Hepatitis B is an infection of the liver caused by the hepatitis B virus. It can cause inflammation (swelling) of the liver, and sometimes significant liver damage.
The Hepatitis B virus is present in body fluids such as blood, saliva, semen and vaginal fluid. It can be passed from person to person through unprotected sex (without using a condom) or by sharing needles to inject drugs, for example.
Infected mothers can also pass the virus to their baby during childbirth, often without knowing they are infected.
Not everyone with Hepatitis B knows that they've been infected, so the virus can be picked up and passed very easily.
Tests and treatment
Hepatitis B is diagnosed through specific blood tests. The incubation period (the time it takes from coming into contact with the virus to developing infection) is between one and six months, so tests may need to be repeated over a period of time.
If you're diagnosed as having a Hepatitis B infection, you will be advised to have regular blood tests and physical check-ups.
The vast majority of people who are infected with Hepatitis B are able to fight off the virus and fully recover from the infection within a couple of months.
If you have acute (short-term) Hepatitis B, there is usually no specific treatment. You may be offered painkillers for your symptoms and advised to rest, eat healthily and avoid alcohol.
Most people tend to be free of symptoms and recover completely within a couple of months, never going on to develop chronic (long-term) hepatitis.
However, in some people, the Hepatitis B virus will go on to cause a chronic (long-term) illness, where it lasts for longer than six months.
Without treatment, about a third of people with chronic hepatitis B infection go on to develop a disease of the liver, which can be very serious. There are two types of treatment for chronic (long-term) Hepatitis B infection - interferon and antiviral drugs.
A course of vaccinations is available to protect against hepatitis B. This is available for people who have a higher risk of coming in to contact with the virus, including:
babies born to infected mothers
close family and friends of infected people
people travelling to high-risk countries
injecting drug users
people who change their sexual partners frequently or men who have sex with men
people whose work places them at risk, such as nurses, prison wardens, doctors, dentists and laboratory staff
Ask your GP or visit any sexual health or GUM (genito-urinary medicine) clinic for the hepatitis B vaccination.
For full protection, you will need three injections of hepatitis B vaccine over a period of four to six months.
A blood test is then taken one month after the third dose, to check that the vaccinations have worked.