Giardiasis
Giardiasis: Excerpt from Professional Guide to Diseases (Eighth Edition)
Giardiasis (also called Giardia enteritis or lambliasis) is an infection of the small bowel caused by the symmetrical flagellate protozoan Giardia lamblia. A mild infection may not produce intestinal symptoms. In untreated giardiasis, symptoms wax and wane; with treatment, recovery is complete.
Causes and incidence
G. lamblia has two stages: the cystic stage and the trophozoite stage. Ingestion of G. lamblia cysts in fecally contaminated water or the fecal-oral transfer of cysts by an infected person results in giardiasis. Giardiasis may be transmitted through sexual contact (direct or indirect fecal-oral contact). When cysts enter the small bowel, they become trophozoites and attach themselves with their sucking disks to the bowel's epithelial surface. After this, the trophozoites encyst again, travel down the colon, and are excreted. Unformed feces that pass quickly through the intestine may contain trophozoites as well as cysts.
Giardiasis occurs worldwide but is most common in developing countries and other areas where sanitation and hygiene are poor. In the United States, giardiasis is most common in travelers who have recently returned from endemic areas, and in campers who drink unpurified water from contaminated streams. Probably because of frequent hand-to-mouth activity, children are more likely to become infected with G. lamblia than adults. Hypogammaglobulinemia also appears to predispose people to this disorder. Giardiasis doesn't confer immunity, so reinfections may occur.
Signs and symptoms
Attachment of G. lamblia to the intestinal lumen causes superficial mucosal invasion and destruction, inflammation, and irritation. All of these destructive effects decrease food transit time through the small intestine and result in malabsorption. Such malabsorption produces chronic GI complaints — such as abdominal cramps — and pale, loose, greasy, malodorous, and frequent stools (from 2 to 10 daily) with concurrent nausea. Stools may contain mucus but not pus or blood. Chronic giardiasis may produce fatigue and weight loss in addition to these typical signs and symptoms.
Diagnosis
Suspect giardiasis when travelers to endemic areas or campers who may have drunk unpurified water develop symptoms.
CONFIRMING DIAGNOSIS Actual diagnosis requires laboratory examination of a fresh stool specimen for cysts or examination of duodenal aspirate for trophozoites. An antibody test of the stool for giardiasis is also very effective in diagnosis. A small bowel biopsy shows Giardia.
A barium X-ray of the small bowel may show mucosal edema and barium segmentation. Diagnosis must also rule out other causes of diarrhea and malabsorption.
Treatment
Giardiasis responds readily to a 10-day course of metronidazole or a 7-day course of oral quinacrine and furazolidone. Severe diarrhea may require parenteral fluid replacement to prevent dehydration if oral fluid intake is inadequate.
Special considerations
❑Inform the patient receiving metronidazole of the possible adverse effects of this drug: commonly, headache, anorexia, and nausea and, less commonly, vomiting, diarrhea, and abdominal cramps. Warn against drinking alcoholic beverages, which may provoke a disulfiram-like reaction. If the patient is a woman, ask if she's pregnant because metronidazole is contraindicated during pregnancy.
❑When talking to family members and other suspected contacts, emphasize the importance of stool examinations for G. lamblia cysts.
❑If hospitalization is required, use standard precautions. A child or an incontinent adult requires a private room. Pay strict attention to hand hygiene, particularly after handling feces. Quickly dispose of fecal material. (Normal sewage systems can remove and process infected feces adequately.)
❑Teach good personal hygiene, particularly proper hand-washing technique.
❑To help prevent giardiasis, warn travelers to endemic areas not to drink water or eat uncooked and unpeeled fruits or vegetables (they may have been rinsed in contaminated water). Prophylactic drug therapy isn’t recommended. Advise campers to purify all stream water before drinking it.
❑Report epidemic situations to the public health authorities.
Book Source Details
- Book Title: Professional Guide to Diseases (Eighth Edition)
- Author(s): Springhouse
- Year of Publication: 2005
- Copyright Details: Professional Guide to Diseases (Eighth Edition), Copyright © 2005 Lippincott Williams & Wilkins.
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Copyright notice for book excerpts: Copyright © 2008 Lippincott Williams & Wilkins. All rights reserved.
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