What is Hepatitis D? 

Hepatitis D, also known as “delta hepatitis,” is a liver infection caused by the hepatitis D virus (HDV). Hepatitis D is uncommon in the United States. Hepatitis D only occurs in people who are infected with the hepatitis B virus because HDV is an incomplete virus that requires the helper function of HBV to replicate. HDV can be an acute, short-term, infection or a long-term, chronic infection. Hepatitis D is transmitted through percutaneous or mucosal contact with infectious blood and can be acquired either as a coinfection with HBV or as a superinfection in people with HBV infection. There is no vaccine for hepatitis D, but it can be prevented in people who are not already HBV-infected by hepatitis B vaccination.