[Urticaria, pruritus].

A 53-year old patient was admitted because of severe urticaria and itching aggravating since 9 months. Laboratory findings like increased sedimentation rate and leucocytosis were suspicious for an infection-associated allergy or a paraneoplastic syndrome. After exclusion of a gastro-intestinal tumor search for the source of a possible infection was intensified by several fecal analyses and trophozoites were found indicating an infestation of the small bowel by Giardia lamblia. Finally lamblia were detected in duodenal aspirate. After therapy with metronidazole 3 x 400 mg/die for 10 days all parameters of infection were normalized and the patient was permanently relieved from symptoms.