Hepatitis C Virus Antibodies

Each of the most common tests have a slightly different purpose:   

• Anti-HCV Antibody test detect the presence of antibodies to the virus. These are substances produced by the body when it encounters the virus , so a positive results shows that you have been exposed to HCV. These tests on their own may not be able to tell if you still have an active viral infection, only that you were exposed to the virus in the past. Usually, the test is reported as “positive” or “negative.” There is some evidence that, if your test is “weakly positive,” it may not mean that you have been exposed to the HCV virus. All positive results (weak or strong) will either be repeated using a second antibody test or most likely using the test for the virus genetic material , the viral load test (described below).
• Viral Load or Quantitative HCV tests measure the number of viral particles in your blood. Viral load tests are used before treatment to help determine how long treatment needs to be given (along with other factors, such as your age, gender, the changes seen in a liver biopsy, and genotype, discussed below). It is also used to follow response to treatment by comparing the amount of virus before, during and after treatment at time points dependant on what type and length of treatment is given. The aim is to get the levels of virus to undetectable/not detected.
• Viral genotyping is used to determine the genotype (‘strain’), of the virus present. There are 6 major types of HCV. Genotypes 1, 2 and 3 are found across the world and genotype 1 is the most common. It can be important to know the virus genotype to help doctors decide on the treatment plan. The antiviral drugs which are now used are called direct acting antivirals (DAAs) and they are effective against all genotypes of HCV and this treatment is successful in 90% of patients .

Hepatitis C infection is a common cause of chronic liver disease . About 65-75% of those infected will develop chronic hepatitis, and about 20-30% of those develop cirrhosis. HCV testing is recommended in the following cases: 

• If you have ever injected illegal drugs 
• If you received a blood transfusion or organ transplantation before mid-1992* 
• If you have received clotting factor concentrates produced before 1987 
• If you were ever on long-term dialysis 
• For children born to HCV-positive women 
• For health care, emergency medicine, and public safety workers after needlesticks, sharps, or mucosal exposure to HCV-positive blood 
• For people with evidence of chronic liver disease

* The blood supply has been monitored in the UK since mid-1992, and any units of blood that test positive for HCV are rejected for use in another person. The current risk of HCV infection from transfused blood is less than 1 case per million transfused units.

A positive anti-HCV test will be confirmed with an alternative test, especially if the test is “weakly positive.” HCV viral load and genotyping will be performed to plan treatment and to monitor response to treatment.

If the antibody test result is positive, you have probably been infected with hepatitis C, even if it was so mild you did not realise you had it.

A repeat antibody test will usually be requested, followed by a viral load test.

A positive (or detectable) HCV RNA means that you are currently infected by HCV.

If no HCV viral particles are detected then the person either does not have an active infection or the virus is present in very low numbers.

HCV antibodies usually do not appear until several months into an infection but will always be present in the later stages of the disease.

Ten percent of people with HCV have no recognised source for their infection. Sexual exposures account for 15% of HCV cases.

Hepatitis C often leads to chronic hepatitis, which can progress to cirrhosis and liver cancer (hepatocellular carcinoma). Early detection of the virus can alert your doctor to follow your liver function more closely than usual and to consider treating you if you are chronically infected.