Medicine Central™ is a quick-consult mobile and web resource that includes diagnosis, treatment, medications, and follow-up information on over 700 diseases and disorders, providing fast answers—anytime, anywhere. Explore these free sample topics:
-- The first section of this topic is shown below --
- Intestinal infection caused by the protozoan parasite Giardia lamblia:
- G. lamblia is also called Giardia duodenalis and Giardia intestinalis.
- Infection results from ingestion of cysts, which transform into trophozoites and colonize the small intestine to cause symptoms.
- Infectious cycle is continued when the trophozoites encyst in the small intestine and are transmitted through water, food, or hands contaminated by feces of an infected person.
- Most infections result from fecal–oral transmission or ingestion of contaminated water (e.g., swimming).
- Less commonly acquired through contaminated food
- Predominant age:
- All ages but most common in early childhood ages 1 to 9 years and adults 35 to 44 years
- Predominant gender:
- Male > female (slightly)
- Minimal seasonal variability; slight increase in summer and early fall
- Most common in early childhood
- Chronic infection in children can lead to intestinal malabsorption (may also be associated with growth restriction).
- 5% of patients with traveller’s diarrhea
- >19,000 cases/year from reportable U.S. states:
- Giardia is not reportable in Indiana, Kentucky, Mississippi, North Carolina, and Texas.
Etiology and Pathophysiology
Giardia trophozoites colonize the surface of the proximal small intestine: The mechanism of diarrhea is unknown.
No known genetic risk factors
- Daycare centers
- Anal intercourse
- Wilderness camping
- Travel to developing countries
- Children adopted from developing countries
- Public swimming pools
- Pets with Giardia infection/diarrhea
- Hand hygiene
- Water purification when camping and when traveling to developing countries
- Properly cook all foods.
Commonly Associated Conditions
Hypogammaglobulinemia, IgA deficiency, and immunosuppression are associated with prolonged course of the disease and treatment failures.