Etiology of Fever of Unknown Origin in Shiraz: A Southern Iranian Experience

Although infectious diseases are the most common cause of fever of unknown origin (FUO) in many countries, the spectrum of its etiology is changing over time.

The purpose of this study was to determine the clinical spectrum and the pattern of FUO in Shiraz.

This study was undertaken from 2011 to 2015 in the main hospitals of Shiraz, southern Iran. The data of 60 patients fulfilling the modified criteria for FUO referring to the main hospitals in Shiraz were used for analysis. The data were extracted from the patients’ medical charts and probable etiologies responsible for FUO were assessed. The patients were followed up by further ambulatory and readmission assessment.

Of the identified etiologies, infections were the most common cause of FUO in 30% of the patients, followed by collagen vascular diseases with 15% and malignancies with 11.6%. However, 25 patients (41%) remained undiagnosed for their fever causes.

The pattern of FUO in the region has changed in recent years and complicated cases are admitted to hospitals. With improving ambulatory tests and diagnostic modalities, most of the patients with FUO are being diagnosed in outpatient settings and it will cause some changes in the classic percentage of FUO etiologies among admitted patients in the future.