Giardiasis: an overview for the clinician.

Since the clinician confronting a case of giardiasis may find the current literature confusing and weighted towards rare immunoglobulin deficiency syndromes, a classification is proposed to answer questions pertinent to understanding and managing this infection. Current thinking of giardiasis must involve the realization that (1) asymptomatic carriers exist; (2) that the majority of symptomatic patients have no structural disease explaining their symptoms; and (3) that those patients with anatomic lesions and giardiasis probably have an underlying predisposing condition. A short review of the association of giardiasis and immunodeficiency will then be presented, along with current concepts of diagnosis and therapy.