Hepatitis B is the most common liver infection in the world and is caused by the hepatitis B virus. The hepatitis B virus enters the body and travels to the liver via the bloodstream. In the liver, the virus attaches to healthy liver cells and multiplies. This replication of the virus then triggers a response from the body’s immune system. People are often unaware they have been infected with the hepatitis B at this stage.
The liver is the main site of hepatitis B viral multiplication. Hepatitis B infection can lead to cirrhosis (scarring of the liver), liver cancer or liver failure if it is not diagnosed and managed.
Worldwide, 240 million people have been infected with hepatitis B and about 780,000 people die every year due to the consequences of hepatitis B. Hepatitis B prevalence is highest in sub-Saharan Africa and East Asia. Most people in these regions become infected with the hepatitis B virus during childhood (WHO Hepatitis B Fact Sheet).
High rates of chronic infections are also found in the Amazon and the southern parts of Eastern and Central Europe. In the Middle East and the Indian sub-continent, an estimated 2–5% of the general population is chronically infected (WHO Hepatitis B Fact Sheet). Other groups at higher risk of hepatitis B infection include Indigenous Australians, people participating in high risk sexual activity and people who inject drugs (O’Sullivan, B.G., et al; 2004).
In Australia, 213,300 people are chronically infected with hepatitis B (Kirby Institute, Annual Surveillance Report (ASR) 2015-p12). However, nearly half of those living with chronic hepatitis B in Australia are undiagnosed (WHO Regional Reference Laboratory for Hepatitis B).
Deaths from primary liver cancer are climbing faster than any other cause of cancer death in Australia and untreated chronic hepatitis B is a major contributor (National Liver Cancer Prevention Policy, 2012). Most people diagnosed with liver cancer in Australia die within one to two years – many in the first month after diagnosis.
Hepatitis B infection is considered to be ’acute‘ during the first 6 months after infection. If hepatitis B virus tests (HBsAg+) are positive after 6 months, then a person is considered to have ’chronic‘ (long term) hepatitis B infection which can last a lifetime.
Please click here to watch an interview with Professor Narci Teoh explaining what you need to know about hepatitis B. The video is also available in Chinese Mandarin. (Filmed 17 July 2013).