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Microbiology · RNA hepatitis viruses

Hepatitis D virus !

  • Virus
  • Enveloped
  • Exam priority: medium

An incomplete virus that only infects people who have hepatitis B. It causes the most severe form of chronic viral hepatitis.

Updated 2026-11-01

Also called: HDV, delta virus, delta agent

At a glance

Shape
Spherical
Genome
Circular, single-stranded, negative-sense RNA
Envelope
Enveloped
Family
Kolmioviridae, genus Deltavirus
Size
About 36 nm

Morphology

  • The smallest RNA genome among animal viruses, viroid-like
  • Encodes only the delta antigen; its envelope is hepatitis B surface antigen (HBsAg)

Transmission

  • Blood and body fluids: shared needles, transfusions, sexual contact
  • Household spread in hyperendemic areas
  • Always needs simultaneous or prior hepatitis B infection

Reservoir: Humans infected with hepatitis B

Isolation precautions

What the care team adds to standard precautions.

  • Standard

Virulence factors

  • Relies on HBsAg to assemble particles and infect new hepatocytes
  • Superinfection of a chronic B carrier speeds fibrosis and cirrhosis
  • Classified as a human carcinogen

Diseases it causes

  • Hepatitis D by coinfection (together with hepatitis B) or superinfection (in a chronic hepatitis B carrier) Viral hepatitis →

Clinical picture

  • Coinfection: acute hepatitis that usually resolves; under 5% become chronic
  • Superinfection: severe, sometimes fulminant hepatitis with a high rate of chronicity
  • Faster progression to cirrhosis, decompensation and hepatocellular carcinoma than hepatitis B alone

Diagnosis

  • Test for anti-HDV antibodies in everyone who is HBsAg-positive
  • HDV RNA confirms active infection
  • Positive anti-HBc IgM suggests coinfection; negative with chronic HBsAg suggests superinfection

Treatment

Options are limited: pegylated interferon alfa, which works in a minority, and bulevirtide, an entry inhibitor approved in some countries. Nucleoside analogues against hepatitis B do not act on hepatitis D.

Drug class only; doses and regimens are set by the clinician from the current guideline.

Prevention

  • Hepatitis B vaccine prevents coinfection
  • Blood safety and safe injections
  • Harm reduction for people who inject drugs

Vaccine: No vaccine of its own; the hepatitis B vaccine in the PAI protects indirectly.

Test yourself

Think of the answer, then tap the question to see it.

Which hepatitis B protein does hepatitis D virus need?

Hepatitis B surface antigen (HBsAg), which forms its envelope.

How do coinfection and superinfection with HDV differ in outcome?

Coinfection usually resolves; superinfection of a chronic B carrier tends to chronicity and faster cirrhosis.

How is hepatitis D prevented at population level?

With the hepatitis B vaccine, because without hepatitis B there is no hepatitis D infection.

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Educational content on microorganisms; not a treatment guide and no substitute for a health professional's advice. No doses are given.

Sources: Hepatitis D (World Health Organization (WHO), 2025); Appendix A: Type and Duration of Precautions Recommended for Selected Infections and Conditions (CDC, 2024).

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Representative model, for educational purposes only.