How does hepatitis b spread?

Many ways: Blood transfusion, sex, intravenous drug use with infected needle, post exposure needle stick ( needle that was used for injecting some one who is infected with hepatitis b), although not all needle sticks will result into an infection.

Hepatitis B: Hepatitis B is spread by fluids like blood or semen. It can be spread by sexual contact with someone who is infected or by sharing needles or syringes. It can be spread from mother to baby when giving birth. Healthcare workers can become infected by a needle stick. It could even be spread by sharing a razor or toothbrush with someone who is infected.