Hepatitis Viruses: The major cause for hepatitis and liver cancer.


Hepatitis is an inflammation of the liver, a largest organ that performs essential functions for life. The major cause for hepatitis is infection by hepatitis virus, namely hapatitis C virus (HCV), hepatitis B virus (HBV), and other types such as A, D, E, and G. Drugs and medication are minor contributing factors.

The most common types of hepatitis viruses are C, B, and A, of which hepatitis A virus is the least serious type. Hepatitis B, C, and D are transmitted via human contact involving human blood, and especially for HBV, via sexual activity. Hepatitis A and E are transmitted through food and water contaminated with these virueses. Hepatitis B and C viruses occasionally cause chronic hepatitis, and pose greatest potential damages to the liver on the long term basis. The popularity of HBV is decreasing due to the availability of effective vaccine. No vaccine is yet available for hepatitis C virus prevention.

Majority of hepatitis B and C transmissions have occurred through blood transfusion, especially before 1975 (for HBV) or 1992 (for HCV), exposure to someone else's blood (for hospital workers), hemodialysis, sharing needles for drug injection, sexual contacts with HBV (and also HCV) carriers, and tattooing or body piercing.

Hepatitis B and C are very common. In the US, there are more than a million people with HBV, and 4 million people with HCV. Over 80% of HCV infection will develop to chronic hepatitis C. The mority of people in developing world including China, and other Asian countries, Pacific islands, and sub-Saharan Africa become infected with hepatitis B during their childhood. High rate of chronic HBV infections (5% of population) are also found in India, Middle East, central and eastern Europe, and Amazon. About 25% of the people who are chronically infected eventually die of liver cancer or cirrhosis. Each year, quarter a million people die of liver failure in China alone. Worldwide, an estimated 170 million people are chronically infected with HCV and 3-4 million new infections occur each year.