Hepatitis C affects some 130–170 million people worldwide, including 3.2 million Americans, with 20 percent of the affected individuals developing cirrhosis of the liver and liver cancer. Worldwide, hepatitis C infections cause at least 250,000 deaths annually. Approved in 2011, experts view Merck’s Victrelis (boceprevir) and Vertex’s Incivek (telaprevir) to be the most dramatic advances in the treatment of hepatitis C in decades. These orally administered drugs double previous cure rates to 80 percent and shorten the drug treatment period by one-half, to as few as twenty-four weeks.
Hepatitis is an inflammation of the liver, the body’s largest gland. The liver performs a number of complex functions involving digestion, nutrient and vitamin metabolism, synthesis of proteins required for blood clotting, removal of bacteria from the blood, and the metabolism and inactivation of foreign substances, such as drugs. Hepatitis has a number of causes, including infections by several types of virus, the most common of which are designated A, B, and C. They differ in their severity, mode of transmission, prevention, and treatment.
Hepatitis A is often mild and primarily spread by ingestion of fecal-contaminated food or water. Available vaccines are 95–100 percent effective in preventing this condition. Hepatitis B is more severe and is most commonly transmitted by sexual contact with an infected individual, by sharing contaminated needles, and during childbirth, when an infected pregnant woman transmits the virus to her baby. The hepatitis B vaccine—among the safest of vaccines—provides protection to more than 85 percent of individuals after the second dose.
Before the testing of blood supplies in 1992, millions of Americans became infected with hepatitis C after blood transfusions. Now, most individuals become newly infected after sharing contaminated needles, and they are unaware of their infection until years later, when symptoms of liver damage become evident. Earlier hepatitis C treatments with interferon and ribavirin acted by boosting the immune system. By contrast, Victrelis and Incivek block protease, an enzyme the hepatitis C virus requires in order to reproduce itself. Other protease inhibitors are integral components of drug cocktails (HAART) used to treat HIV/AIDS infections.
SEE ALSO Acyclovir (1982), AZT/Retrovir (1987), HAART (1996).
The liver, the body’s largest internal organ, is highlighted in this illustration of the human abdominal cavity. The liver is a soft, pinkish-brown, triangular organ, normally weighing about 3.5 lbs. (1.6 kg).