Hepatitis C Tests PCR

Polymerase Chain Reaction is a very sensitive way of looking for a virus. It actually only detects a very small piece of the virus. It takes many steps and is therefore still an expensive test. To save healthcare dollars, these tests should only be done for the right reasons.

Genotyping tells you what kind of hepatitis C you have. It turns out that there are quite a few different families of hepatitis C. Overall, the different genotypes behave similarly in how quickly they damage your liver. The exception may be genotype 3 viruses as they also cause fat to deposit in the liver. The different genotypes respond a little bit differently to the currently available treatment, Pegylated Interferon and Ribavirin. Click on the genotypes listed below to find out more about the different types of hepatitis C virus:

 

  • Genotype 1
  • Genotype 2
  • Genotype 3
  • Genotype 4
  • Genotype 5 is very rare in North America but is seen in people from Africa. We do not have a lot of experience in treating these patients.
  • Genotype 6 is also rare in North America but found in Asia. We also do no not have a lot of experience in treating these patients.

All the above cure rates are what we see in people without cirrhosis and without other conditions such as HIV infection. In people with cirrhosis, the cure rates are generally lower by as much as 50%

HCV PCR is reported as a viral load, ie how much virus is around. Previously, we had two different PCR tests. The Quantitative test could give us a viral load but values under 600 IU/mL were undetectable or negative. The Qualitative test did not give a viral load but it could tell if HCV was present, so long as the viral load was over 50 IU/mL. Since early 2008, Ontario has replaced these two tests with a single better test that can measure HCV viral load down to 15 IU/mL. This test should be done in the following circumstances:

  • Pre-treatment viral load: In most people, the viral load is stable over time and runs between 1.00E5 IU/mL (one hundred thousand) and 1.00E7 IU/mL (ten million). Those with high viral loads may be less likely to respond to currently available therapy. However, a high viral load was defined using the older test, and it is not perfectly clear yet exactly what viral load is high using this new test.
  • Rapid Virological Response: Viral load after 4 weeks of therapy (just before the 5th shot) has fallen dramatically, under 50 IU/mL. These individuals are very sensitive to interferon and ribavirin therapy and are likely to respond, even if the duration of treatment was shortened.
  • Early Virological Response: Viral load after 12 weeks therapy (just before 13th shot) has fallen by at least 100-fold (also known as a 2-log drop) or if the viral load remains over 6.00E4 IU/mL (sixty thousand), then ongoing treatment is very unlikely to work - treatment should be stopped. These individuals just don't respond to interferon and ribavirin therapy (non-responders).
    • Complete Early Virological Response: Viral load after 12 weeks of therapy is less than 600 IU/mL. These individuals still have a very good chance (around 80%) of responding to interferon and ribavirin therapy if they can finish the entire course of treatment, usually 48 weeks.
    • Partial Early Virological Response: Viral load after 12 weeks of therapy is over 600 IU/mL but has fallen by at least 100-fold since starting treatment. These individuals have a small chance (around 20-30%) of responding to interferon and ribavirin thearpy even if they finish 48 weeks treatment. There are some suggestings that prolonging treatment to 72 weeks can increase the chances of response to about 50%. However, if HCV virus is still detectable after 24 weeks of treatment, then the treatment is unlikely to work and should be stopped.
  • End of Treatment viral load: If the HCV virus is still detectable, even at low levels, at the end of treatment, then treatment has failed. It is not crucial to know this result if the treatment worked. However, if treatment failed, it is likely very important to know this result as it will help in choosing future treatment options.
  • Sustained Virological Response: If the HCV virus remains undetectable 6 months or more after stopping treatment, then the hepatitis C infection has likely been cured. This means that:
    • The infection is unlikely to return. If the liver had already been severely damaged to the point of cirrhosis, liver failure is unlikely but liver cancer can still happen - ultrasound should still be done every 6 months to look for early cancer.
    • The antibody test (anti-HCV) will likely remain positive. However, this is because the body's immune system remembers the hepatitis C infection from the past, and it does not mean that the infection is still there. Despite the antibody, you are not immune and can be re-infected if you are exposed to hepatitis C again