- Hepatitis C (hep C, HCV) is one of several viruses that cause viral hepatitis (inflammation of the liver).
- About 3.5 million people are estimated to be currently infected with hepatitis C in the U.S.
- Up to 85% of individuals who are initially (acutely) infected with hepatitis C will fail to eliminate the virus and will become chronically infected.
- Hepatitis C is spread through exposure to infected blood. Intravenous drug abuse with the use of contaminated, shared needles is the most common mode of transmission.
- The risk of acquiring hepatitis C through sexual contact or breastfeeding is very low.
- Generally, people with chronic infection with hepatitis C have no symptoms until they have extensive scarring of the liver (cirrhosis). Some individuals, however, may have fatigue and other non-specific symptoms before this occurs.
- In the U.S., infection with hepatitis C is the most common cause of chronic hepatitis and the most common reason for liver transplantation.
- Much progress has been made in the treatment of hepatitis C. The rate of cure has increased (above 90%-95%) with the development of direct-acting, all-oral antiviral medications.
- Treatment results in reduced inflammation and scarring of the liver in most patients who are cured of hepatitis C and also occasionally (but to a much lesser extent) in those who relapse or are not cured.
What is hepatitis C infection? How many people are infected?
Hepatitis C virus infection is an infection of the liver caused by the hepatitis C virus (also referred to as HCV). It is difficult for the human immune system to eliminate hepatitis C from the body, and infection with hepatitis C usually becomes chronic. Over decades, chronic infection with hepatitis C damages the liver and can cause liver failure. In the U.S., the CDC has estimated that approximately 29,718 new cases occurred in 2013. When the virus first enters the body there usually are no symptoms, so this number is an estimate. 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 U.S. related to hepatitis C infection. HCV infection is the leading cause of liver transplantation in the U.S. and is a risk factor for liver cancer.
What is the hepatitis C virus?
Hepatitis means inflammation of the liver. Hepatitis C is one of several viruses that can cause viral 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 fever.
There are at least six different genotypes (strains) of the virus which have different genetic profiles (genotypes 1 to 6). In the U. S., genotype 1 is the most common strain of hepatitis C. Even within a single genotype there may be some variations (genotype 1a and 1b, for example). Genotyping is used to guide treatment because some viral genotypes respond better to some therapies than to others.
Like human immunodeficiency virus (HIV), hepatitis C multiplies very fast and attains very high levels in the body. The genes that make the surface proteins of the virus also mutate (change) quickly, and thousands of genetic variations of the virus ("quasi-species") are produced daily. It is impossible for the body to keep up with making anti-HCV antibodies against all of the quasi-species circulating at one time. It has not been possible yet to develop an effective vaccine because the vaccine must protect against all genotypes.
Hepatitis C infection in the liver triggers the immune system, which leads to inflammation. Very few people experience typical hepatitis symptoms such as dark urine or clay colored stools in acute or early infection. Chronic hepatitis C usually causes no symptoms until very late in the disease, and hepatitis C has been referred to by sufferers as the "sleeping dragon." Over several years or decades, chronic inflammation may cause death of liver cells and scarring ("fibrosis"). Extensive scarring in the liver is called cirrhosis. This progressively impairs vital functions of the liver. Cirrhotic livers are more prone to liver cancer (hepatoma). Drinking alcohol speeds up liver damage with hepatitis C. Concurrent HIV infection also accelerates progression to cirrhosis.