The virus of hepatitis B propagates when the blood or corporal fluids of an infected person enters in the body of a noninfected person. It has been proved that blood; saliva, semen and vaginal secretions are infectious. Four ways of transmission have been identified: vertical, domiciliary contacts, sexual (horizontal), or by injections or wounds from contaminated equipment; blood transfusions, or treatment with blood derivatives. To prevent virus transmission, preventive universal measures and vaccination are used.

hepatitis B; transmission; prevention; vaccination