Hepatitis B

Anyone at risk of hepatitis B infection should be offered a hepatitis B test, this includes:

  • Children born to mothers with HBV who are HBsAG positive
  • People from countries where hepatitis B is endemic (see map)
  • Family memebers of someone who is HBV positive
  • People involved in high risk sexual practices with a person who is could possibly be HBV positive
  • Men who have sex with men
  • Anyone who has ever injected drugs
  • Recipients of unscreened blood transfusion or blood products
  • People who may have had unsterile medical or dental procedures abroad
  • People who may have had ear piercing, body piercing, tattooing or acupuncture with unsterile equipment
  • Consider for any patient with abnormal liver function tests (LFT), especially elevated alanine aminotransferase (ALT)

**Sample required for diagnosis: a clotted blood (2-6ml) sample should be sent to Regional Virology laboratory at Royal Victoria Hospital Belfast, for HBV testing. If positive a second sample will be required for confirmation.

Rational for tests used to screen for HBV

Hepatitis B surface antigen (HBsAg) is a protein antigen produced by HBV. This antigen is the earliest indicator of acute hepatitis B and frequently identifies infected people before symptoms appear.

Hepatitis B surface antibody (anti-HBs). Its presence indicates previous exposure to HBV, but the virus is no longer present and the person cannot pass on the virus to others. The antibody also protects the body from future HBV infection. In addition to exposure to HBV, the antibodies can also be acquired from successful vaccination.

Hepatitis B e-antigen (HBeAg) is a viral protein associated with HBV infections. The e-antigen is found in the blood only when the virus is also present. HBeAg is often used as a marker of ability to spread the virus to other people (infectivity).

Anti-hepatitis B core antigen (anti-HBc) is an antibody to the hepatitis B core antigen. The core antigen is found on virus particles but disappears early in the course of infection. This antibody is produced during and after an acute HBV infection and is usually found in chronic HBV carriers as well as those who have cleared the virus, and usually persists for life.

HBV DNA is a more sensitive test than HBeAg for detecting viruses in the blood stream. It is usually used in conjunction with – rather than instead of – the regular serologic tests. It may be used to monitor antiviral therapy in patients with chronic HBV infections.