Hepatitis B is a liver infection caused by the hepatitis B virus (HBV). It is one of several various causes of hepatitis, a condition characterized by inflammation and enlargement of the liver. Other causes of hepatitis include, for example, certain drugs, inherited disorders, and autoimmune diseases. HBV is one of five "hepatitis viruses" known to cause disease in humans . The other four are A, C, D, and E.
The course of HBV...
Hepatitis B is a liver infection caused by the hepatitis B virus (HBV). It is one of several various causes of hepatitis, a condition characterized by inflammation and enlargement of the liver. Other causes of hepatitis include, for example, certain drugs, inherited disorders, and autoimmune diseases. HBV is one of five "hepatitis viruses" known to cause disease in humans . The other four are A, C, D, and E.
The course of HBV infections can vary from a mild form (acute) that lasts only a few weeks to a more serious, chronic form lasting years. Sometimes chronic HBV leads to serious complications such as cirrhosis or liver cancer.
HBV is spread through contact with blood or other body fluids from an infected person. Exposure can occur, for example, through sharing of needles for IV drug use or through unprotected sex. People who live in or travel to areas of the world where hepatitis B cases are high are at a greater risk. Mothers can pass the infection to their babies, usually during or after birth. The virus, however, is not spread through food or water, casual contact such as holding hands, or coughing or sneezing.
Some of the various stages or forms of hepatitis B include:
- Acute infection
- People recently infected with HBV with a positive screening test. Some people have typical signs and symptoms including high temperature tiredness, pain in their right side and jaundice, but some people do not feel ill at all
- Chronic infection
- People who are known to have been infected for more than 6 months with the virus detected by laboratory tests accompanied by inflammation of the liver
- Carrier (inactive) state
- persistent infection but no signs of liver inflammation. A carrier may appear to be in good health but they still have the virus and can potentially infect others
- "Cleared" infection
- no longer any evidence of infection; viral antigen and DNA tests are negative and no signs or symptoms of liver inflammation (although, in many cases, the virus is present in an inactive state in the liver)
There are several different tests that can be used to detect current or previous HBV infection. Some of the tests detect antibodies produced in response to exposure to the HBV; some detect viral antigens (part of the virus itself) while others detect viral DNA. They can be used to screen for infection in the absence of symptoms, to determine whether infection is acute or chronic, or to monitor a chronic infection.