Hepatitis B, one of the major epidemic viruses in history.


Hepatitis B virus (HBV) is almsot 100 times more infectious than HIV, although they share the same passage for transmission. Almost a tenth of chronic hepatitis patients infected with HBV in the early stage of life are at a great risk of developing liver cirrhosis or cancer, which is the third largest cause of death by cancer in men, worldwide.

About 2 billion people in the world have been infected by Hepatitis B virus (HBV), of which at least 350 million have developed chronic hepatitis B infection. These chronic patients are at a high risk of developing cirrhosis and liver cancer, and death. A million people die of liver failures caused by HBV in the world each year. Fortunately, HBV vaccine has been available since 1982, and the number of HBV infections is decreasing. HBV vaccine is 95% effective in the prevention of HBV infection, while it is not a cure for chronic hepatitis.

The most common traditional form of HBV infection is "perinatal", i.e. infection at the time of birth and afterwards, from mother to child. HBV is also commonly transmitted among children, and through unsafe injections and blood transfusion, and sexual contact. After the introduction of vaccine, and in the industrial countries, infection through sexual contact and blood transfusion prevails over perinatal infection. HBV is not transmitted by casual contacts, or contaminated food and water. Childhood infection of HBV has been almost eliminated after the introduction of the HBV vaccine. About 90% of infants infected in the first year after birth, and 30-50% of children infected during 1-4 year period develop chronic infection. For these people who became chronically infected in young ages, the likelihood for developing liver cirrhosis or cancer is 25%.

Chronic hepatitis is often treated with interferon and a drug lamivudine, which is not always effective and costs very high. Another option for the patients with liver cirrhosis is liver transplantation, which is also costly and not usually successful. Liver cancer is almost always fatal, and develops in 35-65 years of age. Most of liver cancer patients die within months of diagosis. With chemotherapy and liver transplant surgery may extend life up to a few years.