Viral hepatitis is a significant global health concern. Scientists have identified several different viruses—hepatitis A, B, C, D, and E—which, collectively, account for the majority of viral hepatitis infections in humans. Of these, hepatitis A and E viruses are transmitted through the fecal-oral route and cause only acute infections that are generally resolved without complications and confer long-term immunity. Hepatitis B, C, and D, on the other hand, are transmitted through infected blood, frequently causing chronic infection, and are exceedingly dangerous pathogens. These three viruses afflict more than half a billion people worldwide and are responsible for over a million deaths a year. Chronic infection with these viruses can lead to cirrhosis of the liver, end-stage liver disease, and liver cancer.
Effective vaccines are now available against hepatitis A and B viruses, and a vaccine for the hepatitis E virus is in advanced clinical trials. The vaccine against hepatitis B also protects against hepatitis D because replication of the latter is dependent on hepatitis B virus; hepatitis D can therefore only exist as a co-infection with hepatitis B. There currently is no vaccine against the hepatitis C virus. There are moderately successful treatment options for hepatitis B and C chronic infections.
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 following:
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Last Updated November 02, 2009