define hepatitis b
Definition. Hepatitis B is a potentially serious form of liver inflammation due to infection by the hepatitis B virus (HBV). It occurs in both rapidly developing (acute) and long-lasting (chronic) forms, and is one of the most common chronic infectious diseases worldwide. Contact with infected blood is a common means of transmitting hepatitis B. 2  One way this may happen is by being stuck with a needle. 3  Both health care workers and those who inject drugs into their veins are at risk in this way. 4  Having sex with a person infected by HBV is an important risk factor (especially anal sex).