In this article we will discuss about the Pyrexia of Unknown Origin (PUO):- 1. Causes of PUO 2. Infection of PUO 3. Laboratory Diagnosis. Causes of PUO: The most common causes of prolonged PUO are: (a) Chronic infections; (b) Tumours, (c) Connective tissue disorders; (d) Granulomatous diseases (e) Drug hypersensitivity reactions (Table 94.1): Infection of […]