Hepatitis D, also known as delta hepatitis, is a liver infection caused by the hepatitis D virus (HDV). Hepatitis D only occurs in people who are infected with the hepatitis B virus since HDV requires the help of HBV to replicate. When HDV is acquired at the same time as HBV, this is called a coinfection. A superinfection results when a chronic HBV carrier acquires HDV.

Hepatitis D can be an acute infection or a chronic infection. Compared to infection with just hepatitis B, HDV coinfection and superinfection causes more severe complications, leading to increased risk for liver failure in acute infections. Roughly 60 to 70 percent of people with chronic hepatitis D develop cirrhosis, and progression occurs rapidly averaging 5 to 10 years. HDV may also progress to liver cancer. People with hepatitis D have the highest death rate of all the hepatitis infections, at 20 percent.

Hepatitis D is spread the same way that hepatitis B is transmitted. There is no vaccine for hepatitis D, but hepatitis B vaccination prevents HDV in people who are not already HBV-infected. There is no immunoglobulin available for exposure and no treatment for hepatitis D.

Hepatitis D is found worldwide, and is uncommon in the United States. The highest prevalence of HDV is in the Amazon Basin, the Mediterranean Basin and Central Africa.

Last Reviewed: March 4, 2019