The field of clinical virology continues to make rapid progress and the developments in molecular biological techniques are leading to improved methods of diagnosis and an increased understanding of viral pathogenesis. This revised textbook on the field includes new material on on hepatitis A and E as well as individual contributions on hepatitis B, D and C. The chapters on viral haemorrhagic fevers have been expanded and the herpes simplex virus chapter contains a section on human herpes virus 7. The rapid developments in the field of human retroviruses and prion diseases have also been extensively covered to reflect the increase in knowledge of the virus groups covered in the various chapters.