Fever of Unknown Origin in Older Persons

Infectious diseases in general in the aged are associated with higher morbidity and mortality rates. Decremental biologic changes with age affect host defenses and responses to infection, and the frequent presence of comorbidities also may adversely impact host defenses, especially in frail older persons. Infections may present differently in older persons than in younger populations, making early diagnosis difficult. Within this context, the article explores the importance of how fever of unknown origin (FUO) in the old differs significantly from FUO in younger adults because the etiology is different. Moreover, it is important to aggressively determine the etiology of FUO in this older population because it is often treatable.