Fever is less common in infectious states in the elderly than in young patients. However, in contrast to younger patients, when an elderly patient does have a fever it is much more likely to be associated with a serious bacterial infection. It has been estimated that the source of fever in elderly ED patients is viral in only 5% of cases.
[from Hals G. Common diagnoses become difficult diagnoses when geriatric patients visit the emergency department, part I. Emergency Medicine Reports 2010;31(9):101-110.]
