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Get a grip on giardiasis

Elkins, Mary Y. MPH, RN

doi: 10.1097/01.NURSE.0000384106.45889.75


Mary Y. Elkins is an infection control practitioner at Northern Navajo Medical Center in Shiprock, N.M.

A DIARRHEAL INFECTION caused by the protozoan parasite Giardia intestinalis, giardiasis is a common cause of waterborne illness in the United States. The parasite lives in the intestines of infected humans and animals and is passed in feces. It can live outside the body for months and is found on surfaces or in soil, food, or water that's been contaminated with feces from infected humans and animals.1 Most Giardia infections result from the ingestion of infective cysts via fecal-oral transmission, usually the handling and ingestion of contaminated water or food. Person-to-person infection is also common.2

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Recognizing giardiasis

The incubation period for giardiasis varies from 1 to 14 days; the acute stage lasts 1 to 3 weeks.3 Signs and symptoms usually begin about 2 weeks after infection with a feeling of intestinal discomfort followed by nausea and anorexia. High fever isn't generally associated with giardiasis, but low-grade fever and chills may be present before explosive, watery, foul-smelling diarrhea begins. Some patients experience abdominal distension and hyperactive bowel sounds. This acute stage may pass in 3 to 4 days without treatment, but intermittent diarrhea may occur in the subacute or chronic form of the illness for several years or more. In otherwise healthy patients, signs and symptoms of giardiasis may last 2 to 6 weeks.2

Complications associated with giardiasis include development of chronic illness, malabsorption syndrome, and failure to thrive, especially in children. Rare complications include arthritis, retinal arteritis, cholecystitis, iridocyclitis, and pancreatitis.2

Assessment of the patient's travel history and sources of water intake can help the healthcare provider diagnose giardiasis, along with examination of the stool for Giardia ova and parasites. At least three stool specimens should be taken at 2-day intervals.2 Commercially available tests, including an immunofluorescent antibody assay and a capture enzyme-linked immunosorbent assay, are available to detect Giardia antigen in the stool. They have a sensitivity of 85% to 98% and a specificity of 90% to 100%.2

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Treatment and prevention

Because most cases of giardiasis are asymptomatic or minimally symptomatic, treatment isn't always necessary. If it's required, the most commonly prescribed antimicrobial is oral metronidazole, given for 5 to 7 days. Inform patients about the common adverse reactions of the medication, including a metallic taste, nausea, dizziness, and headache.2 Although not specifically contraindicated in adults, antidiarrheal medications should be avoided if there's accompanying fever, bloody stools, or abdominal pain other than cramps.4

Ensure adequate restoration of volume status with oral hydration or I.V. crystalloid solution if prescribed for dehydration.2 Provide breastfeeding patients with education regarding effective hand hygiene to prevent transmission of Giardia to the infant. Suggest alternatives to breast milk if the healthcare provider recommends avoidance of breastfeeding while on a specific drug therapy for giardiasis.5

Nosocomial transmission of giardiasis can occur due to poor staff hand hygiene, so be sure to use standard precautions and meticulous hand hygiene. Use contact precautions for diapered or incontinent patients for the duration of the illness.6 Examine close contacts of the patient for giardiasis and provide treatment if diagnosed.2

To prevent Giardia transmission, teach patients to practice good hand hygiene. Instruct them to use a barrier during oral-anal sex and to wash hands after handling a condom used during anal sex.1

Advise patients not to swim in recreational water or allow their children to do so when they have diarrhea and for 1 week after diarrhea stops. They can help keep Giardia out of recreational water by taking children on frequent bathroom breaks, checking diapers often, and changing diapers away from the water area. Teach patients not to swallow recreational water or drink untreated water or ice, especially when traveling internationally.1

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1. Centers for Disease Control and Prevention. Giardia infection: giardiasis .
2. Pennardt A. Giardiasis .
3. Centers for Disease Control and Prevention Division of Parasitic Diseases. Parasites and health: giardiasis .
4. Treating diarrhea: if basics aren't enough. Mayo Clin Health Lett. 2010;28(2):6.
5. Leder K, Weller P. Patient information: Giardia .
6. Siegel JD, Rhinehart E, Jackson M, Chiarello L, Healthcare Infection Control Practices Advisory Committee. 2007 guideline for isolation precautions: preventing transmission of infectious agents in healthcare settings .
© 2010 Lippincott Williams & Wilkins, Inc.