No, Hepatitis D Cannot Occur Without Hepatitis B
Hepatitis D virus (HDV) is absolutely dependent on hepatitis B virus (HBV) for infection and cannot exist without concurrent HBV infection. HDV is a defective virus that requires HBV surface antigen (HBsAg) to enter hepatocytes, replicate productively, and transmit between individuals 1.
Why HDV Requires HBV
HDV borrows all three HBV envelope proteins (HBsAg) to both enter and exit hepatocytes, making it fundamentally incapable of establishing infection without HBV 1.
HDV is classified as a "satellite virus" or "defective virus" that depends entirely on HBV for production of envelope proteins necessary for viral assembly and transmission 1, 2.
HDV can only be acquired through two mechanisms, both requiring HBV presence 1, 2:
- Coinfection: Simultaneous infection with both HBV and HDV
- Superinfection: New HDV infection in someone already chronically infected with HBV
Important Clinical Distinction
While HDV replication itself is independent of HBV once inside the hepatocyte, the virus still requires HBsAg for entry and egress, meaning productive infection cannot be sustained without HBV 1.
All patients with HDV infection will test positive for HBsAg (hepatitis B surface antigen), as this is the obligatory marker of HBV infection that HDV requires 1.
Screening Implications
All HBsAg-positive patients should be screened for HDV using anti-HDV antibodies or HDV RNA testing, particularly those from endemic regions or with injection drug use history 1.
HDV testing is only indicated in HBsAg-positive individuals, as HDV cannot exist in HBsAg-negative persons 1.
Clinical Outcomes Based on Infection Pattern
Acute HBV/HDV coinfection rarely progresses to chronic infection (only ~2-5% of cases), though it causes more severe acute hepatitis with higher mortality than HBV alone 1, 3, 2.
HDV superinfection of an HBV carrier results in chronic infection in >90% of cases and leads to more aggressive liver disease with rapid progression to cirrhosis 1, 3, 2.