changing pattern of infectious etiology of fever of unknown origin (fuo) in adult patients in ahvaz, iran

background: although infectious diseases are the most common sources for the fever of unknown origin (fuo), but the spectrum of infectious diseases is changing overtime. the purpose of the study was to define the clinical spectrum and changing the pattern of fuo.methods: this existing data based study was undertaken from 2007 to 2011. one hundred-six patients fulfilling the modified criteria for fuo referred in a teaching hospital in ahvaz were enrolled for analysis. the data extracted from the patient's medical files and etiologic agents caused fuo to be assessed.results: infections were the most common cause of fuo in 48.4% of the patients. among the infections, the most important causes of fuo were represented by extra-pulmonary tuberculosis 15 (31.9%), osteomyelitis 10 (21.3%) and abdominal abscesses 6 (12.8%).conclusion: the pattern of fuo in the region is thought to be changed to extra pulmonary tb and osteomyelitis. tuberculosis is still the leading cause of fuo in our region.