About hepatitis B
A serious liver infection caused by the hepatitis B virus (HBV)
Hepatitis B is the world's most common serious liver infection, affecting nearly one-third of the world's total population. Over time, chronic (or long-term) hepatitis B can lead to severe liver damage in some people.
Hepatitis B infection is caused by a multiplying virus that attacks the liver. The hepatitis B virus (HBV), which is found in blood and infected bodily fluids, can be spread from a mother to her baby at birth. In fact, this is a common way that HBV is spread in many parts of the world. HBV can also be spread through unprotected sex and the sharing of unsterile needles or such personal care items as toothbrushes or razors.
A person who is initially infected with HBV is said to have an acute hepatitis B infection. Most people will recover fully. But others—especially infants and young children—may not be able to fight off the virus. When HBV stays in the blood for more than 6 months, it becomes a chronic infection. Chronic hepatitis B may last a lifetime. It may also lead to serious liver damage in some people.
Learn more about hepatitis B in the sections below.
Hepatitis B symptoms
Hepatitis B is known as a "silent" disease. This is because most people who are infected have no signs or symptoms—even though the hepatitis B virus may be multiplying in their body and damaging their liver for years.
Learn about hepatitis B symptoms 
How hepatitis B affects your liver
HBV lives mainly in the cells of your liver, where it multiplies and attacks healthy liver cells. Over time, this can lead to severe liver damage in some people.
Find out how hepatitis B affects your liver
Preventing the spread of the hepatitis B virus
HBV can be spread through blood and infected bodily fluids. If you have HBV, there are steps you can take to avoid spreading it to others.
Learn ways to protect others from HBV