Laboratory diagnosis of giardiasis.

The epidemiology, clinical presentations, and recent developments in understanding Giardia are reviewed. Diagnosis is discussed in light of recent studies that challenge the clinician's approach to the diagnosis of enteric parasites, including giardiasis, and that demonstrate the need for further evaluation on the basis of cost-effectiveness, as well as reliability and clinical practicality. The overall effectiveness and difficulties associated with present standard diagnostic methods and the more recently developed immunologic approaches to diagnosis in giardiasis are reviewed.