Hepatitis D infection, which is caused by the hepatitis D virus (HDV), is a disease that infects the liver. It's similar to the other hepatotropic viruses (A, B, C and E) because it causes liver inflammation and produces similar symptoms, but HDV is unusual. It can only infect someone who has hepatitis B. HDV is unable to replicate itself, so to get around this problem, HDV depends on the hepatitis B virus (HBV) for replication (the process of making copies of itself).

What is Hepatitis D Infection Like?
Hepatitis D causes two kinds of infection: coinfection or superinfection. Coinfection is when someone is infected with HBV and HDV at the same time. Superinfection is when someone already has hepatitis B and then is infected with HDV. 

Coinfection is usually acute, and will resolve by itself. Superinfection has the possibility of being more serious. With superinfections, mild cirrhosis from hepatitis B can become severe and progressive cirrhosis (scarring of the liver). Some cases will lead to fulminant hepatitis.