Condition Basics

What is viral hepatitis?

Viral hepatitis is an inflammation of the liver caused by an infection with a virus.

What causes it?

Most cases of viral hepatitis are caused by hepatitis A, B, C, D, and E viruses. Less common causes of hepatitis are cytomegalovirus (CMV) and the Epstein-Barr virus. (This is a virus that causes infectious mononucleosis.)

How does it spread?

A virus that causes hepatitis can be spread from one person to another.

Hepatitis B, C, and D viruses are spread when an uninfected person comes in contact with blood, semen, or vaginal fluid (such as menstrual blood) that's infected with one of these viruses.

Hepatitis A and E viruses are spread by contaminated food and water. They're also spread through direct contact with contaminated stool (feces). Hepatitis E also might be spread by contact with an infected pig. Hepatitis E is very rare in developed countries. Hepatitis D only occurs along with hepatitis B.

How is it diagnosed?

Blood tests are used to diagnose viral hepatitis. In their early stages, viruses that cause hepatitis are hard to tell apart. But within weeks after infection, blood tests can show which virus is the cause of hepatitis. (An exception is hepatitis E, for which a blood test is not widely available.)