Hepatitis D virus hepatitis

The delta agent is a small, RNA particle that is coated with HBsAg. It is a viroid which is incapable of replication without co-existent HBV infection. HDV suppresses the expression of HBV DNA and causes ongoing or progressive liver disease.

HDV is most common in Southern Europe, the Balkans, Middle East, South India and parts of Africa.

HDV is transmitted by blood. It can affect all of the risk groups for HBV. It is most strongly associated with IV drug abuse and is infrequent among homosexuals. Up to 10% of HBV carriers have anti-HDV antibodies. HDV infection can be reactivated by HIV infection.

Co-infection with HDV and HBV rarely leads to chronic disease but fulminant hepatitis is more likely than with HBV alone:

• chronic hepatitis D causes more rapidly progressive liver disease than HBV alone (1):
  • about 30% to 70% of patients with chronic hepatitis D have cirrhosis at diagnosis and more than 50% die of liver disease within 10 years of diagnosis

Superinfection of a chronic carrier of HBV with HDV worsens the prognosis:

• acute hepatitis is likely in a previously healthy carrier
• mild hepatitis may become fulminant
• there is an increased risk of chronic progressive disease, often terminating in cirrhosis

HBsAg carriers with delta agent have a reduced risk of hepatocellular carcinoma. This may be due to inhibition of hepatitis B or to rapid progression of the disease so that death occurs before cancer develops.

Treatment - high dose alpha interferon has been successful in normalising serum aminotransferase levels and clearance of hepatitis delta virus RNA from serum in some patients

• interferon alfa inhibits HDV replication and reduces the incidence of liver-related events such as liver decompensation, hepatocellular carcinoma, liver transplant, or mortality from 8.5% per year to 3.3% per year (1)
• adverse effects from interferon alfa such as fatigue, depression, and bone marrow suppression are common

Prevention of HDV infection is by ensuring hepatitis B vaccination in patients at risk:

• vaccination for HBV infection prevents HDV infection in patients without prior HBV infection
• HBV vaccine and hepatitis B immunoglobulin (antibody) given at birth to infants born to HBV/HDV-infected mothers can prevent HBV and HDV transmission
• HBV vaccine is recommended for sexual and household contacts of people with HDV infection who have not previously received the HBV vaccine and have not had prior HBV infection
• for people with chronic HBV infection, the only preventive measure for HDV infection is avoiding contact with blood and body fluids of individuals with HDV infection

Reference:

• Negro F, Lok AS. Hepatitis D: a review. JAMA. 2023;330(24):2376-2387