An Infectious Disease (ID) physician plays a key role in diagnosing the cause of a Fever of Unknown Origin (FUO), a condition defined by a fever of at least 38.3°C (101°F) lasting for more than three weeks, without an identifiable diagnosis despite initial investigations.
The ID physician's approach begins with a thorough history and physical examination to identify possible clues, such as travel history, exposure risks, underlying medical conditions, and recent procedures or infections. They carefully review symptoms to differentiate between infectious, autoimmune, and malignancy-related causes.
Next, a structured diagnostic work-up is initiated. The ID specialist typically orders a broad range of laboratory tests and Imaging studies such as chest X-rays, CT scans, or ultrasounds may be employed to identify abscesses, lymphadenopathy, or other abnormalities.
If initial testing yields no results, the ID physician may narrow down the differential diagnosis by considering rarer infections, such as tropical diseases, or reviewing the possibility of non-infectious conditions like malignancy or inflammatory disorders. Depending on the patient's condition, empirical treatment may be initiated while awaiting diagnostic confirmation.
Throughout the work-up, the ID physician collaborates with other specialists and continues to reassess the patient’s condition, often requiring multiple rounds of testing and follow-up to pinpoint the underlying cause of the fever.
