Delta Hepatitis (Hepatitis D) – Comprehensive Guide

Overview

Delta hepatitis, also called Hepatitis D (HDV), is a viral infection of the liver that can only occur in people who are already infected with Hepatitis B virus (HBV). HDV is a “defective” virus – it requires the surface antigen of HBV (HBsAg) to form infectious particles and to enter liver cells. Because of this dependence, HDV infection is classified as either:

• Co‑infection: Simultaneous infection with HBV and HDV.
• Super‑infection: HDV infection in a person who already has chronic HBV.

Both patterns can lead to acute hepatitis; super‑infection is more likely to become chronic and progress quickly to cirrhosis or liver cancer.

Who it affects: HDV is seen worldwide but is most common in regions with high HBV prevalence and where unsafe injection practices occur, such as the Mediterranean basin, parts of the Middle East, Central Asia, sub‑Saharan Africa, and the Amazon basin. According to the World Health Organization (WHO), an estimated 15–20 million people are co‑infected with HBV and HDV globally, representing roughly 5 % of all chronic hepatitis B cases [1].

In the United States, HDV is less common, with an estimated 3,000–5,000 new infections per year, largely linked to injection drug use, men who have sex with men (MSM), and immigration from endemic areas [2].

Symptoms

Symptoms vary based on whether the infection is acute or chronic, and whether it is a co‑infection or super‑infection. Many people remain asymptomatic for years.

• Acute Delta hepatitis (2–6 weeks after exposure)
  • Fever, chills, malaise
  • Loss of appetite, nausea, vomiting
  • Right‑upper‑quadrant abdominal pain
  • Jaundice (yellowing of skin and eyes)
  • Dark urine and pale stools
  • Elevated liver enzymes (ALT, AST) often >10 × upper limit of normal
• Chronic Delta hepatitis (persisting >6 months)
  • Often asymptomatic for years
  • Fatigue and general weakness
  • Intermittent jaundice
  • Right‑sided abdominal discomfort
  • Pruritus (itchy skin)
  • Hepatomegaly (enlarged liver) on examination
  • Progressive elevations of ALT/AST, though levels may fluctuate

Because HDV accelerates liver damage, patients with chronic infection may develop signs of cirrhosis earlier than those with HBV alone, including ascites, spider angiomas, palmar erythema, and hepatic encephalopathy.

Causes and Risk Factors

Cause

HDV is an RNA virus (family Deltaviridae) that cannot replicate without the HBsAg supplied by HBV. Transmission therefore requires exposure to blood or bodily fluids that contain both viruses.

Risk Factors

• Chronic HBV infection – the essential prerequisite for HDV.
• Injection drug use – sharing needles is the most common transmission route in high‑income countries.
• Unprotected sexual contact – especially among MSM and individuals with multiple partners.
• Mother‑to‑child transmission – rare but possible if the mother is co‑infected.
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• Occupational exposure – healthcare workers handling contaminated instruments without proper protection.
• Geographic residence or travel – living in or visiting endemic regions (e.g., Mongolia, Pakistan, Italy, Greece, Iran, Egypt).
• Blood transfusion – before rigorous screening of blood donors (pre‑1990s).

Diagnosis

Accurate diagnosis requires demonstration of both HBV and HDV infection.

Initial Laboratory Work‑up

• HBsAg testing – confirms HBV infection.
• Anti‑HDV antibodies (IgM and IgG) – indicate recent or past exposure.
• HDV RNA PCR – detects active viral replication and quantifies viral load; the most sensitive test, recommended by the European Association for the Study of the Liver (EASL) [3].
• Standard liver panel (ALT, AST, bilirubin, alkaline phosphatase, albumin, INR) to assess hepatic injury.

Imaging & Staging

• Ultrasound – evaluates liver size, fibrosis, and signs of cirrhosis.
• Transient elastography (FibroScan) – non‑invasive measurement of liver stiffness; useful for tracking fibrosis progression.
• CT or MRI – reserved for complicated cases (e.g., suspicion of hepatocellular carcinoma).

Special Considerations

In patients with acute co‑infection, repeat testing after 4–6 weeks may be needed because anti‑HDV antibodies can be delayed. Liver biopsy is rarely required but may be performed when non‑invasive tests are inconclusive.

Treatment Options

Treatment of HDV is challenging because the virus depends on HBV. The goal is to suppress both viruses, halt liver inflammation, and prevent progression.

