Fever of Unknown Origin (FUO) – A Call for New Research Standards and Updated Clinical Management

Prolonged fever of 38.3°C or higher for at least 3 weeks' duration has been termed fever of unknown origin if unexplained after preliminary investigations. Initially codified in 1961, classification with subgroups was revised in 1991. Additional changes to the definition were proposed in 1997, recommending a set of standardized initial investigations. Advances in diagnosis and management and diagnostic testing over the last 3 decades have...