Parasitic bowel disease: three pathogens important in primary care.

A high index of suspicion and careful application of diagnostic methods are essential for accurate diagnosis of parasitic bowel diseases. The varied clinical spectrum of giardiasis, amebiasis, and strongyloidiasis emphasizes the need to consider these pathogens when patients present with gastrointestinal complaints. Giardiasis should be suspected in patients, especially returned travelers, with unexplained increase in stool frequency, particularly with bloating, flatulence, or vague systemic symptoms. Amebiasis must be considered in the differential diagnosis of any patient who presents with persistent diarrhea or signs of inflammatory bowel disease. Unexplained diarrheal illnesses associated with upper abdominal symptoms and eosinophilia should raise suspicion of the presence of strongyloidiasis. These findings in a patient with a compromised immune system or in a candidate for immunosuppressive therapy should prompt a thorough investigation to rule out this parasite, since disseminated strongyloidiasis often is fatal.