Hepatitis D is caused by a defective RNA virus (delta agent) that can replicate only in the presence of hepatitis B virus. It occurs uncommonly as a coinfection with acute hepatitis B or as a superinfection in chronic hepatitis B.
Hepatitis D is usually transmitted by parenteral or mucosal contact with infected blood or body fluids. Infected hepatocytes contain delta particles coated with hepatitis B surface antigen (HBsAg).
Prevalence of hepatitis D virus (HDV) varies widely geographically, with endemic pockets in several countries. Parenteral drug users are at relatively high risk, but HDV, unlike hepatitis B virus (HBV), has not widely permeated the homosexual community.
Symptoms and Signs of Hepatitis D
Acute hepatitis D infection typically manifests as
Diagnosis of Hepatitis D
- Serologic testing
In the initial diagnosis of acute hepatitis, viral hepatitis should be differentiated from other disorders causing jaundice (see figure Simplified approach to possible acute viral hepatitis ). If acute viral hepatitis is suspected, the following tests are done to screen for hepatitis viruses A, B, and C:
- IgM antibody to hepatitis A virus (IgM anti-HAV)
- Hepatitis B surface antigen (HBsAg)
- IgM antibody to hepatitis B core (IgM anti-HBc)
- Antibody to hepatitis C virus (anti-HCV) and hepatitis C RNA (HCV RNA) PCR
If serologic tests for hepatitis B confirm infection and clinical manifestations are severe, antibody to HDV (anti-HDV) levels should be measured. Anti-HDV implies active infection. It may not be detectable until weeks after the acute illness.
Treatment of Hepatitis D
- Supportive care
No treatments attenuate acute viral hepatitis, including hepatitis D. Alcohol should be avoided because it can increase liver damage. Restrictions on diet or activity, including commonly prescribed bed rest, have no scientific basis.
The only drug approved for treatment of chronic hepatitis D is interferon-alfa, although pegylated interferon-alpha is likely equally effective. Treatment for 1 year is recommended, although whether longer treatment courses are more effective has not been established. Hepatitis D is also treated in the context of clinical trials.
Prevention of Hepatitis D
No product exists for immunoprophylaxis of hepatitis D. However, prevention of HBV infection prevents HDV infection.
- Hepatitis D occurs only with hepatitis B.
- Suspect hepatitis D particularly when cases of hepatitis B are severe or when symptoms of chronic hepatitis B are worsening.
- Treat and prevent infection as for hepatitis B.