Giardiasis - PowerPoint by akashyap



Giardia lamblia
• First intestinal organisms observed under microscope • Discovered by Anton van Leewenhoek in 1681 • He examined specimens of his own stool

General Facts
• Common cause of gastroenteritis • Known as Beaver Fever or Backpacker’s diarrhea (traveler’s diarrhea) • It is the most commonly diagnosed intestinal parasite in the USA • One of the most common waterborne diseases in the USA • Other names: giardia duodenalis giardia intestinalis

Giardia Lamblia
• • Protozoa (single-cell parasite) 4 Groups
1. 2. 3. 4. Amebas -- Entamoeba histolytica Sporozoans -- Cryptosporidium Flagellates -- Giardia Lamblia Ciliates


3 organisms which are important within the intestinal tract

Life cycle consists of 2 stages • Trophozite: pear-shaped, two nuclei, four pairs of flagella, suction disk • Cyst: thick-walled, four nuclei, internal fibers • Produces cysts which are passed in feces

• Feco-oral transmission by ingestion of the cyst in fecally contaminated water • Minimum infective dose: 10-25 cysts • Attaches to the duodenal & jejunal epithelium • Has specific molecules for adhesion to microvilli of epithelial cells • And has its own microvillar sucking disk

• Non-invasive • Causes inflammation of the duodenal mucosa • Causes malabsorption of protein and fat

Clinical Findings
• Mild infections are asymptomatic
– They will be carriers – Will excrete the cysts for years

• More severe infections cause diarrhea
– Watery loose stools – Non bloody – Foul-smelling – fatty

• • • •

Nausea Anorexia Flatulence Abdominal cramps lasting weeks to months • No fever • Weight loss (20-25 lbs.)

• Diarrhea may be self-limiting: 7-10 days • If chronic, it can develop into a serious condition
– Mostly in patients with deficient or compromised immunological defenses

• Infection usually clears up within 2-6 weeks with no other effects • Some may have recurrent episodes or intestinal problems for years long after parasites are cleared

• Found worldwide • Epidemics have occurred with contamination of public drinking supplies • Smaller outbreaks: drinking from rivers and streams contaminated from wild animals

• Hikers who drink untreated stream water are frequently affected • Chlorination does not kill cysts but Filtration removes them

• Can be transmitted sexually among homosexual men as a result of oral-anal contact • High incidence among children in day cares • Communicable between animals and humans zoonotic
– Beavers, dogs, cats, cattle

Lab diagnosis
1. Stools:
• • • find trophozoites or cysts in the diarrheal stools In asymptomatic carriers—only see cysts

2. ELISA test: detects Giardia cyst wall antigen

1. Duodenal intubation, recoverable swallowing capsule, or string test (if microscopic examination of stool is negative)
• • Obtain trophozoites directly from intestine Trophozoites adhere to the object and can be visualized after withdrawal

• Mepacrine hydrochloride • Metronidazole • Tinidazole

Metronidazole (Flagyl)
• Effective against protozoa such as Giardia, Trichomonas, and Entamoeba coli • Also treat infections caused by anaerobic bacteria • Action
– Toxic intermediate formed that damages DNA – Inhibits DNA synthesis

• Not everyone responds to treatment

• Improved treatment of drinking water supplies • Improved sanitation • Boiled, filtered, or iodine treated water in endemic areas • No prophylactic drug or vaccine

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