Sound the alarm! The United States is suffering a silent epidemic of viral hepatitis. That message was recently delivered to a legislative committee by Howard Koh, MD, MPH, the assistant secretary for health in the Department of Health and Human Services. Several months later, Senator John Kerry (D–Mass.) introduced the Viral Hepatitis and Liver Cancer Control and Prevention Act of 2010. The bill calls for a national strategy to prevent and control hepatitis B and C and is endorsed by more than 100 national, hepatitis-focused organizations.

But what is hepatitis, and why are so many people concerned about it?

Hepatitis is liver inflammation caused by a group of viruses. There are five major types: hepatitis A, B, C, D and E. Of the quintet, A is not a chronic (long-lasting) infection, B and C are chronic conditions, and D and E are uncommon in the United States. In addition, vaccines are available for hep A and B, but not for hep C, D and E. (But the hep B vaccination prevents the development of hep D.)

In many cases, hepatitis may not pose a severe health threat. But when it’s chronic, the virus may damage the liver with an increasing amount of scar tissue, resulting in fatigue, mental confusion and even fatal liver disease and liver cancer.

How Hepatitis Is Most Often Spread

 Type Method of Transmission
Hep A Ingesting fecal matter from person-to-person contact or via contaminated food or drinks (that’s why it’s important to wash your hands after using the bathroom!)
Hep B Exchanging bodily fluids during sexual activity, sharing contaminated needles for drug injection, using contaminated medical or dental equipment, and passing the virus from an infected mother to newborn
Hep C Introducing infected blood into the bloodstream (for example through needle-sharing or using contaminated personal items such as razors)
Hep D This viral infection is spread like hep B, but hep D is rare in the United States
Hep E Ingesting fecal matter (usually from contaminated water in countries with poor sanitation; this type is uncommon in the United States)