What is Hepatitis D? Is it dangerous? Causes and symptoms. Is it really caused by Hepatitis B? 2025

Hepatitis D (also known as HDV or Hepatitis Delta Virus) is one of the most severe and complex forms of viral hepatitis affecting the human liver. What makes HDV unique is that it cannot cause infection on its own—it depends entirely on the Hepatitis B virus (HBV) to replicate and spread within the human body.

This article explores everything you need to know about Hepatitis D: from its nature and transmission, to symptoms, diagnosis, treatment, and practical prevention strategies. All information is based on reputable medical sources—empowering you to make well-informed decisions for your liver health.

What is Hepatitis D?

Hepatitis D virus (HDV) is a unique virus that causes inflammation of the liver. Unlike other hepatitis viruses, HDV cannot infect or replicate on its own—it requires the presence of the hepatitis B virus (HBV) to become infectious.

This virus is classified as a defective or satellite virus because it relies on HBV to provide the surface proteins needed to assemble and release new viral particles from liver cells. As a result, HDV infection occurs only in individuals who are already infected with HBV, either through co-infection (simultaneous infection with HBV and HDV) or superinfection (HDV infection after chronic HBV infection).

HDV infection tends to be more severe than HBV alone. It is associated with a higher risk of acute liver failure, rapid progression to liver cirrhosis, and an increased chance of developing liver cancer.

Alternative medical names

• Hepatitis Delta Virus (HDV)
• Delta Agent

Classification

HDV is considered a “defective virus” because it cannot replicate without a helper virus. In this case, the helper virus is Hepatitis B virus (HBV).

How is Hepatitis D transmitted?

Hepatitis D virus (HDV) can only be transmitted in individuals who are already infected with the hepatitis B virus (HBV). HDV depends on HBV’s surface antigens to enter liver cells and replicate.

HDV is transmitted in similar ways to HBV, including:

• Exposure to infected blood or bodily fluids (e.g., sharing needles or contact with open wounds)
• Unprotected sexual contact with an infected person
• Blood transfusions or organ transplants without proper screening
• From mother to child during childbirth (less common)

People with HBV infection, especially those with high-risk behaviors such as intravenous drug use, should be screened for HDV to detect co-infection early.

Can you get Hepatitis D without Hepatitis B?

No—you cannot get infected with Hepatitis D unless you already have Hepatitis B (HBV).
HDV requires HBV’s surface proteins to enter liver cells and replicate. Without HBV, HDV cannot become infectious.

There are two primary types of HDV infection:

• Co-infection: Simultaneous infection with both HBV and HDV
• Superinfection: HDV infection in someone who already has chronic HBV

Superinfection is typically more severe than co-infection and is more likely to lead to chronic liver disease, cirrhosis, or liver cancer over time.

In summary, Hepatitis D cannot occur without Hepatitis B as a helper virus.

Symptoms of Hepatitis D

The symptoms of Hepatitis D (HDV) vary depending on the type of infection:

Co-infection (HBV and HDV at the same time)

When both viruses are contracted together, symptoms are similar to other acute hepatitis infections, such as:

• Fatigue and loss of appetite
• Nausea and vomiting
• Pain in the upper right abdomen
• Jaundice (yellowing of skin and eyes)
• Dark urine and pale stools

In some cases, co-infection can lead to acute liver failure, especially in immunocompromised individuals.

Superinfection (HDV in someone already infected with HBV)

In those with chronic HBV, HDV superinfection is often more severe and long-lasting. Common signs include:

• Chronic liver inflammation
• Liver enlargement or tenderness
• Persistently abnormal liver enzymes
• High risk of liver cirrhosis and hepatocellular carcinoma

Symptoms may not be obvious in the early stages, so high-risk individuals should be tested even if they feel well.

How is Hepatitis D diagnosed?

Testing for Hepatitis D (HDV) is performed only in individuals who test positive for Hepatitis B (HBsAg) since HDV requires HBV to infect and replicate.

Diagnostic steps

1. Hepatitis B surface antigen (HBsAg) test: A positive result indicates the presence of HBV, making HDV testing necessary.
2. Anti-HDV antibody test: This detects antibodies produced in response to HDV infection.
3. HDV RNA test (via PCR): Confirms active infection by detecting the virus’s genetic material in the blood and can quantify the viral load.
4. Liver function tests (LFTs): Includes ALT, AST, and bilirubin levels to evaluate liver inflammation or damage.

HDV testing is not routinely performed for all HBV-positive patients. Physicians may order it based on risk factors, symptoms, or abnormal liver test results.

How is Hepatitis D treated?

Treating Hepatitis D (HDV) is medically challenging because no antiviral therapy currently exists that can directly eliminate HDV—unlike with Hepatitis C.

Current treatment strategies

1. Pegylated interferon-alpha (Peg-IFN): The primary treatment used to stimulate the immune response to suppress HDV replication.
   • Typical duration: 48 weeks
   • Treatment response varies by individual, and relapse may occur after discontinuation.
2. Regular liver function monitoring: Patients should undergo periodic liver enzyme tests and viral load assessments to track disease progression.
3. Clinical trial participation: Since curative treatments are limited, clinical studies may offer access to promising new drugs like Bulevirtide, which has shown positive preliminary results in some cases.
4. Supportive care: Patients with complications such as cirrhosis may require additional treatment, including management of ascites or liver transplantation in advanced liver failure.

As of now, no HDV-specific medication is officially approved in many countries, including Thailand. Treatment decisions are individualized and managed by specialized healthcare providers.

