Evaluation of different patterns and etiologies of classic formof pyrexia of unknown origin in Assiut University fever unit

Background pyrexia of unknown origin (puo) is one of the most challenging diagnostic dilemmas in clinical practice. despite the availability of different investigations, still diagnosis may not be reached. the aim of the study was to assess the relative frequency of the classical form of puo among patients admitted to the fever unit of assiut university hospital (auh) and to determine the causes and the different fever patterns of the classical form of puo in the studied patients. patients and methods this prospective study included patients with the classical form of puo admitted to fever unit of tropical medicine and gastroenterology of auh during the period from january 2014 till july 2017. all patients who fulfilled the inclusion and exclusion criteria of classical form of puo defined by durack and street were included. results the relative frequency of patients who had classical form of puo was 90 among 2431 (3.7%) patients admitted to the fever unit of tropical medicine and gastroenterology of auh. bacterial infection was on the top of the diagnosis, where 45 (50%) patients had bacterial infections, comprising 14 (15.6%) salmonellosis, 11 (12.2%) tuberculosis, 10 (11.1%) brucellosis, seven (7.7%) pyelonephritis, and three (3.3%) pyogenic liver abscess. different fever patterns were seen, where 58 (64.4%) patients presented with relapsing fever, 29 (32.3%) patients presented with continuous fever, and three (3.3%) patients presented with remittent fever. conclusion puo is detected in 3.7% among feverish patients, where salmonellosis and brucellosis still are the commonest causes. relapsing fever is the commonest pattern of the classical form of puo. undiagnosed puo cases are still a problematic condition that needs exhaustive investigations.