Makindo Medical Notes

Related Subjects: |Chronic liver disease |Liver Function Tests |Ascites Assessment and Management |Budd-Chiari syndrome |Alcoholism and Alcoholic Liver Disease |Liver Transplantation

Hepatitis D Virus (HDV) is a defective RNA virus that requires the presence of hepatitis B surface antigen (HBsAg) to replicate. It is the most severe form of viral hepatitis, accelerating progression to cirrhosis, liver failure, and hepatocellular carcinoma (HCC).

About

• 🦠 Defective RNA virus that depends on HBV for replication (cannot exist without HBsAg).
• Complications mirror HBV: cirrhosis, liver failure, and HCC – but disease progression is faster and more severe.
• HDV infection is rare in the UK but more common in IV drug users and migrants from endemic regions (Mediterranean, Middle East, Africa, Amazon basin).
• Prevention of HBV with vaccination also prevents HDV.

Aetiology & Virology

• Defective single-stranded RNA virus within a shell of HBsAg.
• Infection occurs only in those with HBV infection:
• Co-infection: Simultaneous HBV + HDV infection → usually self-limiting but can be severe acute hepatitis.
• Superinfection: HDV infection in a chronic HBV carrier → rapid progression to chronic hepatitis, cirrhosis, and high risk of HCC.

Transmission

• 🩸 Blood-borne: Needle sharing, transfusions, blood exposure.
• ❤️ Sexual contact: Especially with HBV-positive partners.
• 👶 Perinatal transmission: Less common than HBV but possible.

Clinical Presentation

• Symptoms overlap with HBV: fatigue, jaundice, nausea, dark urine, RUQ pain.
• Severe cases: Fulminant hepatitis, rapid progression to cirrhosis, decompensated liver disease.
• Superinfection: Often presents with sudden worsening in a patient with known chronic HBV.

Investigations

• HBsAg: Must be positive for HDV diagnosis.
• Anti-HDV IgM/IgG: Indicates current or past infection.
• HDV RNA: Confirms active viral replication.
• Liver function tests: Raised ALT, AST, bilirubin; falling albumin with chronicity.
• Imaging/biopsy: To assess for cirrhosis or HCC if advanced disease suspected.

Management

• 💉 Pegylated Interferon-alpha: Mainstay, but response is limited and relapse is common.
• 💊 HBV antivirals (e.g. Tenofovir, Entecavir): Suppress HBV, reducing HBsAg availability for HDV replication.
• 🧪 New agents: Bulevirtide (entry inhibitor) licensed in the EU for chronic HDV with promising results.
• 🩺 Liver transplantation: For end-stage disease or fulminant liver failure.

Prevention

• 💉 HBV vaccination: Prevents both HBV and HDV.
• Safe needle practices and safe sex education.
• Screen high-risk groups (IVDU, migrants from endemic areas) for HBV and HDV co-infection.