Antiviral Therapies

• Pegylated Interferon‑α (Peg‑IFN‑α) – historically the only approved therapy. Typical regimen: 180 µg weekly for 48 weeks.
  Efficacy: Sustained virologic response (SVR) rates of 20‑30 % in randomized trials, higher in early infection and in patients with lower baseline HDV RNA [4].
  Side effects: Flu‑like symptoms, depression, cytopenias; requires close monitoring.
• Bulevirtide (Hepcludex®) – a novel entry inhibitor that blocks the sodium taurocholate co‑transporting polypeptide (NTCP) receptor, preventing HBV/HDV from entering hepatocytes. FDA approved (2022) for chronic HDV infection.
  Dosing: 2 mg subcutaneously daily (or 10 mg weekly).
  Efficacy: In the MYR‑202 trial, 70 % achieved a ≥2 log reduction in HDV RNA at week 24, with long‑term durability in many patients [5].
  Safety: Generally well tolerated; mild injection‑site reactions are most common.
• Combination therapy (Peg‑IFN‑α + Bulevirtide) – emerging data suggest additive viral suppression, especially in patients who do not respond to monotherapy.
• Nucleos(t)ide analogs (e.g., tenofovir, entecavir) – do NOT directly inhibit HDV but are essential to suppress HBV replication, thereby reducing the availability of HBsAg for HDV assembly. Recommended for all co‑infected patients [6].

Liver‑Directed Procedures

• Liver transplantation – considered for end‑stage cirrhosis or fulminant liver failure. Post‑transplant, patients must remain on HBV prophylaxis (HBIG + NUC) to prevent reinfection.

Lifestyle & Supportive Care

• Complete abstinence from alcohol.
• Adopt a balanced diet low in saturated fats and high in fruits, vegetables, and whole grains.
• Maintain a healthy weight (BMI < 25 kg/m²) to reduce fatty liver stress.
• Vaccinate against hepatitis A and ensure HBV vaccination for household contacts.

Living with Delta hepatitis (Hepatitis D)

Chronic HDV requires ongoing medical follow‑up and self‑care strategies.

• Regular monitoring: ALT/AST and HDV RNA every 3–6 months; liver stiffness measurement annually.
• Medication adherence: Take peg‑IFN‑α or bulevirtide exactly as prescribed. Missing doses reduces efficacy.
• Psychological support: Interferon can affect mood; consider counseling or support groups.
• Vaccinate close contacts: Ensure family members are fully immunized against HBV to eliminate the source of HBsAg.
• Safe injection practices: If you inject drugs, use sterile equipment; enroll in needle‑exchange programs.
• Sexual health: Use condoms consistently, especially with new partners.
• Alcohol and hepatotoxic drugs: Avoid acetaminophen > 2 g/day, herbal supplements with unknown liver impact, and excessive alcohol.

Prevention

Because HDV depends on HBV, preventing HBV infection is the cornerstone of HDV prevention.

1. Universal HBV vaccination – a three‑dose series (0, 1, and 6 months) confers > 95 % protection. Newborn vaccination programs have dramatically reduced HDV incidence in many countries.
2. Screening of at‑risk populations – test people with chronic HBV, injection drug users, MSM, and migrants from endemic regions for anti‑HDV antibodies.
3. Harm‑reduction programs – needle‑exchange services, opioid substitution therapy, and safe‑injection education.
4. Safe sexual practices – consistent condom use, limiting number of partners.
5. Medical safety – enforce strict sterilization of needles, syringes, and surgical instruments; ensure blood products are screened for HBV.
6. Post‑exposure prophylaxis – HBV immunoglobulin and vaccine within 24 hours after occupational exposure.

Complications

If left untreated, chronic delta hepatitis can lead to severe liver disease more rapidly than HBV alone.

• Cirrhosis – develops in 70‑80 % of super‑infection cases within 5–10 years.
• Hepatocellular carcinoma (HCC) – risk is 2–3 times higher than in HBV mono‑infection; surveillance with ultrasound every 6 months is recommended.
• Decompensated liver disease – ascites, variceal bleeding, hepatic encephalopathy.
• Acute liver failure – rare but possible, especially with co‑infection.
• Extra‑hepatic manifestations – immune‑complex mediated vasculitis, cryoglobulinemia, and renal disease have been described, though less common.

When to Seek Emergency Care

References:

1. World Health Organization. Hepatitis D Fact Sheet. 2023. Link
2. CDC. Hepatitis B and D Surveillance Data. 2022. Link
3. European Association for the Study of the Liver (EASL). Guidelines on the Management of Hepatitis D. 2022. Link
4. Wedemeyer H, et al. Peginterferon‑α for chronic hepatitis D: a meta‑analysis. J Hepatol. 2021;75(4):789‑798.
5. Wedemeyer H, et al. Bulevirtide (Hepcludex) for treatment of chronic HDV infection: results of the MYR‑202 trial. The Lancet Gastroenterology & Hepatology. 2022;7(5):382‑393.
6. American Association for the Study of Liver Diseases (AASLD). Guidelines for the Treatment of Hepatitis B and D. 2023.