Hepatitis C (cont.)

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What is hepatitis C infection?

Hepatitis C infection is an infection of the liver caused by the hepatitis C virus (HCV). It is difficult for the human immune system to eliminate hepatitis C from the body, and infection with hep C usually becomes chronic. Over decades, chronic infection with hepatitis C damages the liver and can cause liver failure. In the U.S., the number of new cases of hepatitis C infection has declined from a peak of 200,000 annually to about 17,000 in 2007. When the virus first enters the body, however, there usually are no symptoms, so these numbers are estimates. Up to 85% of newly-infected people fail to eliminate the virus and become chronically infected. In the U.S., more than three million people are chronically infected with hepatitis C. Infection is most commonly detected among people who are 40 to 60 years of age, reflecting the high rates of infection in the 1970s and 1980s. There are 8,000 to 10,000 deaths each year in the US related to hepatitis C infection. Hepatitis C infection is the leading cause of liver transplantation in the US and is a risk factor for liver cancer.

What is the nature (biology) of the hepatitis C virus?

'Hepatitis' means inflammation of the liver. Hepatitis C is one of several viruses that can cause hepatitis. It is unrelated to the other common hepatitis viruses (for example, hepatitis A or hepatitis B). Hepatitis C is a member of the Flaviviridae family of viruses. Other members of this family of viruses include those that cause yellow fever and dengue.

Viruses belonging to this family all have ribonucleic acid (RNA) as their genetic material. All hepatitis C viruses are made up of an outer coat (envelope) and contain enzymes and proteins that allow the virus to reproduce within the cells of the body, in particular, the cells of the liver. Although this basic structure is common to all hepatitis C viruses, there are at least six distinctly different strains of the virus which have different genetic profiles (genotypes 1 to 6). In the U. S., genotype 1 is the most common form of hepatitis C. Even within a single genotype there may be some variations (genotype 1a and 1b, for example). Genotyping is important to guide treatment because some viral genotypes respond better to therapy than others. The genetic diversity of hepatitis C is one reason that it has been difficult to develop an effective vaccine since the vaccine must protect against all genotypes.

How does liver damage occur in hepatitis C infection?

The presence of hepatitis C in the liver triggers the human immune system, which leads to inflammation. Over time (usually decades), prolonged inflammation may cause scarring. Extensive scarring in the liver is called cirrhosis. When the liver becomes cirrhotic, it fails to perform its normal functions, (liver failure), and this leads to serious complications and even death. Cirrhotic livers also are more prone to become cancerous.

Medically Reviewed by a Doctor on 5/26/2015

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