Possible causes of Pyrexia of Unknown origin (PUO)

 " IMAGINE "

• Infections:        
•  Malignancy
• Automimmune Diseases
• Granulomas (Sarcoidosis, Crohn's disease)
• Iatrogenic (Drug fever, Thrombophlebitis)
• Nurses, Doctors and all paramedical staff: factitious fever
• Etc

Infections can be any. Some of the common presentations are:

• Bacterial: TB, Typhoid, Bacillary endocarditis and septicemia, Abscess (subphrenic, intrahepatic etc)                    
• Viral: Hep B, Protozoal:malaria, amoebiasis, spirochaetes