Genotypes of hepatitis C virus infection

Six major strains (genotypes) of the hepatitis C virus (HCV) cause infection. You may be infected with more than one genotype at a time.

  • Genotype 1 is the most common strain in the United States.
  • Genotypes 1, 2, and 3 are found worldwide.
  • Genotype 4 is found throughout northern Africa.
  • Genotype 5 commonly is found in South Africa.
  • Genotype 6 is common in Asia.

Genotype testing is done with a blood test.

How genotype affects treatment

Although genotype tests are not used to diagnose HCV infection, they may be done before treatment begins. Knowing the genotype may help a doctor choose the best treatment plan. You should know your genotype before treatment starts.

Antiviral medicines are more likely to work for people who have genotype 2 or 3.

If blood tests show that you have responded to antiviral therapy (the virus is not detected in your blood) after 6 months, treatment may be:

  • Continued for another 6 months, if you are infected with genotype 1.
  • Stopped, if you are infected with genotype 2 or 3. Prolonging treatment does not seem to provide any additional benefit.

The genotype of HCV does not appear to have any effect on the severity of HCV infection or to affect your risk of developing cancer of the liver (hepatocellular carcinoma).

Last Updated: July 13, 2009

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