Should people who are HBsAg positive be tested for hepatitis D (HDV)?

First understand that HDV depends on HBV

Hepatitis D virus needs hepatitis B surface antigen to spread and cause infection, so it occurs only in people who currently have HBV infection. That is why an HBsAg-positive result is the practical trigger to ask whether HDV testing is needed.

HDV can make liver disease progress faster in some people. A person may not feel different, so the decision to test should not depend only on symptoms.

Who should ask about HDV testing

If you are HBsAg positive, ask your clinician whether HDV antibody testing and, if positive, HDV RNA testing are appropriate. This is especially important if you have unexplained ALT/AST elevation, advanced fibrosis or cirrhosis, injection drug exposure, HIV or HCV coinfection, sexual or household exposure risk in areas where HDV is more common, or birth or long-term residence in a higher-prevalence region.

Guidelines and public health resources differ in how broadly they recommend testing, but the practical message is simple: HBsAg-positive people should not assume HDV has been considered unless it is written in the plan.

Transmission and everyday life

HDV spreads through blood and sexual exposure routes similar to HBV. It does not require isolation from ordinary daily contact. Family members and partners should focus on hepatitis B screening, vaccination if susceptible, safer sex when needed, and avoiding shared razors, toothbrushes, needles, or equipment that may have blood.

If HDV testing is positive

Do not try to find medicine on your own. Ask for referral to a liver or infectious disease clinician familiar with hepatitis D. The next plan may include HDV RNA, HBV DNA, ALT/AST, bilirubin, INR, platelets, fibrosis assessment, ultrasound, liver cancer surveillance when indicated, and discussion of treatment options or clinical trials.

Action checklist

If you are HBsAg positive, ask whether HDV antibody testing is needed. If antibody is positive, ask whether HDV RNA confirms active infection. Bring HBV DNA, ALT/AST, fibrosis or cirrhosis reports, HIV/HCV results, and exposure history. Make sure family and partners know their hepatitis B screening and vaccine status. Seek care promptly for jaundice, abdominal swelling, vomiting blood, black stools, confusion, or rapidly worsening fatigue.