Hepatitis C infects an estimated 170 million persons worldwide and 4 million persons in the United States. Co-infection with HIV is common and rates among HIV positive populations are higher.
The infection is spread by blood exchange and, less commonly, sexual contact. Before serological tests became available, it was often caused by the use of medical products derived from blood and by blood transfusion.
Although it can be spread sexually, and vertically (from mother to child), transmission by these routes is not as likely as with hepatitis B. hepatitis C is not considered an Sexually Transmitted Disease (STD). The CDC reports that only 1.5% of partners of hepatitis C carriers test positive for the disease. In most developed countries, it is usually seen primarily in intravenous drug users.
In most cases, acute hepatitis C infection has no symptoms and becomes chronic, and can cause long term damage to the liver, including cirrhosis and hepatocellular carcinoma. Severe liver damage may not develop for 10-40 years after infection.
Currently, serological tests are available to check for infection. In addition, PCR can be used for more sensitivity and to elucidate a genotype for the infection. There are 6 major known genotypes.
Treatment is mainly based on interferon, combined with other drugs; though this action does not guarantee results. Currently, the preferred treatment is pegylated interferon together with ribavirin. Studies have shown sustained cure rates of 75% or better in people with genotypes 2 or 3 HCV (which is easier to treat) and about 50% in those with genotype 1. It is well known that alcohol makes HCV virus proliferate faster, and makes interferon treatment less effective.
Unlike hepatitis A and B, there is no vaccine for hepatitis C.