9

G. duodenalis aka G. lamblia/intestinalis/enterica

Question 10

what does this diagram demonstrate?

Answer 10

the genetic assemblages of Giardia duodenalis

Question 11

what species make up genetic assemblage A & B?

Answer 11

wide range of domestic and wild animals (include humans)
Sub AI = domestic livestock and pets
Sub AII = humans

Question 12

what species make up genetic assemblage C & D?

Answer 12

dogs and wild canids
NEVER found in humans

Question 13

what species make up genetic assemblage E?

Answer 13

hoofed stock
such as cattle, sheep, goats, pigs, horses

Question 14

what species make up genetic assemblage F?

Answer 14

cats

Question 15

what species make up genetic assemblage G?

Answer 15

rodents

Question 16

what species make up genetic assemblage H?

Answer 16

seals

Question 17

list the modes of transmission of Giardia?

Answer 17

direct fecal ingestion of cysts
indirect ingestion of contaminated water, food, transport hosts, infected prey
re-infection from animal fur when they groom

Question 18

what’s the prepatent period of Giardia in dogs?

Answer 18

4-12 days
average 8 days

Question 19

what’s the prepatent period of Giardia in cats?

Answer 19

5-16 days
average 10 days

Question 20

describe the importance of virulence-specific surface protein (VSP)?

Answer 20

cysteine rich surface protein
covers entire giardial trophozoite cell
main factor responsible for immune evasion

Question 21

where are Giardia trophozoites most commonly found in dogs?

Answer 21

duodenum to ileum

Question 22

where are Giardia trophozoites most commonly found in cats?

Answer 22

jejunum and ileum

Question 23

where are Giardia cysts found in dogs/cats?

Answer 23

duodenum, releases two trophozoites

Question 24

describe the proposed mechanism of Giardia

Answer 24

1. trophozoites bind to GI tract
2. apoptosis of enterocytes
3. loss of epithelial barrier function
4. hypersecrete Cl-
5. diffuse microvillus shortening
6. immune reaction
7. inhibit brush border enzymes and trypsin
8. interference with bile salt metabolism

Question 25

describe the symptoms of Giardia

Answer 25

often asymptomatic (shed cysts in feces)
self-limiting illness in immunocompromised

Question 26

who is Giardia most common in?

Answer 26

young animals
illness is more severe and persistent

Question 27

how would the feces of a dog/cat look if they likely had Giardia?

Answer 27

greasy stool
light colored, mucoid, malodorous (smells bad)
may or may not be D

Question 28

what is the main Giardia species in birds?

Answer 28

G. psittaci

Question 29

which birds most commonly get G. psittaci?

Answer 29

parrots, specifically budgerigars and cockatiels
they also have increased mortality for an unknown reason

Question 30

what’s the zoonotic potential for G. duodenalis?

Answer 30

very few direct animal to human cases
beavers most common for zoonotic transmission in USA

Question 31

how would you cliinically diagnose Giardia?

Answer 31

clinical suspicion (history at farm/home, D unresponsive to other treatments)
microscopic exam of fresh feces
fecal immunoassays
fecal PCR