Epidemiology and etiology Categories of Illness Causing PUo Infections 30-40% Malignancies 20-25% Collagen Vascular disease 25-30% Undiagnosed 10-15%Epidemiology and Etiology Infections 30 - 40 % Malignancies 20 – 25 % Collagen Vascular Disease 25 – 30 % Undiagnosed 10 – 15 % Categories of Illness Causing PUO