Hepatitis is the medical term for inflammation of the liver. Hepatitis may be acute (lasting only for the short term, after which a person recovers) or chronic (lasting for the long term, usually more than 6 months).
There are many causes of hepatitis, including viruses, alcoholism, and medications. Viral hepatitis is now a major cause of chronic hepatitis in North America. There are five hepatitis viruses: A, B, C, D, and E. There are also other viruses that can cause liver inflammation, like Epstein-Barr virus and cytomegalovirus, but these viruses are not called hepatitis viruses.
Hepatitis A and B (HAV and HBV) are common causes of liver inflammation in North America. Statistical data from 1999 and 2006 showed that around 600 to 900 new cases per year of HAV and HBV were being diagnosed in Canada. Since many infected people have no symptoms; however, we can assume the true rate of infection is higher than this. Many experts believe that up to one-third of the population has been infected with HAV at some point.
Among people born in North America, hepatitis A is most common in children and young adults, while hepatitis B is most common in adults between the ages of 20 and 40 years.