12 Questions
What is the function of encystation specific vesicles (ESV) in the parasite?
Synthesizing the cyst wall protein antigens
How many nuclei does the cyst form of the parasite typically contain?
Four
What is a unique feature of the cyst form of the parasite?
Retraction of flagella during encystation
What is the role of parabasal bodies in the parasite?
Forming part of the axoneme structure
Which feature gives the cyst form of the parasite its 'old man's face/old man with eyeglasses appearance' resemblance?
Central karyosome
What initiates the process of encystation in the parasite?
Retraction of flagella
What is the most common cause of intestinal infection worldwide according to Bailey's?
Giardia lamblia
Where is the habitat of Giardia lamblia in the human body?
Duodenum and upper part of jejunum
How is the trophozoite of Giardia lamblia typically shaped when viewed from the front?
Pear shaped
What feature distinguishes Giardia lamblia as bilaterally symmetrical among protozoan parasites?
Bilaterally symmetrical
How does Giardia lamblia attach to the intestinal epithelium?
By means of the sucking disc
Who were Giardia lamblia named after?
Prof. A. Giard and Dr. F. Lambl
Study Notes
Giardia Lamblia Structure
- Has a pair of median bodies and a pair of parabasal bodies connected to basal bodies
- Possesses one pair of nuclei, each with a large karyosome within the sucking disk
- Has a characteristic "old man's face" or "old man with eyeglasses" appearance
- Exhibits "falling leaf-like" motility
Cyst Stage
- Ovoid in shape
- Contains two to four nuclei, remnants of axonemes, basal bodies, and parabasal bodies
- Is the infective and diagnostic form of the parasite
- Encystation specific vesicles (ESV) appear in the cytoplasm to process and transport cyst wall protein antigens
Epidemiology
- Most common cause of intestinal infection worldwide
- Most common protozoan pathogen, with a worldwide distribution
- Leading cause of diarrhea in patients with immunodeficiency syndromes
Habitat and Characteristics
- Found in the duodenum and upper part of the jejunum
- Trophozoite is pear-shaped (or tear drop or tennis racket shaped) in front view and spoon/sickle shaped in lateral view
- Bilaterally symmetrical, the only protozoan with this characteristic
- Remains in the lumen of the human small intestine and does not invade tissue
History and Clinical Significance
- First observed by A.V. Leeuwenhoek in 1681
- Named after Dr. F. Lambl of Prague and Prof. A. Giard of Paris in 1859
- Causative agent of Giardiasis, Traveller's diarrhea, and Gay Bowel Syndrome
- Tightly adheres to intestinal epithelium by means of the sucking disc
Test your knowledge on the characteristic morphological features of Giardia lamblia, including pair of median bodies, old man's face appearance, and falling leaf-like motility. Identify the key structures and characteristics of this parasite.
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