Undiagnosed undifferentiated fever in Far North Queensland, Australia: a retrospective study

• Aetiologies of fever in far north Queensland Australia are described.
• More than half of acute undifferentiated fevers are undiagnosed.
• A robust definition of undiagnosed undifferentiated fever is proposed.
• A broad-diagnostic approach is suggested to determine pathogen causing fever.

SummaryObjectivesThis study aimed to describe the causes of acute undifferentiated fever (AUF) and to develop a robust definition of undiagnosed undifferentiated fever (UUDF).MethodsThis was a retrospective study of AUF over 3 years (2008–2011) in an Australian tertiary hospital. Request for laboratory investigation of one or more infectious agents was used as the search tool.ResultsA total of 340 patients with AUF, aged 15–65 years, were identified over the study period. A final diagnosis was made in 147 (43.2%) patients, dengue fever being the most frequent. The aetiology of fever was not determined in 193 (56.8%) patients. Elevations of C-reactive protein (CRP) and hepatic aminotransferase levels were common in these patients; two patients died. The characteristics of UUDF were fever for ≤21 days and failure to reach a diagnosis after clinical evaluation and specific laboratory investigations.ConclusionThe high burden of UUDF argues for a better diagnostic approach to fever that is capable of identifying a broad range of infectious agents.