The word hepatitis refers to an inflammation (-itis) of the liver (hepa-). (See What is the liver?) Hepatitis C (Hep C) is a specific liver disease caused by the hepatitis C virus (HCV). The virus is an RNA virus and uses liver cells to create copies of itself, killing those cells in the process. The infection was first labeled “non-A, non-B” hepatitis prior to being identified as the hepatitis C virus in 1989.
Worldwide, about 170 million people are infected with HCV. In Canada, it is estimated that 250,000 people are infected, and 110,000 of them live in Ontario. Roughly, 35% of people with the virus do not know that they are infected.
Acute Infection
Acute hepatitis C refers to the first phase of the disease, when a person is newly infected. At this stage, about 20% of people infected with HCV appear to clear the virus from their body on their own within a few months. These people still test positive for HCV antibodies but do not have active virus in their bodies. (For more information, see Types of tests.) There is no vaccine for or immunity to HCV, so people can be re-infected.
Chronic Infection
Around 80% of people with acute infection do not clear the virus and the disease progresses to chronic infection.
Inflammation and Fibrosis
Over time, the virus destroys liver cells and leads to inflammation in the liver. This damage results in the formation of scar tissue called fibrosis. Progression of the disease is slow, often over the course of 20–30 years, during which time a person may not show any symptoms.
During the decades of chronic infection, one out of five people can develop heavier scarring on the liver, called cirrhosis. There are two kinds of cirrhosis. In compensated cirrhosis, the liver is still partially functioning. In decompensated cirrhosis, the damage becomes so severe that the liver stops working and a transplant is required. Five to 10% of people with cirrhosis can also develop a form of liver cancer called hepatocellular carcinoma (HCC).
Genotypes
There are six major genotypes of HCV. A genotype is a genetic variation of the hepatitis C virus and different genotypes are prevalent in different parts of the world. In North America, HCV infections usually involve genotype 1 virus, with genotypes 2 and 3 responsible for a smaller percentage of cases. Knowing the genotype is important when making decisions about treatment.
Transmission
Transmission of HCV is through exposure to blood of an HCV-infected person.
The impact and social costs of this disease are expected to escalate in coming years. Because as many as one-third of people infected with HCV do not know they have the infection, the focus of public health in Canada today is to prevent new HCV infections by:
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