Giardiasis: a common cause of diarrheal disease

Giardiasis has been reported increasingly among visitors to the Soviet Union and is found at epidemic and endemic levels in the United States. The main source of infection is contaminated water. Children, homosexual males, and patients with gastrectomy, achlorhydria, hypogammaglobulinemia, secretory IgA deficiency, or alteration in immune status are particularly susceptible to severe, often chronic, infection. Symptomatic giardiasis can be acute, subacute, or chronic. Symptoms are explosive, watery, foul-smelling stools or semisolid stools with evidence of steatorrhea; flatulence; abdominal distention; and weight loss. Diagnosis usually can be established by examination of stool or duodenal fluid for cysts or trophozoites. Quinacrine hydrochloride is the drug preferred for treatment, but metronidazole and furazolidone are also useful.