Chronic Hepatitis B
Chronic carriers of the Hepatitis B virus have been defined as those who are Hepatitis B surface antigen positive for greater than 6 months.
These have generally been characterised as either healthy carriers who are anti-HBe positive with normal ALTs, or as patients with chronic Hepatitis B.
However it is clear that there is a variable course looking at clinical, biochemical and virological markers between these two case definitions.
Therefore it has been suggested that it may be more reasonable to classify chronically infected patients with Hepatitis B based on their serological and biochemical status.
† This would lead to three classifications, the first being patients who are e antigen positive with raised ALTs. These patients would also be Hepatitis B DNA positive and core antigen positive in the liver cells. These patients have ongoing active viral replication and evidence of liver damage due to Hepatitis B.
† A second classification would be patients who are e antigen negative, but have a raised ALT. These patients could be subdivided into two groups – one which has Hepatitis B DNA detectable as well as core antigen in liver.
Such patients may well be infected with the pre core mutant of Hepatitis B in which e antigen is not secreted but these patients do have detectable DNA suggesting that they have ongoing replication of this mutant Hepatitis B virus. There are other patients who are also e antigen negative, but have raised ALTs, but have no evidence of ongoing Hepatitis B replication in that they are DNA negative and have no core antigen in their liver.
It is important in this group to look for other causes of liver damage in a patient with chronic Hepatitis B surface antigenaemia.
Such patients may have ongoing liver damage due to superinfection with Hepatitis A, Hepatitis C or delta hepatitis.
They may also have liver damage due to other causes such as drugs or toxins such as alcohol.
† Finally the third group of patients are Hepatitis B e antigen negative, DNA negative, with no core antigen in their liver and normal ALTs.
These patients who are still surface antigen positive would fit the older definition of healthy carriers since they appear not to have any evidence of ongoing viral replication, nor is there evidence of other liver damage as characterised by raised ALT.