Is there a vaccine for Hepatitis D?

There is currently no vaccine that directly protects against Hepatitis D (HDV). However, HDV can be effectively prevented by getting vaccinated against Hepatitis B (HBV)—because HDV cannot infect people who are not already infected with HBV.

How HBV vaccination protects against HDV

• HDV depends on HBV: Without HBV, HDV cannot survive or replicate
• The HBV vaccine is highly effective: Preventing HBV infection indirectly prevents HDV as well

Who should get the HBV vaccine?

• Newborns (ideally within 24 hours of birth)
• Healthcare workers
• Individuals at high risk (e.g., those who share needles or have unprotected sex)
• Patients requiring frequent blood transfusions

If you’ve completed the full HBV vaccination schedule and developed immunity, you are also protected against HDV infection.

Who is at risk of Hepatitis D?

People at risk of Hepatitis D (HDV) infection are those who are already infected with Hepatitis B (HBV) or engage in behaviors that increase their risk of acquiring HBV—since HDV depends on HBV to infect.

High-risk groups

• People with chronic HBV infection: Especially those with weakened immunity or existing liver conditions
• People who inject drugs and share needles
• Those with unprotected sex: Particularly with multiple partners or a history of STIs
• Recipients of unscreened blood or organ transplants
• Household contacts of people with HBV or HDV infection

Although HDV is less common than HBV or HCV, it’s more aggressive when co-infection occurs. Understanding risk factors and getting screened can help prevent serious complications.

How to prevent Hepatitis D

Although no vaccine exists specifically for Hepatitis D (HDV), it can be effectively prevented by avoiding Hepatitis B (HBV) infection and minimizing high-risk behaviors.

Recommended prevention methods

1. Get vaccinated against Hepatitis B: This is the most effective way to prevent HDV since it depends on HBV to infect.
2. Do not share needles or personal sharp objects: Includes razors, nail clippers, or anything that could be contaminated with blood.
3. Practice safe sex: Consistently use condoms, especially with multiple or new partners.
4. Ensure proper blood and organ screening: Only accept transfusions or transplants that have been thoroughly screened for HBV and HDV.
5. Avoid contact with blood or bodily fluids of infected individuals: Especially if you have open wounds or damaged skin.

Since HDV cannot exist without HBV, preventing HBV is key to avoiding HDV infection.

How dangerous is Hepatitis D?

Hepatitis D (HDV) is considered the most severe form of viral hepatitis, particularly in cases of superinfection—when someone with chronic Hepatitis B (HBV) acquires HDV.

Health risks associated with HDV

• Severe acute hepatitis: Can develop within weeks, especially in people with weakened immune systems
• Rapid progression to cirrhosis: HDV accelerates liver cell damage, often leading to cirrhosis within a few years
• Liver cancer: Those co-infected with HBV and HDV have a higher risk of developing hepatocellular carcinoma
• Low treatment response: HDV is harder to treat compared to other hepatitis viruses and often becomes chronic

Because of these risks, individuals infected with HDV require close medical monitoring and specialized care to manage long-term complications.

How is Hepatitis D different from Hepatitis C?

Hepatitis D (HDV) and Hepatitis C (HCV) are distinct viruses that both affect the liver, but they differ significantly in virology, transmission, and treatment approaches.

Comparison Table: HDV vs HCV

In summary:

• HDV is more aggressive but less common
• HCV is more prevalent and has a high cure rate with modern treatments

Where can you get tested for Hepatitis D?

Testing for Hepatitis D (HDV) is only conducted in individuals already diagnosed with Hepatitis B and who are considered high risk. HDV testing requires specialized laboratory tools and clinical interpretation by a healthcare professional.

Facilities that offer HDV testing

• Major public hospitals: University or referral hospitals with liver or infectious disease departments
• Private hospitals: Especially those with comprehensive GI or liver care centers
• Liver specialty clinics: Supervised by hepatologists who can request HDV RNA or anti-HDV testing
• Tropical medicine clinics: For patients with exposure from high-risk regions or travel history

Pre-testing considerations

• Always get tested for HBsAg first—HDV cannot infect without HBV
• Avoid using over-the-counter HDV tests, as they often lack molecular accuracy
• Consult a doctor to assess risk and determine the appropriate testing method

Frequently Asked Questions About Hepatitis D

1. If I’ve had the Hepatitis B vaccine, can I still get Hepatitis D?

No. If you are immune to HBV, you cannot get HDV since it requires HBV to infect.

2. Can Hepatitis D be cured?

There’s currently no guaranteed cure, but pegylated interferon may control the infection in some cases. Regular monitoring is essential.

3. Is Hepatitis D contagious?

Yes. It can be transmitted via blood or sexual contact—but only if the person exposed is not immune to Hepatitis B.

4. Do all people with HBV need to be tested for HDV?

Not necessarily. Doctors may recommend testing for high-risk individuals or those showing unexplained liver symptoms.

5. Is Hepatitis D more dangerous than Hepatitis B?

Yes. HDV is generally more severe, especially in superinfection, and can lead to liver failure or cirrhosis faster than HBV alone.

Conclusion

Though less common than Hepatitis B or C, Hepatitis D can lead to more severe liver complications when infection occurs—especially in people already living with HBV. Understanding the virus in detail—from its mechanism to prevention—is critical, particularly for high-risk individuals.

Getting vaccinated against HBV and maintaining safe health practices remain the best lines of defense against HDV and its long-term complications.

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