Tuesday, July 19, 2011

Hepatitis C phenotypes

Cancer caused by HCV

Hepatitis C virus (HCV) is the most common bloodborne infectious agent in the United States. It causes hepatitis - inflammation of the liver. Approximately three-quarters or more of infected individuals go on to develop chronic disease after infection (currently 3 million people), many of whom originally appeared asymptomatic, but some may experience other phenotypes with or without treatment, including spontaneous viral clearance and sustained virological response. HCV is most commonly spread through contaminated blood, including intravenous drug use. Sexual transmission is also possible.

Read more about the three phenotypes of HCV infection below the jump.


HCV infects the liver, causing inflammation known as hepatitis (i.e. viral hepatitis). HCV is most commonly spread through contaminated blood, including intravenous drug use. Sexual transmission is possible, but not efficient according to the CDC. Approximately three-quarters of infected individuals, many of whom originally appeared asymptomatic, go on to develop chronic disease after infection. More than 3 million people live with chronic disease due to infection, but this is only one of three phenotypes (or physical manifestations of the disease) seen in HCV patients. The other two potential phenotypes are spontaneous viral clearance and sustained virological response.

Spontaneous viral clearance

Research has shown that as many as 25 percent of adults infected with HCV clear the virus on their own. Spontaneous clearance tends to be higher in women and those who experience an acute hepatitis upon infection. The immune response upon exposure, as opposed to the delayed and initially asymptomatic response seen in the majority of people who are infected, indicates the body’s defenses are activated against the infection. Children, who tend to become infected by transfusion, appear to have similar spontaneous clearance rates, which is not true for other forms of viral hepatitis (e.g., HBV).

The symptoms of acute hepatitis C are like many other viral infections: fatigue, loss of appetite, muscle aches, and fever. Due to the involvement of the liver, jaundice (a yellowing of the whites of the eyes and skin) may occur, but it is rare with the initial infection. Spontaneous viral clearance is defined by the absence of HCV RNA in the blood in the absence of treatment after known infection.

Sustained virological response

Sustained virological response is considered the end point of treatment, meaning that it is the goal of treatment – to suppress the virus and prevent symptoms of chronic infection. A combination of drugs (such as pegylated interferon and ribavirin) is used to prevent virus replication and the common complications of cirrhosis and liver cancer. In the last decade, clinicians have attempted to find the most effective therapy to reach a sustained virological response in as many chronically infected patients as possible. Genetic testing may help achieve this goal.

Chronic hepatitis C

The majority of those infected with HCV will not spontaneously clear the virus. For those who are not successfully treated to reach a sustained virological response, chronic infection of the liver can lead to cirrhosis (scarring of the liver). Jaundice, rash, blood clotting problems, male breast development, and spider-like vessels on the skin may occur as cirrhosis occurs. Advanced cirrhosis is life-threatening due to the reduced function of the liver and liver failure, portal hypertension, ascites (fluid accumulation in the abdomen), anemia, thrombocytopenia, and esophageal varices. Joint pain, dark-colored urine, grey-colored stools, abdominal pain, and vomiting/nausea are also common symptoms of chronic HCV infection according to the CDC.

Hepatocellular carcinoma is the most common form of liver cancer. Anti-HCV drugs can be used to prevent tumor growth. Some research has indicated that metabolic syndrome combined with chronic hepatitis C increases the risk for cancer, whereas a sustained virological response may not avoid liver cancer development.


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