ABSTRACT
Introduction and epidemiology Hepatitis B is a DNA virus with particular affinity for replicating within hepatic tissue. It is the most infections virus likely to be met in common clinical practice, with significant morbidity and mortality on a global basis. The likelihood of transmission is dependent on virus infectivity, viral load and host factors, particularly underlying immunity. It is most likely to be spread by the parenteral route, but sexual activity and close social contact are also important mechanisms. Mother-to-child transmission, particularly during parturition and breast feeding, are well recognized. A recent study estimated that about 18% of acute hepatitis B infections in the UK were from sexual transmission. In countries of medium or higher prevalence, this figure is likely to be higher.
