The hepatitis B virus is one of the blood borne viruses (BBV) and can be transmitted through blood. However, the HBV virus is also present in other body fluids such as saliva, sperm, and vaginal fluids. Thus, these fluids too may become a source of infection, especially when they have been contaminated with minute amounts of blood (as is often the case with saliva).
The highest concentration of the virus appear in the blood. Some people may transmit the hepatitis B virus more easily than others, because they have larger amounts of the virus in their blood. Even a small amount of blood from someone infected by the virus can transmit the infection if it should enter your blood circulation, whether through an open wound, a cut or scratch, or a contaminated needle.
The virus can survive outside the body for at least one week. This means that objects and surfaces that have been contaminated with dried blood also constitute a risk.