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.
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.
Yes, HDV causes an accelerated rate of liver damage, and leads to cirrhosis (liver scarring) and liver cancer more rapidly. Seventy percent of people with HDV will develop serious liver damage. In contrast, only 15 to 25 percent of hepatitis B patients do.
Someone can acquire HDV in one of two ways. A “coinfection” is when hepatitis B and HDV are contracted at the same time. A “superinfection” is when someone who is already infected with hepatitis B then becomes infected with HDV. Most adults will clear both viruses with a “coinfection,” while those who contract HDV as a “superinfection” have a 70-90% of developing a chronic HDV/hepatitis B infection. The most important thing to remember is that HDV cannot be contracted without an existing hepatitis B infection.
Hepatitis D infects about 15-20 million people globally, and about 20,000 people in the U.S.
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 is a bloodborne infection spread through direct contact with HDV-infected blood and body fluids. It is spread:
- During childbirth -- from infected mother to newborn;
- Sexually; and
- Through use of contaminated or improperly-sterilized medical devices, including syringes, surgical and dental devices and knives used for scarification.
When deciding whether to test for HDV, doctors consider where your family is from (country of origin) and your medical condition. This is a simple blood test.
Country of origin: Anyone with chronic hepatitis B who comes from Sub-Saharan Africa, China, Russia, Middle East, Mongolia, Romania, Georgia, Turkey, Pakistan and the Amazonian River Basin should be tested for HDV.
Medical condition: Anyone with chronic hepatitis B who 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 before testing for HDV.
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.
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.
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.
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.
Yes, these two shots are very important to protecting a newborn from hepatitis B and HDV infections.
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.
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.
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.
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.