Hepatitis B is an inflammation of the liver caused by a virus. It is transmitted through contact with the blood or other bodily fluids of an infected person. Manifestations of the disease are highly variable, ranging from very mild forms that last only a few weeks to chronic forms with complications that can lead to cirrhosis or liver cancer. Hepatitis B tests can diagnose the presence of an acute or chronic liver infection, identify “healthy” carriers of the virus, detect all individuals who are protected by vaccination or a prior resolved hepatitis B infection, and much more.
The first tests used to diagnose the disease look for the hepatitis B surface antigen (HBsAg, or Australia antigen) in addition to antibodies produced by the body against this antigen (anti-HBs). Depending on the clinical situation, these tests will be followed by a measurement of HBeAg and anti-HBe antigen levels, associated with the patient’s infectiousness, or by a measurement of antibodies directed against a virus core particle (anti-HBc). In more complex cases, the total quantity of virus in the body (HBV DNA) can be measured. Refer to the sections concerning each of these tests.