Hepatitis D is caused the by HDV virus which leads to liver inflammation. Hepatitis D infection is seen mainly in Central Africa, the Middle East, and central South America. Low rates of infection are present in most of Europe, the United States, and Australia. In the United States, HDV is confined to people such as medical personnel, drug addicts, and hemophiliacs who are exposed to blood or blood products. The virus is a "defective" RNA virus that requires the presence of the HBV virus to reproduce. It cannot infect a person who is not already infected with HBV, though it may be acquired either at the same time as an HBV infection, or later, as a superinfection in someone who already has HBV.

People with simultaneous, or co-infection, of HBV and HDV have a much higher risk of fulminant hepatitis (2% to 20%) than do people with HBV alone. While the likelihood of developing chronic HBV infection usually decreases in the presence of HDV superinfections, most patients will develop chronic HDV infections which produce more frequent and more severe liver disease and cirrhosis than does chronic HBV infection alone.

How is HDV spread?

It is spread through anyone coming into contact with infected blood, contaminated needles, or having sexual contact with an HDV-infected person.

Symptoms of HDV hepatitis

They are similar to those for HBV hepatitis. Many who are infected have no symptoms or have jaundice and flu-like symptoms similar to hepatitis B. After being infected with the HDV virus, it takes about 2 to 8 weeks to develop HDV hepatitis.

How is HDV diagnosed?

The Hepatitis D virus is diagnosed by a blood test that indicates anti-HDV. Many who are infected with HBV hepatitis also show a co-infection with HDV. Being infected with both HDV and HBV seems to make the acute hepatitis more severe and cause a higher-than-normal rate of chronic hepatitis.

Is there a vaccination for HDV?

Infection with hepatitis D can be prevented by vaccinating those at risk with hepatitis B vaccine. However, those who already have hepatitis B cannot prevent infection with HDV because there is no HDV vaccine.

How is HDV treated?

The treatment for HDV chronic hepatitis is the same as for HBV; the use of interferon can be a successful treatment for some. The prognosis for those with chronic HDV infection is often poor.