Hepatitis B is a virus affecting the liver, which can cause scarring of the liver, liver failure, liver cancer and can be fatal.
Hepatitis B is spread by infected blood and other bodily fluids such as semen, vaginal secretions, saliva, open sores, and breast milk.
A person with hepatitis B may not know they've been infected, but symptoms can include feeling sick, lack of appetite, tiredness, aches and pains, headaches and yellowing of the skin and eyes, called jaundice.
A hepatitis B vaccine is available for travel to parts of the world where hepatitis is common, and for those in at-risk professions. It is now included in the routine vaccination programme for babies.
What happens to people with hepatitis B?
In most cases, hepatitis B causes limited infection. Usually people manage to fight off the infection successfully within a few months, developing an immunity that lasts a lifetime - this means you won't get the infection again. Blood tests show evidence of this immunity, but no signs of active infection.
However, some people don't get rid of the infection. If you are infected with hepatitis B for more than six months, you are considered a carrier, even if you have no symptoms. This means that you can transmit the disease to others through having unprotected sex, or sharing personal items such as toothbrushes or razors. Being a carrier also means that your liver may be more prone to injury.
For unknown reasons, the infection eventually goes away in a very small percentage of carriers. For others, the infection becomes chronic (long-term). Chronic hepatitis is an ongoing infection of the liver that can lead to cirrhosis. Cirrhosis causes liver tissue to scar and stop working.
If you are carrying the virus you should not donate blood, plasma, body organs, tissue, or sperm. Tell your doctor, dentist, and sexual partners that you are a hepatitis B carrier.
How common is hepatitis B?
The NHS says hepatitis B is not common with cases often confined to at-risk groups such as drug users, men who have sex with men and some ethnic communities (South Asian, African and Chinese).
How do I know if I have hepatitis B?
Symptoms of acute infection - when a person is first infected with hepatitis - include:
Often, symptoms occur one to six months after exposure. An estimated 30% of those infected do not show typical signs or symptoms.
How is hepatitis B diagnosed?
If your doctor suspects that you may have hepatitis B, he or she will arrange blood tests to look at the function of your liver. Hepatitis B is confirmed with blood tests that detect the hepatitis virus and various antibodies (infection-fighting cells) against the virus.
If your disease becomes chronic, a liver biopsy (tissue sample) may be needed to determine the severity of the disease.