Hepatitis literally means "swollen liver." Hepatitis C (HCV) is one of five (A, B, C, D, and E) viruses that cause the condition, which can also result from non-viral causes such as alcoholism. HCV attacks the liver, the organ that detoxifies drugs, alcohol, and environmental poisons, disposes of worn-out blood cells, and aids in digestion.
HCV was first recognized as a distinct form of hepatitis in the late 1960s. At that time, scientists lacked a sophisticated method to identify the causative agent and referred to the disease as "non-A, non-B" hepatitis. It was identified in 1989 using techniques developed in HIV research to clone portions of the virus's RNA. The virus itself has still never been seen.
More than 4 times as many people are infected with HCV than HIV-there are an estimated 170 million HCV sufferers worldwide.
HCV infection is the leading reason for liver transplants. As many as 70 percent of victims develop chronic liver disease.
Symptoms can take 10 years to appear, and include fatigue, jaundice, dark urine, abdominal pain, loss of appetite, and nausea-but most infected people exhibit no symptoms. Transmission is through blood and blood products. Intravenous drug use causes 60 percent of all new cases.
Despite increases in the number of people being diagnosed with HCV, new infections have actually decreased by more than 80 percent since the virus was identified. Blood screening tests and procedures used to kill the virus have helped to
reduce new infections.
The virus mutates. By varying its structure, it has evolved into six known genotypes and more than 50 subtypes.
Although there is no vaccine for HCV, a combination of the drugs interferon and ribavirin administered for 6 months to a year is the treatment of choice. Interferon enhances the immune system and ribavirin stops HCV's replication.
With treatment, the virus can be eradicated from the body-but treatment is effective in just 30 to 50 percent of patients. The side effects-fatigue, flu-like symptoms, and depression-can be so severe many patients cease treatment.
By attaching a substance known as polyethylene glycol (PEG) to the interferon molecule, researchers have modified and improved interferon. The new version, called pegylated interferon, is better at fighting the virus because it stays in the body longer than standard interferon.
Researchers are developing new treatments for HCV-protease, helicase, and polymerase inhibitors. Similar to HIV antiviral agents, they will work to block enzymes involved in HCV replication.
-Compiled by Emily Bergeron