Hepatitis B virus (Hepadnavirus)
The hepatitis B virus is a member of the hepadnavirus family, which are small virions 42 nm in diameter. Its name reflects the fact that it infects the liver (“hepar” in Greek) causing an inflammation called hepatitis. These DNA viruses are enveloped with a capsid1 of icosahedral symmetry2.
The virus is most often transmitted by contact with blood, for example
- when sharing a needle, syringe or drug preparation equipment or
- during accidental needle sticks in the workplace .
The hepatitis B virus can also be transmitted during sexual intercourse and during childbirth from mother to child. Hepatitis B is mainly present in Africa (6%) and Southeast Asia (2% to 3%).
Cirrhosis and cancer
Hepatitis B is an infection that affects the liver causing inflammation of the liver (acute or chronic hepatitis). The infection can be perfectly asymptomatic initially or more rarely manifest itself in jaundice with fatigue and nausea. Chronic inflammation of the liver can lead to cirrhosis3 and even liver cancer, which is why diagnosis and treatment are important.
The risk of developing chronic hepatitis depends on your age. Thus according to the WHO, 80% to 90% of infants infected during the first year of life develop chronic infections, while 0% to 50% of children infected before the age of 6 years and less than 5% of adults will develop chronic hepatitis.
Prevention among intravenous drug addicts (reducing needle exchange) has reduced the transmission of hepatitis B and also of hepatitis C and HIV, which are transmitted in the same way. The safe and effective hepatitis B vaccine offers more than 95% protection. The vaccine prevents not only the infection but also the development of long-term complications including cirrhosis and liver cancer.