Photo of liver tissue specimen extracted from a viral hepatitis patient.

Liver tissue specimen extracted from a viral hepatitis patient

Credit: CDC

Hepatitis is an inflammation of the liver. Viruses are the most common cause of hepatitis, but the condition can also be caused by other infections, heavy alcohol use, toxins, certain medications, and autoimmune disease. There are five main virus types that cause hepatitis---type A, B, C, D and E. Hepatitis A and E are typically caused by ingesting contaminated food or water. Type B commonly occurs through contact with infected blood, semen or other bodily fluid through sex, sharing needles or other drug-injection equipment or from mother to baby at birth. Hepatitis type C is a blood-borne virus that is largely spread by sharing needles or other drug injection equipment. Hepatitis D, which is transmitted through contact with infectious blood, occurs only among people with hepatitis B infection.

Why Is the Study of Hepatitis a Priority for NIAID?

Hepatitis B, C, and D afflict more than half a billion people worldwide and are responsible for more than a million deaths a year. Chronic infection with these viruses can lead to cirrhosis of the liver, end-stage liver disease, and liver cancer.

How Is NIAID Addressing This Critical Topic?

The NIAID Hepatitis Research Program supports research on all hepatitis viruses. However, commensurate with the magnitude of the medical burdens imposed by these viruses, the greatest emphasis is placed on the study of hepatitis C and hepatitis B viruses, which focuses on the understanding the pathogenesis and immunology of hepatitis viruses and developing novel therapeutics and vaccines against diseases caused by hepatitis viruses.

To learn about risk factors for hepatitis and current prevention and treatment strategies visit the MedlinePlus hepatitis site.

Disease-Specific Research

NIAID supports and conducts research on each of the five known hepatitis viruses—A, B, C, D and E. During the past 60 years, NIAID-supported investigators have been involved in many important breakthroughs in hepatitis research, including the discovery of the hepatitis A and E viruses, the development of one of the first diagnostic tests for hepatitis A, and studies that led to the creation of the hepatitis A vaccine and laid the foundation for advanced development of a hepatitis E vaccine. In addition to basic research to understand the molecular processes of hepatitis infection, our research involves significant focus on the development of new treatments and vaccines to prevent acute and chronic hepatitis infection.

Content last reviewed on July 16, 2015