Lec 3 - Lab 3 Giardia Lamblia

Question 1

Immunity

Answer 1

The humoral immune response and the cellular immune mechanism are involved in giardiasis.

Giardia – specific IgA is particularly important in both defense against and clearance of parasite

Question 2

Life cycle G.lambila

Answer 2

life cycle consists of two stages
the trophozoite is wide 5 -15 m
cyst. 9-12 μm anteriorly

trophozoite is bilaterally symmetrical
pear-shaped
two nuclei (large central karyosome)
four pairs of flagella
two axonemes
suction disc(adhesive disc ) with which it attaches to the intestinal wall

oval cyst is infective stage ,it is 7 μm long and 12-8 μm width
it has thick-walled
four nuclei
several internal fibera
Each cyst gives rise to two trophozoites during excystation in the intestinal tract

Transmission is by ingestion of the infective cyst.

Question 3

Pathogenesis

Answer 3

Infection with G.lamblia is initiated by ingestion of cysts.

Gastric acid stimulates excystation, with the release of trophozoites in duodenum and jejunum.

The trophozoites can attach to the intestinal villi by the ventral sucking discs without penetration of the mucosa lining, but they only feed on the mucous secretions. In symptomatic patients, however, mucosa-lining irritation may cause increased mucous secretion and dehydration.

Metastatic spread of disease beyond the GIT is very rare