Giardia

Question 1

Lab diagnosis of giardiasis

Answer 1

Specimen collection:

Freshly passed stool.
Bile.

Microscopic examination of stool:

Freshly passed stool - Trophozoite, cyst.
Diarrhoeal stool or after a purgative (Saline preparation) - Trophozoite can be seen.
Bile-saline preparation where trophozoite can be seen.
Enterotest (String test): A useful method for obtaining duodenal specimen is enterotest.

Blood test: Eosinophilia.
Serological test: Direct fluorescent antibody (DFA) assay, Enzyme immuno assay (EIA),
immunochromatographic test (ICT) etc. are helpful.

Question 2

Stages of giardiasis.

Answer 2

Stages of Giardia:

Trophozoite
Cyst (Infective form).
Morphology:
Trophozoite:

Size: 14 µm × 7µm.
Shape: Flat view - Tennis or badminton racket shape.
Side on – Longitudinally split pear shape.
Surface: 2 surfaces,
Dorsal - convex
Ventral - concave with sucking shape.
Anterior end: Rounded and broad.
Posterior end: Tapering.
Bilaterally symmetrical. All the body organs in pair. So, contains-
2 nuclei.
2 axostyle, and
4 pairs of flagella

Cyst:

Size: 12µm × 7µm.
Shape: Oval.
Structure:
Axostyle – diagonally
Cyst wall present.
Neuclei - 4 in number, clustered at one end or in pairs at opposite
ends.

Question 2

Name and draw the two forms of giardia lambia found in stool

Answer 2

Question 3

Q. Briefly describe the pathogenesis of giardiasis. [DU-18N,16J]

Answer 3

Pathogenesis of giardiasis: Transmission occurs by ingestion of cysts in fecally contaminated food and water. Excystation takes place in the duodenum, where the trophozoite attaches to the gut wall but does not invade the mucosa and does not enter the bloodstream. The trophozoite causes inflammation of the duodenal mucosa, leading to malabsorption of protein and fat.

Question 4

Write the mode of transmission of Giardia lamblia. [DU-17N]

Answer 4

Mode of transmission of Giardia lamblia:
Transmission occurs by ingestion of cysts in fecally contaminated food and water.