Hepatitis B is inflammation (irritation and swelling) of the liver due to the hepatitis B virus (HBV).

Other types of hepatitis include:

• Hepatitis A
• Hepatitis C
• Hepatitis D

See also:

• Autoimmune hepatitis
• Chronic persistent hepatitis
• Drug-induced hepatitis

The hepatitis B virus spreads through blood and other body fluids. Infection can occur if you have:

• Blood transfusions
• Contact with blood in healthcare settings
• Received a tattoo or acupuncture with contaminated instruments
• Shared needles during drug use
• Unsafe sex with an infected person

The hepatitis B virus can be passed to an infant during childbirth or shortly thereafter if the mother is infected.

The risk of becoming chronically infected depends on your age at the time of infection. Most newborns and about 50% of children infected with hepatitis B develop chronic hepatitis. Only a few adults infected with HBV develop the chronic condition.

Most of the damage from hepatitis B virus is due to by the body's response to the infection. When the body's immune system detects the infection, it sends out special cells to fight it off. However, these disease-fighting cells can lead to liver inflammation. The liver damage also interferes with the body's ability to get rid of bilirubin, a breakdown product of old red blood cells). This leads to jaundice (yellow discoloration of the eyes and body) and dark urine.

It takes about 1-6 months from the time of infection until symptoms of acute hepatitis appear. Early symptoms may include:

• Appetite loss
• Fatigue
• Low-grade fever
• Muscle and joint aches
• Nausea and vomiting
• Yellow skin and dark urine due to jaundice

The following tests are done to help diagnose hepatitis B:

• Albumin level (may be low)
• Hepatitis B antibody panel
• Liver function tests
• Prothrombin time (may be increased due to severe liver failure)