Giardiasis

Question 1

What is the causative organism of giardiasis?

Answer 1

Giardia lamblia (also known as Giardia intestinalis or Giardia duodenalis), a flagellated protozoan.

Question 2

What is the primary mode of transmission for Giardia?

Answer 2

Fecal-oral route, primarily through ingestion of cysts in contaminated water or food.

Question 3

Which populations are at high risk for Giardia infection?

Answer 3

Campers, hikers, individuals drinking untreated or unfiltered water, and those in institutional settings (e.g., daycare centers, nursing homes).

Question 4

What are the hallmark symptoms of giardiasis?

Answer 4

• Subacute or chronic onset
• Foul-smelling diarrhea
• Bloating
• Flatulence
• Steatorrhea (fatty diarrhea)
• Weight loss due to fat malabsorption.

Question 5

How does Giardia affect the intestinal mucosa?

Answer 5

Disrupts brush border enzymes and causes villous blunting, leading to malabsorption.

Question 6

What are the characteristic microscopic findings in Giardia infection?

Answer 6

Pear-shaped, flagellated trophozoites with a ‘smiley-face’ appearance or oval cysts seen in stool samples.

Question 7

Which diagnostic tests are used for Giardia?

Answer 7

• Ova and parasite (O&P) stool microscopy (low sensitivity)
• Enzyme-linked immunosorbent assay (ELISA) for Giardia antigen
• PCR stool testing

Question 8

What is the first-line treatment for giardiasis?

Answer 8

• Tinidazole or Nitazoxanide
• Alternative is with Metronidazole

Question 9

What is the preferred treatment for Giardia in pregnant women (first trimester)?

Answer 9

Paromomycin, as metronidazole is contraindicated in early pregnancy.

Question 10

Do asymptomatic Giardia carriers require treatment?

Answer 10

Not usually, unless they are at high risk of transmission (e.g., food handlers, immunocompromised individuals, daycare workers).

Question 11

Why does Giardia cause steatorrhea and weight loss?

Answer 11

Fat malabsorption due to disruption of villous structure and brush border enzymes in the small intestine.

Question 12

What environmental factors contribute to Giardia outbreaks?

Answer 12

• Contaminated recreational water (lakes and rivers)
• pools due to resistant to chlorination)
• Poor hygiene in crowded institutional settings

Question 13

How should Giardia outbreaks be controlled in institutional settings?

Answer 13

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.

Question 14

Why is handwashing important for preventing Giardia transmission?

Answer 14

Giardia cysts resist many alcohol-based hand sanitizers, making soap and water washing more effective.

Question 15

Why is Giardia often resistant to chlorination in water sources?

Answer 15

Cysts have a protective outer layer that allows them to survive chlorinated water.