Giardiasis is an infection of the small bowel that occurs mostly as a result of fecal-oral transmission or ingestion of contaminated water containing cysts of the protozoan parasite Giardiaintestinalis, which is the most commonly identified intestinal parasite in the U.S.
The majority of symptoms, which usually develop 1 to 3 weeks after ingesting the cysts, are gastrointestinal and can include acute and chronic diarrhea
The duration of acute giardiasis is usually longer than 1 week and the disease is communicable for as long as the infected person excretes cysts
Testing for Giardia should be considered in patients with persistent diarrhea or signs of malabsorption, immunocompromised patients, or patients with a history that suggests exposure (eg, travel, day care)
Treatment should include asymptomatic patients with evidence of Giardia cysts in stool samples
Antimicrobial medications are effective in most cases; cure rates range from 60% to more than 90%
Severely dehydrated patients require hospitalization to restore electrolyte and fluid balance. This is particularly important in infants and elderly patients