In Japan, an actual condition survey on childhood febrile diseases with fever of unknown origin has never been performed. We carried out a national survey on childhood febrile illnesses in order to collect useful information for the differential diagnosis.
A nationwide survey using questionnaires was performed on febrile illness cases with fever of unknown origin (FUO) experienced by 2843 pediatrics institutions with sick beds during a 5-year period before 2007. FUO was defined as a febrile illness of at least 2 weeks' duration with a temperature ≥ 38°C, and failure to establish a diagnosis in spite of intensive evaluation during seven days' hospitalization.
Two hundred fifty-five of 2843 questionnaire-surveyed institutions had 960 FUO cases, of which 132 could not be diagnosed, and 828 could be diagnosed after detailed medical examinations. The diagnoses they clarified included infectious diseases in 190 cases (23%), rheumatic diseases in 448 cases (54%), neoplasms in 67 cases (8%), and others in 123 cases (15%).
Clarification of illnesses that ought to be differentiated in the diagnostic approach to an FUO case is essential for arriving at its definitive diagnosis by exclusion.