Many [ANY diseases affecting all portions of the digestive system are associated with fever either as the sole initial manifestation or as one feature of a combination of symptoms. Among 100 cases of fever of undetermined origin reported by Petersdorf and Beeson,1 24 had disease of the digestive tract; in 19 the disorder, including infections and neoplasm, was primary in the gastrointestinal tract; in 5 tuberculosis, sarcoid, or brucellosis involved the liver in addition to other organs.
The completeness of the initial study of the patient before inclusion in a series of "fever of unknown origin" obviously influences the incidence of certain diseases in such surveys. Thus, complete roentgenogram examination of the gastrointestinal tract usually will identify neoplasm, regional enteritis, or ulcerative colitis, and their incidence among instances of unexplained fever will be low. The same reasoning applies to all other diagnostic procedures thus invalidating comparisons of the incidence