Fever of unknown origin, a literature survey.

This review summarizes the different causes of fever of unknown origin reported in the internationally indexed literature from 1961 till 1990. In 1961 Petersdorf published his landmark report that, for the first time, proposed criteria that cases have to meet to be considered as fever of unknown origin. We only retained cases and series that met these criteria. We meticulously compared the reported case series and tried to explain the differences between these series.