The terminology associated with viral hepatitis is complex, but understanding some of the main terms used and the meaning of key test results will help to keep you informed about your condition.
Understanding the significance of antibodies and antigens is a good place to start.
An antigen is a foreign or invading protein substance that enters the body. Your body’s immune system defends against antigens by producing its own special proteins that bind to the invader to destroy them. These are antibodies, also known as immunoglobulin.
The production of antibodies against antigens is known as your ‘immune response’. Many of the following tests are used to measure your immune response.
Acute or chronic?
An acute illness means a short, sharp illness of sudden onset that may be severe, but most people recover within a few weeks without lasting effects. A chronic illness is one that lasts a long time (more than six months), possibly for the rest of a person’s life.
Hepatitis A (HAV)
This is a test to detect whether you have produced antibodies known as immunoglobulin M and immunoglobulin G against the hepatitis A virus (HAV). A total antibody test is able to indicate both current and previous infection with hepatitis A. It will also read positive after you have received the hepatitis A vaccination. It is presumed that one infection with hepatitis A produces lasting immunity (protection) against further infection.
Hepatitis B (HBV) – Antibody and antigen tests
Most people who come into contact with hepatitis B (HBV) will rid themselves or ‘clear’ the virus during the first six months of their infection. The disease is known during this phase as acute hepatitis B. People who do not clear the virus after six months will be diagnosed as having chronic hepatitis B.
Tests are carried out to look for antigens and antibodies in your blood. These are a sign or indication that:
- you have been infected by the virus in the past
- you have a new infection
- your infection is likely to go away by itself
- your infection has become chronic.
These antigens and antibodies are known as serological or viral ‘markers’. Medical staff will look for markers in your blood over the course of your infection to see how the virus is progressing and/or responding to treatment. In particular, finding the ‘surface’ and ‘e’ antigens known as HBsAg and HBeAg and their corresponding antibodies will be very important in establishing the pattern of your disease.
Hepatitis B surface antigen (HBsAg)
This is a test to find out if you have a current infection. HBsAg is the earliest sign of the virus and disappears from your blood as the infection clears. A positive result indicates infection. If the antigen is not found (negative result), this shows that either you have never been exposed to hepatitis B or that you have recovered from infection and rid yourself of the virus. The term
‘surface’ refers to the outer surface of the virus itself.
Hepatitis B surface antibody (Anti-HBs)
This is to detect the protective antibody in your blood that reveals whether you have had previous exposure to hepatitis B. The presence of the antibody anti-HBs (positive result) indicates that you are immune to hepatitis B due to vaccination or recovery from past infection, and are no longer infectious to others.
Hepatitis B e-antigen (HBeAg)
This test is used to confirm the presence of HBeAg, which only appears in the blood when the virus is present and is a sign that you are a ‘carrier’ (able to infect others). What happens after this antigen is found will depend on how quickly your immune system produces antibodies called anti-HBe. The appearance of an antibody and subsequent elimination of the virus to a very low level is known as ‘seroconversion’. The rate at which this occurs will vary from person to person and can take months or years. Although you remain infected, the virus is inactive and your liver is able to repair itself. This is known as an ‘inactive carrier state’.
Anti-HBe
This is the test that looks for the anti-HBe antibody produced in response to the hepatitis B e antigen (although anti-HBe is also present in people recovering from acute hepatitis B infection). In chronic hepatitis B, a positive result suggests that only low levels of the virus are likely to be present in your blood.
Anti-hepatitis B core antigen (anti-HBc)
The anti-hepatitis B core antigen is an antibody to the ‘core’ part of the hepatitis B virus, the hepatitis B core antigen. However, this antibody does not provide the protection usually associated with antibodies and is found in people with acute infection, in chronic carriers and in people who have cleared the infection. Doctors will use the results of other tests to interpret the presence of anti-HBc in your blood.
HBV DNA
This important test does not look for antigens or antibodies but monitors the success of antiviral medication. It shows the amount of virus in your blood, known as your ‘viral load’. The higher your viral load, the more active your infection will be. Active virus replication, where the virus is making lots of copies of itself, is known as positive HBV DNA. Doctors will be looking for a very low amount or no trace of the virus as a marker of your response to antiviral medication.
Hepatitis C (HCV)
As with hepatitis B, a number of tests will be carried out when you are suspected of having hepatitis C (HCV) or after the virus has been diagnosed. They will be used to follow its progression and to check on your response to treatment.
Anti-HCV
An anti-HCV test looks for any trace of antibodies in your blood. If they are found, this shows that you have been exposed to the hepatitis C virus. This test is unable to reveal whether you have an active viral infection.
HCV-RNA
An HCV-RNA test detects the hepatitis C virus in your blood and indicates whether this is an active infection. Evidence of HCV viral RNA is a ‘positive’ result while no sign will be ‘negative’. This test may also be used as a follow-up to your treatment to see if you have eliminated the virus from your body.
HCV Viral load (quantitative HCV)/PCR (polymerase chain reaction)
This test measures the number of viral RNA particles in your blood. Doctors will usually perform these tests over the course of your treatment. Measuring your viral load before and after treatment will show whether or not this therapy is working.
Viral genotyping
Viral genotyping is carried out to identify the types of hepatitis C virus. There are six major types, known as ‘genotypes’. The most common is genotype 1. Treatment time for genotype 1 is also the longest (48 weeks). Genotypes 2 and 3 have better success response rates to treatment (24 weeks therapy). Genotype tests are ordered before treatment is started to give doctors an idea of the length of time and the likely success of your therapy.
Some issues about testing
When testing for hepatitis B or C, there are some issues you may like to think about. Public knowledge about hepatitis is slowly improving but widespread ignorance about who gets hepatitis and how it is transmitted remains. It is a good idea to discuss your concerns with a health professional or counsellor who is trained to help you cope with hepatitis and any
social difficulties that come with it, such as:
Most insurance companies will ask applicants if they have been tested for HIV, hepatitis B and hepatitis C. A positive test result may mean a life insurance policy or a mortgage linked to a life policy could be refused or the premium raised. If this happens, it is worth talking to your doctor as many consultants are willing to write to a mortgage or insurance company stating your health and life expectancy.
This is often a difficult decision but consider that a positive result may affect your family and sexual partner(s) and whether these people should also think about testing. If you are HBsAg positive your partner will need vaccinating if they are negative.
You may want only certain people to know about your test and results. Certain agencies such as GUM (genito-urinary medicine) clinics offer a confidential testing service, although in the case of a positive result your GP will become involved when you are referred to a specialist for on-going care.