# DBT JRF 2020 — Question 67

Exam: DBT JRF 2020 · Section: B · Topic: Microbiology · Difficulty: Easy

## Question

The biological sample used for diagnosis of Giardiasis is

## Options

- **A.** blood
- **B.** sputum
- **C.** urine
- **D.** stool

## Answer

Option D

## Explanation

Giardia lamblia (= G. intestinalis = G. duodenalis) is a flagellated protozoan parasite that infects the small intestine, causing giardiasis (traveller's diarrhoea). Transmission: faecal-oral route via ingestion of cysts in contaminated water or food. Life cycle: cyst (infective form, shed in faeces) → excystation in duodenum → trophozoite (active, attaches to intestinal villi via ventral adhesive disc) → encystment → cysts shed in faeces. Diagnosis: stool microscopy (wet mount for cysts and trophozoites, or stained preparations); stool antigen ELISA/immunochromatography (more sensitive); PCR. Blood, urine, and sputum are NOT appropriate samples as Giardia is confined to the intestinal lumen.

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