Infections, @entity5 and @entity792 are the most important causes of @entity221 of unknown origin.A case report of a 80-year old @entity1 is described, who was admitted to our hospital because of @entity221 lasting more than 2 weeks, @entity353 and lack of appetite. Physical examination did not provide any relevant information, laboratory tests revealed an elevation of @entity32 markers and @entity417 . Serological tests for infectious and @entity792 and cultures of stool, blood and urine were all negative. Imaging did not show any pathological findings, colonoscopy and gastroscopy were macroscopically normal. Surprisingly, histology showed massive @entity7014 of the duodenum. After initiation of therapy with @entity16909 , @entity221 and @entity32 markers declined and the @entity1 could be discharged from hospital without complaints on the 15(th) day after admission. @entity461 is one of the most common intestinal pathogens worldwide. Infection can cause acute @entity294 , but may also be responsible for chronic abdominal complaints or may stay asymptomatic. To our knowledge, @entity7014 has not been described as differential diagnosis of @entity221 of unknown origin so far. In synopsis of clinical presentation and outcome after antibiotic therapy, we postulate that @entity461 was the relevant cause of @entity221 and @entity353 in this case. In @entity1 presenting with these symptoms, @entity461 should be considered as differential diagnosis.

[Fever and @entity353 as leading symptoms of infection with XXXX ].

@entity1 :: ('9606', 'Species') :: ['patients', 'patient'] @entity32 :: ('MESH:D007249', 'Disease') :: ['inflammation'] @entity353 :: ('MESH:D015431', 'Disease') :: ['weight loss'] @entity417 :: ('MESH:D000740', 'Disease') :: ['anemia'] @entity5 :: ('MESH:D009369', 'Disease') :: ['malignancies'] @entity294 :: ('MESH:D003967', 'Disease') :: ['diarrhea'] @entity792 :: ('MESH:D001327', 'Disease') :: ['autoimmune diseases'] @entity461 :: ('5741', 'Species') :: ['Giardia lamblia'] @entity221 :: ('MESH:D005334', 'Disease') :: ['fever'] @entity7014 :: ('MESH:D005873', 'Disease') :: ['giardiasis'] @entity16909 :: ('CHEBI:6909', 'Chemical') :: ['metronidazol']
@entity461 :: (5741,Species) :: ['giardia lamblia']
