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Delta agent (Hepatitis D)


Delta agent is a type of virus called hepatitis D. It causes symptoms only in people who also have hepatitis B infection.

Alternative Names

Hepatitis D virus


Hepatitis D virus (HDV) is found only in people who carry the hepatitis B virus. 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:

  • Abusing intravenous (IV) or injection drugs
  • Being infected while pregnant (the mother can pass the virus to the baby)
  • Carrying the hepatitis B virus
  • Men having sexual intercourse with other men
  • Receiving many blood transfusions


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

Exams and Tests

You may need the following tests:

  • Anti-delta agent antibody
  • Liver biopsy
  • Liver enzymes (blood test)


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

You may receive a medicine called 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.

Outlook (Prognosis)

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).

Possible Complications

Complications may include:

  • Chronic active hepatitis
  • Fulminant hepatitis

When to Contact a Medical Professional

Call your health care provider if you have symptoms of hepatitis B.


Steps to prevent the condition include:

  • Detect and treat hepatitis B infection as soon as possible to help prevent hepatitis D.
  • Avoid intravenous drug (IV) abuse. If you use IV 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.



Perrillo R. Hepatitis B and D. In: Feldman M, Friedman LS, Brandt LJ, eds. Sleisenger and Fordtran's Gastrointestinal and Liver Disease. 9th ed. Philadelphia, PA: Elsevier Saunders; 2010:chap 78.

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