HEPATITIS B VIRUS

Hepatitis B is a potentially fatal liver disease caused by the hepatitis B virus (HBV).  Worldwide, 350 million people are chronically infected with HBV and one third of the world’s population have been exposed at some point in their lives.  Each year, hepatitis B kills between 500,000 and 1 million people, and is second only to tobacco as a human carcinogen, causing 50% of all liver cancers worldwide.

It can be transmitted in a variety of ways and is thought to be 100 times more infectious than HIV.  It is found in blood and other bodily fluids.  The most common route of infection is between mother and baby at birth, although this is prevented in the UK through vaccination of babies born to infected mothers.  Most infections in Europe and North America arise through sexual contact and injecting drug use.  Tattooing, piercing and needle-stick injuries are other means of transmission.

Chronic hepatitis B is not a notifiable disease in the UK and calculations of prevalence are therefore uncertain.  The Department of Health estimates that 180,000 people (0.3% of the population) are chronically infected in the UK, with approximately 7,700 new cases of chronic disease per annum.  Almost all of these are imported via immigration from countries with a high prevalence of HBV, generally from mother to child transmission.

A safe and effective vaccine against HBV infection has been available since 1982 and more than 1 billion people have been vaccinated worldwide.  Around 150 countries have plans or strategies implemented to vaccine newborns or adolescents.  The UK, however, is not one of them.  The low reported incidence to date has led successive Governments to believe that universal vaccination at birth or in childhood would not be cost effective.  Identified high-risk groups are offered vaccination in the UK but uptake is poor.

A range of treatments for chronic HBV exist using interferon, lamivudine and, more recently, adefovir dipivoxil, which appears not to generate intolerable side effects or resistance in the short term.  Promising future therapies are under development.