THE IMMUNE-RESPONSE TO GIARDIA

The flagellate Giardia duodenalis has been considered for many years t o be a commensal living in the lumen of the small intestine of its hos t. It is only 25 years ago that it was accepted that Giardia is a sign ificant pathogen of humans. Knowledge that Giardia can elicit an immun e response that would probably contribute to the onset or absence of s ymptoms is not much older. The use of animal models to study the disea se in the laboratory, together with the production of the whole life c ycle in a test tube, have contributed greatly to our present knowledge of the immune responses to Giardia and of antigens that are specific to the trophozoite or cyst stages. In this review, Gaetan Faubert focu ses on studies published since the last review in Parasitology Today i n 1988, and examines the roles played by the humoral and cell-mediated immune responses in the control of the infection. It also covers the immunodiagnostic assays that have been recently developed on the basis of advances in our knowledge of the antigens of Giardia.