Viral hepatitis is an infection that inflames the liver. Although there are five types of viral hepatitis, each caused by a different virus, the most common types in the United States are hepatitis A, B and C. Millions live with chronic viral hepatitis, and some do so unknowingly because they do not always experience frequent symptoms.

Here is everything you need to know about hepatitis, including symptoms and treatment options, courtesy of Northwestern Medicine Hepatologist Laura M. Kulik, MD.

Hepatitis A

Hepatitis A is transmitted through ingestion of contaminated food or water, or through contact with an infectious person. Those who travel internationally in developing countries should be vaccinated against this virus and should be particularly careful with food or water in foreign countries. Symptoms can include but are not limited to:

• Dark urine
• Stools that are gray or lighter in color than usual
• Nausea and vomiting
• Itchy skin
• Jaundice (yellowish eyes and skin)

Generally, healthy people recover from hepatitis A without specific treatment after a few weeks.

Hepatitis B

More than 2 billion people around the world have been infected with hepatitis B. Unlike hepatitis A, hepatitis B can be a chronic infection in some. In those people, it can lead to cirrhosis and liver cancer. In the United States, most cases of hepatitis B originate with unprotected sex with someone who is infected.

Others who are at risk include people who:

• Work with human blood, body fluids or needles
• Had blood transfusions or organ transplants before the early 1990s
• Have HIV (human immunodeficiency virus) or hepatitis C infections
• Use IV (intravenous) drugs

Acute hepatitis B usually doesn't require treatment in people whose immune system can fight the infection. While there is no cure for chronic hepatitis B, oral or injected medications can slow the disease process or prevent further liver damage.

Hepatitis C

The most common form of viral hepatitis in the United States, hepatitis C virus, is spread by contact with an infected person's blood. Hepatitis C is frequently chronic and can lead to cirrhosis and liver cancer.

People who are at risk include those who:

• Use intravenous drugs
• Have a blood-clotting disorder and received clotting factors before 1987
• Have kidney failure and get dialysis treatment
• Had blood transfusions or organ transplants before the early 1990s
• Have tattoos or body piercings
• Have unprotected sex
• Have HIV

If hepatitis C has caused liver damage, treatments may include surgery, transplant and ongoing monitoring for liver cancer and other issues.