Paper I
Question
Laboratory diagnosis of Giardiasis.
Answer
Laboratory diagnosis of giardiasis (Giardia lamblia):
- Stool microscopy — for cysts (oval, thick-walled, containing four nuclei when mature, typically found in formed stool) and/or trophozoites (pear-shaped, two nuclei giving an “owl’s-eye” appearance, four pairs of flagella, ventral adhesive disc, typically found in loose/watery stool); repeated sampling on different days improves sensitivity given intermittent cyst shedding.
- Stool antigen ELISA — more sensitive than microscopy.
- String test (Entero-test) — recovers duodenal fluid/mucus for trophozoite examination when stool exam is negative but suspicion remains.
- PCR — where available, highly sensitive.
Treatment: metronidazole (or tinidazole).