Everything you need to know about hepatitis B
Learn more about what it is, the symptoms and how it's diagnosed.
What is hepatitis B?
Hepatitis B is caused by the hepatitis B virus (HBV) and is transmitted through contact with infectious body fluids of an infected individual, such as blood, semen or vaginal secretions. The virus can be passed from an infected pregnant woman to their baby and spread by having unprotected sex with an infected partner. If an adult is infected with the hepatitis B virus, usually they can fight it off and recover within a couple of months. However, if a child is infected, they usually develop a long-term infection - chronic hepatitis B, which can eventually lead to scarring of the liver and liver cancer. For the hepatitis B virus, antiviral medication is available. A vaccination against hepatitis B is also available and is offered to those who are at risk of being exposed to the virus. The hepatitis B vaccine is included in the routine immunisation programme in the UK to allow all children to benefit from the viral protection.
What are the symptoms of hepatitis B?
Many of those with hepatitis B won't experience any symptoms and may fight off the virus without realising they were infected.
If symptoms do develop they may include the following:
Yellowing of the eyes and skin (jaundice)
- Flu-like symptoms
- Pale stools
- Dark urine
- Unexplained weight loss
- Joint and muscle pains
- Abdominal pain
- Loss of appetite
If symptoms do develop, they tend to occur a couple of months after exposure to the hepatitis B virus.
How is hepatitis B diagnosed?
With hepatitis viruses which can cause a long-term infection, such as hepatitis B or C, a blood test looking for proteins from the surface of the virus can be useful, as can looking for the virus’ DNA.
Also, because many people have been immunised against hepatitis B, it is important to be able to differentiate between a previous infection from current infection.
- Hepatitis B surface antigen (HBsAg) - A positive result for the HBsAg antigen shows a person is infected with the hepatitis B virus and can spread the virus to others through their blood. Testing for the HBsAg antigen alone is not enough to determine if the infection is acute or chronic.
- Hepatitis B surface antibody (HBsAb) - A positive result for the HBsAb antibody shows a person is protected/immune against the hepatitis B virus and therefore unable to spread the virus to others. This protection may be the result of the hepatitis B vaccine or a successful recovery from a past hepatitis B infection. This test is not routinely included in blood bank screenings.
- Hepatitis B core antibody (HBcAb) - A positive result for the HBcAb antibody shows a past or current hepatitis B infection. Unlike a positive result for the HBsAb antibody, the hepatitis B core antibody does not provide protection against the hepatitis B virus. But without testing for both the HBsAg and anti-HBs, the positive HBaAb result cannot be fully understood.