Hepatitis D virus (HDV) is found only in people who carry the hepatitis B virus. It can occur with a new infection of hepatitis B (coinfection) or on top of a hepatitis B infection (superinfection). HDV may make liver disease worse in people who have either recent (acute) or long-term (chronic) hepatitis B. It can even cause symptoms in people who carry hepatitis B virus, but who never had symptoms.

Hepatitis D infects about 15 million people worldwide. It occurs in a small number of people who carry hepatitis B.

Risk factors include:

• Being infected while pregnant (the mother can pass the virus to the baby).
• Carrying the hepatitis B virus.
• Being in a high-risk group for getting hepatitis B or D. Examples include sharing body fluids such as through sexual contact, household blood or saliva contact, or sharing needles/drug equipment. 
• Receiving many blood transfusions. The US blood supply is screened for hepatitis virus, so this is uncommon.
• Using intravenous (IV) or injection drugs.
• Rarely, a baby can get hepatitis D from a mother with hepatitis D.

Hepatitis D may make the symptoms of hepatitis B worse.

Symptoms may include:

• Abdominal pain
• Dark-colored urine
• Fatigue
• Jaundice
• Joint pain
• Loss of appetite
• Nausea
• Vomiting

You may need the following tests:

• Anti-hepatitis D antibody. Blood tests for hepatitis B will also be done. 
• Liver biopsy is occasionally done.
• Liver enzymes (blood test) and other bloodwork to check for other liver diseases and see how damaged the liver is.
• Imaging tests such as an abdominal ultrasound or a special ultrasound called elastography, to look at the liver and see how damaged it is.
• Evaluation for liver cancer.

Many of the medicines used to treat hepatitis B are not helpful for treating hepatitis D.

You may receive a once weekly injectable medicine called pegylated alpha interferon for up to 12 months if you have a long-term HDV infection. A liver transplant for end-stage chronic hepatitis B may be effective.

People with an acute HDV infection most often get better over 2 to 3 weeks. Liver enzyme levels return to normal within 16 weeks.

About 1 in 10 of those who are infected may develop long-term (chronic) liver inflammation (hepatitis).

Complications may include:

• Chronic active hepatitis
• Acute liver failure

Contact your health care provider if you have symptoms of hepatitis D.

Steps to prevent the condition include:

• Detect and treat hepatitis B infection as soon as possible to help prevent hepatitis D.
• Avoid intravenous (IV) or injection drug use. If you inject drugs, avoid sharing needles.
• Get vaccinated against hepatitis B.

Adults who are at high risk for hepatitis B infection and all children should get this vaccine. If you do not get Hepatitis B, you cannot get Hepatitis D.