(Pediatrics in Review. 1997;18:243-247.)
© 1997 American Academy of Pediatrics
Giardia
Gloria Heresi, MD*
Thomas G. Cleary, MD
*
Fellow, Pediatric Infectious Diseases.
Director, Pediatric Infectious Diseases,
University of Texas-Houston Health
Sciences Center, Houston, TX.
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IMPORTANT POINTS
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- Most patients who have Giardia lamblia infections
are asymptomatic.
- In the majority of patients diagnosed with G lamblia
infection, the medical history, physical examination, and stool studies are
sufficient to make the diagnosis.
- Giardiasis in the United States is
frequent in child care centers, facilities for the mentally retarded, family
members of an index case, campers, and children in swimming classes.
- Empiric treatment of giardiasis is advised in children who present with
chronic diarrhea and malabsorption symptoms and negative stool studies
before a more aggressive diagnostic approach is initiated.
- Improvement in level of hygiene is the best way to interrupt transmission of infections
in institutions.
Giardia lamblia is a protozoan parasite that has a worldwide distribution;
in the United States and most other highly industrialized countries, it is
the intestinal parasite identified most commonly. G lamblia was identified
in 1681 by Von Leewenhock in his stools, and for centuries it was thought to
represent a nonpathogenic organism. In the past 20 years, however, data have
accumulated demonstrating that, at times, G lamblia can be a pathogen,
causing disease in both sporadic and epidemic forms. Nevertheless, the
majority of human infections are asymptomatic.
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Etiology
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G lamblia is a
flagellated protozoa that has two life cycle stages: trophozoite and cyst.
The trophozoite usually is seen in preparations of duodenal mucosa or fresh
diarrheic stools. It is pear-shaped and dorsally convex with a spiral
organelle, the sucking disk, on the ventral surface, which is its mode of
attachment to the mucosal surface. The trophozoite is 10 to 21 mcm in length
and 5 to 15 mcm in width, with two symmetric nuclei and four pairs of
flagella. It resembles a human face on stained preparations. The cyst, the
most common form seen in stool, is oval, measures 8 to 12 mcm long and 5 . . . [Full Text of this Article]
Copyright © 1997 by the American Academy of Pediatrics.