What is hepatitis D?

Hepatitis D is the most severe form of viral hepatitis and only affects people who are also infected with hepatitis B. It is caused by the hepatitis delta virus (HDV), which needs the hepatitis B virus (HBV) to survive. Someone can be only infected with HDV if they are also infected with hepatitis B. An HDV/hepatitis B infection usually promotes more rapid progression to cirrhosis and liver cancer than being infected with hepatitis B alone. Conventional treatments used for hepatitis B have no effect on HDV, so it is important for hepatitis B patients to be tested for HDV so their providers can make appropriate management and treatment recommendations. 

How come hepatitis D cannot survive without hepatitis B?

In order to reproduce in liver cells, HDV requires the hepatitis B’s surface protein, called the hepatitis B surface antigen (HBsAg). HDV becomes the dominant virus, using the HBsAg from the hepatitis B virus to survive.

Is hepatitis D more dangerous than hepatitis B?

Yes, hepatitis D is the most severe form of viral hepatitis and can accelerate the risk of liver damage, cirrhosis (liver scarring) and liver cancer. Seventy percent of people with hepatitis B and D will develop serious liver damage. In contrast, only 15 to 25 percent of hepatitis B patients do.

Must you already be infected with hepatitis B in order to get hepatitis D?

Someone can acquire hepatitis D in one of two ways. A “co-infection” is when hepatitis B and hepatitis D are contracted at the same time. A “superinfection” is when someone who is already infected with chronic hepatitis B then becomes infected with hepatitis D. Most adults will clear both viruses with a “co-infection,” while those who contract hepatitis D as a “superinfection” have a 70-90% of developing a chronic infection of both viruses. The most important thing to remember is that hepatitis D cannot be contracted on its own.

 Coinfection vs superinfection chart3

How many people are infected with hepatitis D?

Globally 15-20 million people are thought to be affected, although a recent meta-analysis suggested there may be as many as 62–72 million coinfections. In the United States, approximately 20,000 people are thought to be affected.


What countries/regions is hepatitis D found?

While there is limited literature on the true global burden of HDV, it is estimated to affect 15-20 million people worldwide. HDV infections are most commonly found  in Russia, the Middle East, Mongolia, Romania, Georgia, Turkey, Pakistan, Africa, the Amazonian river basin, and some parts of India and China. Although global rates have declined in recent decades, HDV remains an enormous public health burden.

Prevalence of Hepatitis Delta in the World 

HDV epi

How is hepatitis D prevented?

Because hepatitis D requires a someone to also have hepatitis B, the best way to prevent a coinfection is by getting the hepatitis B vaccine series. Family members and sexual partners of people with hepatitis B and D should be vaccinated.

  • The hepatitis B vaccine is a series of 2 -3 shots usually given over a 6-month period and is available at a doctor’s office, health department or STD clinic. Click here to find a provider near you.

For those already infected with the hepatitis B virus, you can protect yourself from hepatitis D using protection during sex and by not sharing needles. For more prevention tips, click here.

I have chronic hepatitis B; how do I know if I also have hepatitis D?

All people living with chronic hepatitis B should be tested for hepatitis D. This is a simple blood test.

People at the highest risk for hepatitis D are those from highly endemic regions of the world including Mongolia, Romania, Russia, Georgia, Turkey, Pakistan, India, parts of Africa and the Amazonian River Basin.

If someone with chronic hepatitis B is not responding to antiviral treatment, or who has signs of liver damage even though they have a low viral load (HBV DNA below 2,000 IU/mL) should be tested. Fatty liver disease (caused by obesity) and liver damage from alcohol or environmental toxins should be ruled out as causes of liver damage.

How is hepatitis D diagnosed?

The first blood test is for the HDV antibody. This is an inexpensive, and easy-to-perform blood test. If patients test positive for the HDV antibody, which indicates they have been exposed, then the second blood test is for the HDV RNA to determine if their infection is active. A quantitative RNA test is now commercially available in the U.S., so be sure to check with your doctor about this new test. For more information about HDV RNA testing, visit the CDC website.

If the HDV antibody test is cheap and easy-to-perform, why are hepatitis B patients not routinely tested?

For many years, researchers did not think HDV existed in the U.S. As a result, there were no medical guidelines recommending hepatitis D testing. However, recent studies have found that 4 to 5% of hepatitis B patients are also infected with HDV. These findings served as a wake-up call and today liver disease experts are now drafting and promoting HDV testing guidelines for doctors.

Currently all pregnant women are tested for hepatitis B, should those who test positive also get tested for HDV?

Dr. Robert Gish, medical director of the Hepatitis B Foundation, recommends all hepatitis B-positive pregnant women should be tested for HDV if they are from a country with high rates of HDV, or if they have signs of liver damage even if they do not come from a region with high HDV rates.


I've never been tested for HDV, but my hepatitis B infection doesn't seem to be responding to entecavir or tenofovir. Does that mean I might be infected with HDV?

HDV usually suppresses hepatitis B viral replication, and becomes the dominant disease, which could be why someone may continue to have liver damage despite taking antiviral therapy for hepatitis B. Because the hepatitis B antiviral treatments have no effect on HDV, it is important for patients to be tested for a possible HDV infection so they can be managed appropriately.

How often should HDV patients see their doctors and be monitored?

Despite the absence of medical guidelines, leading experts including Dr. Robert Gish, medical director of the Hepatitis B Foundation, recommend frequent monitoring by a physician who is knowledgeable about liver diseases because HDV patients are at such high risk of cirrhosis and liver cancer. Doctors should:

  • Monitor patients’ liver enzymes (ALT/SGPT) and liver function at least every six months;
  • Perform an ultrasound of the liver and conduct a liver cancer biomarker panel (including AFP, AFPL3% and DCP) every six months; and
  • Perform viral load (HBV DNA) and HDV RNA testing every six months.
Are antivirals (entecavir and tenofovir) used to treat hepatitis B effective against HDV?

No, HDV is a different type of virus than hepatitis B so those antivirals will not stop HDV from replicating. While the two antivirals mentioned in the question can reduce hepatitis B viral DNA, they don’t eradicate the amount of hepatitis B surface antigen (HBsAg), which is what HDV requires to reproduce. Therefore, the currently available hepatitis B antivirals are not effective against HDV.

What is the current treatment for HDV?

The only proven treatment for HDV is pegylated interferon. Interferon cures HDV only 15 to 25% of the time after one year of treatment. If interferon is continued for up to five years, which has rarely been done, the cure rate can reach 40%. Once interferon clears the HDV infection, doctors place patients who continue to be infected with hepatitis B on antiviral treatment.

What is the status of HDV treatment research?

There are dozens of research efforts and biotech companies around the world working to find a cure for HDV. In addition, if a functional cure can be found for hepatitis B that makes the HBsAg disappear, then that drug will also cure HDV because it will make HBsAg unavailable for HDV replication or reproduction.

Where can I find clinical trials for HDV drugs?

There are currently 5 drugs in human clinical trials for HDV, which bring hope for more treatment options for patients. To find out about clinical trials, visit our dedicated webpage.