Hepatitis B virus belongs to the family Hepadnaviridae and can cause acute infectious hepatitis, as well as chronic hepatitis.
Chronic hepatitis develops in 15% of those who have been infected with hepatitis B virus. Sources of infection are patients with acute and chronic forms of hepatitis B, as well as virus carriers.
Virus transmission results from contact with infected blood and other body fluids, such as sperm and vaginal secretions.
Most common forms of virus transmission are: blood transfusions, unprotected sexual intercourse, contaminated needles and syringes. Another important form of virus transmission is vertical transmission - from mother to child during childbirth.