Undifferentiated febrile illnesses in military personnel

Undifferentiated febrile illnesses (UFIs) present with acute symptoms, objective fever and no specific organ focus on clinical assessment. The term is mostly used in developing and tropical countries where a wide range of infections may be responsible. Laboratory diagnosis often requires specialist microbiology investigations that are not widely available, and serology tests that only become positive during convalescence. Optimal clinical management requires a good travel history, awareness of local endemic diseases, an understanding of the features that may help distinguish different causes and appropriate use of empirical antibiotics. This review describes the most common examples of UFI in military personnel on overseas deployments, and provides a practical approach to their initial management.