According to the World Health Organization (WHO) and U.S. Centers for Disease Control and Prevention (CDC), about 4.1 million Americans (1.6 % of the U.S. population), of whom 3.2 million are chronically infected, and 170 million people worldwide (3% of the world's population) are infected with HCV. Of the people infected with HCV today, less than 2 percent are receiving adequate therapy for their disease.
Transmission
Transmission of the virus occurs when blood or body fluids from an infected person enters the body of a person who is not infected. Hepatitis C can be spread through sharing needles when "shooting" drugs, through sexual contact, through certain occupational exposure, or perinatal infection from an infected mother to her baby during birth. The most common route of transmission in the U.S. of hepatitis C is intravenous drug use. Transfusion-related acute hepatitis C is now very rare.
Natural History
The acute stage, which occurs 2 weeks to 6 months after infection, usually is so mild that most people don't know they are sick;
- 80% of persons have no signs or symptoms
- When symptoms are present, the most common are fatigue (~70 percent), abdominal pain/discomfort (~20 percent), anorexia (~15 percent) and weight loss (~5 percent). The majority of chronic HCV carriers have hepatomegaly (70 percent), while some have an enlarged, palpable spleen (20 percent);
- Up to 85 percent of newly infected patients progress to develop chronic infection;
- 70 percent of those chronically infected persons will develop chronic liver disease;
- Liver damage (cirrhosis) develops in about 10 percent to 20 percent of persons with chronic infection;
- Liver cancer is a risk to patients with chronic infection over a period of 20 to 30 years;
- One to 5 percent of persons infected may die as a result of chronic liver disease
- Liver damage caused by HCV infection is the leading indication for liver transplantation in the United States.
There are currently no vaccines available to prevent hepatitis C, but there are medications that can be used to fight chronic infection. However, this treatment is not an option for everyone, and only about 50% of those who receive the treatment are cured of the infection. In addition, there are substantial limitations to the use of current regimens, including reduced response to treatment in subjects with HCV genotype 1 (the most prevalent type of infection in the U.S. and Europe) infection and considerable side effects that cause approximately 20 percent of subjects to discontinue therapy.
This makes Hepatitis C is one of today’s greatest unmet medical needs. ViroPharma and Wyeth are on the cutting edge of identifying and developing potent antivirals targeting the hepatitis C virus; the hope is to one day improve the cure rate with better tolerated drugs, and to increase the number of patients who seek therapy thanks to these improvements.