Giardiasis Flashcards
What is the causative organism of giardiasis?
Giardia lamblia (also known as Giardia intestinalis or Giardia duodenalis), a flagellated protozoan.
What is the primary mode of transmission for Giardia?
Fecal-oral route, primarily through ingestion of cysts in contaminated water or food.
Which populations are at high risk for Giardia infection?
Campers, hikers, individuals drinking untreated or unfiltered water, and those in institutional settings (e.g., daycare centers, nursing homes).
What are the hallmark symptoms of giardiasis?
- Subacute or chronic onset
- Foul-smelling diarrhea
- Bloating
- Flatulence
- Steatorrhea (fatty diarrhea)
- Weight loss due to fat malabsorption.
How does Giardia affect the intestinal mucosa?
Disrupts brush border enzymes and causes villous blunting, leading to malabsorption.
What are the characteristic microscopic findings in Giardia infection?
Pear-shaped, flagellated trophozoites with a ‘smiley-face’ appearance or oval cysts seen in stool samples.
Which diagnostic tests are used for Giardia?
- Ova and parasite (O&P) stool microscopy (low sensitivity)
- Enzyme-linked immunosorbent assay (ELISA) for Giardia antigen
- PCR stool testing
What is the first-line treatment for giardiasis?
- Tinidazole or Nitazoxanide
- Alternative is with Metronidazole
What is the preferred treatment for Giardia in pregnant women (first trimester)?
Paromomycin, as metronidazole is contraindicated in early pregnancy.
Do asymptomatic Giardia carriers require treatment?
Not usually, unless they are at high risk of transmission (e.g., food handlers, immunocompromised individuals, daycare workers).
Why does Giardia cause steatorrhea and weight loss?
Fat malabsorption due to disruption of villous structure and brush border enzymes in the small intestine.
What environmental factors contribute to Giardia outbreaks?
- Contaminated recreational water (lakes and rivers)
- pools due to resistant to chlorination)
- Poor hygiene in crowded institutional settings
How should Giardia outbreaks be controlled in institutional settings?
Symptomatic students with positive stool samples should refrain from using recreational water venues for at least 2 weeks. Recreational water venues are another common source of outbreaks, as cysts often resist chlorination and remain viable in water.
Why is handwashing important for preventing Giardia transmission?
Giardia cysts resist many alcohol-based hand sanitizers, making soap and water washing more effective.
Why is Giardia often resistant to chlorination in water sources?
Cysts have a protective outer layer that allows them to survive chlorinated water.
