Fever of Unknown Origin in Children

Fever is one of the more common symptoms that prompts families to seek medical advice, even though fever itself is not a disease and usually spontaneously recedes when the causative illness is cured. However, if a fever of more than 38.5 degrees C remains for longer than 8 days without an etiology being established, despite an extensive medical history and a careful physical examination, we speak of "fever of unknown origin" (FUO). To further evaluate an FUO, repeated medical history and physical examinations are usually necessary. If there is further ambiguity, the diagnosis should be expanded, first with simple orientation followed by more focused and specific laboratory studies and radiological procedures. With this approach, it has become increasingly easy to shift more clinical cases of FUO towards a final diagnosis of a verifiably infectious, autoimmune or malignant illness, leaving a group of only 10-30% of all formerly undiagnosable cases as FUO. It is hoped that by introducing even more disease prevention vaccines into public vaccination programs, in addition to incorporating more focused and sophisticated laboratory and imaging studies, that the necessity of diagnosing an FUO can be reduced even further. With these improved measures, it should even be easier to treat rare and serious diseases, such as infectious endocarditis, promptly and correctly.