Hepatitis D testing: who should be tested

Hepatitis D, also called hepatitis delta, is an infection that can occur only in someone who has hepatitis B. It can cause more aggressive disease and speed the development of fibrosis, cirrhosis and liver cancer.

Because many people have no symptoms, testing is the way to find it. Current recommendations favor testing every HBsAg-positive person at least once, with repeat testing after a new exposure or when the course of liver disease cannot be explained by hepatitis B alone.

Who should be tested?

Testing is appropriate for people with positive HBsAg, especially those with:

• Birth or residence in a region where hepatitis D is more common.
• Current or previous injection drug use.
• HIV or hepatitis C.
• A sexual partner or household contact with hepatitis D.
• Multiple sexual partners or male-to-male sexual contact.
• Elevated liver enzymes despite a low or controlled hepatitis B viral load.
• Cirrhosis or liver disease progressing faster than expected.

The absence of these factors does not rule out infection. Several guidelines therefore recommend universal testing among people living with hepatitis B when the test is available.

Which test comes first?

The first test is the anti-HDV antibody. A positive result shows previous exposure but does not prove that infection is still active.

The next step is a molecular test for HDV RNA. Detectable RNA confirms active infection and the need for specialist assessment. Assays can vary among laboratories, so testing at a center with appropriate experience is useful.

Coinfection and superinfection

Hepatitis D can be acquired in two ways:

• Coinfection: hepatitis B and D are acquired at the same time. This can cause severe acute hepatitis, but both viruses are often cleared.
• Superinfection: a person with chronic hepatitis B later acquires hepatitis D. This is more likely to become chronic and progress rapidly.

Clinicians interpret HBsAg, IgM anti-HBc, hepatitis B viral load, hepatitis D RNA and liver enzymes to distinguish these situations.

What happens after a positive result?

Active infection requires fibrosis assessment with elastography or other methods, evaluation for portal hypertension and surveillance for hepatocellular carcinoma when indicated. Alcohol, fatty liver and other sources of additional injury are reviewed as well.

Treatment is changing. Pegylated interferon can be used in selected patients, and bulevirtide is approved in Europe for compensated chronic hepatitis D. Availability differs among countries and should not be assumed in Chile. Other treatments are under investigation.

Can hepatitis D be prevented?

There is no specific hepatitis D vaccine, but the hepatitis B vaccine also prevents hepatitis D because the delta virus needs HBV to infect a person. Vaccination protects those who do not yet have hepatitis B. It cannot remove the risk in someone who is already HBsAg-positive, who should avoid blood exposure and use barrier protection during sex as appropriate.

Finding hepatitis D changes follow-up and may change treatment. It should not be left out of the assessment of chronic hepatitis B.

See also

• Hepatitis D
• Hepatitis B
• Hepatitis B blood tests
• Cirrhosis