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Giardiasis (Giardia, traveler's diarrhea)
Primary Distribution: Worldwide
Vector and Agent: Giardia lamblia is a protozoan transmitted via water or food contaminated with human feces. Giardiasis is also transmitted sexually (usually anal-oral).
Incubation: 1-3 weeks or longer.
Clinical Findings and Treatment
Signs and Symptoms: Although many infected persons are asymptomatic, others experience diarrhea as the primary symptom. Diarrhea ranges from one loose stool/day to frequent copious watery stools, may be acute or chronic, and continuous or intermittent (with bouts of constipation). When copious, stools often contain mucous, but seldom blood, and are pale, frothy, greasy/steatorrheic, and foul-smelling. Other common symptoms are abdominal pain (which may be predominant), nausea and vomiting, anorexia, flatulence, fatigue, and weight loss. The acute phase may last days or weeks, with resolution usually spontaneous. Some patients develop chronic giardiasis, in which abdominal pain, flatus, and belching are more common than diarrhea. Chronic giardiasis may feature looses stools, and if severe, weight loss.
Complications: Malabsorption with weight loss, dehydration, and in infants and young children, inhibited growth and development.
Laboratory Findings:
Diagnosis: Three stool samples taken over two days are examined microscopically. Coproantigen tests by ELISA and IFA are available.
Differential Diagnosis: Any diarrheal illness.
Treatment: Metronidazole 250 mg. tid x 5 days is a common treatment. Alternatives include furazolidone, albendazole, and paramomycin. Empiric treatment is common.
References
Centers for Disease Control (1996). Surveillance for waterborne disease outbreaks: United States, 1993-94. Available online: ftp://ftp.cdc.gov/pub/Publications/mmwr/ss/ss4501.pdf
Centers for Disease Control (1999). Giardiasis. Available online: ftp://ftp.cdc.gov/ncidod/dpd/giardias.htm
Goldsmith, R.S. (1999). Infectious diseases: Protozoal and helminthic. In L.M. Tierney, S.J. McPhee, & M.A. Papadakis (Eds.), Current Medical Diagnosis & Treatment (14th ed.) (pp.1353-1417). Stamford Connecticut: Appleton & Lange.