Superinfection of Hepatitis B and Hepatitis D on the Horizon
Called a satellite virus, hepatitis delta virus (HDV) is making an outsized impact on liver disease and cancer worldwide. HDV only appears alongside a hepatitis B infection, and people living with HIV infection are particularly at risk of the disease.1
“It’s a very unusual virus,” says Kenneth E. Sherman, MD, PhD, a physician in medicine and the director of clinical trials development, gastroenterology division of Massachusetts General Hospital. “It can only replicate in conjunction with active hepatitis B infection. Hepatitis D is the smallest known mammalian virus.”
The virus does not code for the protein it uses to coat itself. Instead, it uses the hepatitis B excess protein to form its own coat, Sherman explains. However, people with HDV and HBV co-infection are more susceptible to severe liver disease. This leads to a faster rate of progression to cirrhosis and a significantly higher risk of developing liver cancer.
“The common scenario is a superinfection of someone who already has chronic hepatitis B infection and is producing surface antigen that becomes infected with hepatitis D,” Sherman explains. “Hepatitis D just sets up housekeeping in that ecological niche, and you have co-infection.”
Researchers are sounding the alarm about the potential of HIV patients and others having co-infection with HBV and HDV because the infection often is underdiagnosed and may be missed. Roughly one in 10 people with HIV also have hepatitis B.1
There are large laboratories that offer HDV testing. Potential treatments for HDV are in the pipeline, and it is easy to prevent both types of hepatitis.
“If you can prevent hepatitis B, then you can prevent hepatitis D,” Sherman says. “Appropriate vaccination solves the problem.”
While HBV vaccination is common in newborns and children, there remains a large part of the young adult population that missed the HBV vaccine and is at risk of infection. HDV infects people mainly through blood products, needle exposure, and sexual activity with an infected person.
Reproductive health providers should be aware of the potential HDV co-infection and suggest screening for patients with both HIV and HBV. They also suggest HBV vaccination to any patients with no record of vaccination.
It chiefly spreads through movement between regions of the world. There are pockets of HDV in the Mediterranean rim countries, as well as parts of South America and Southeast Asia.
“With net migration from ex-Mediterranean rim countries into central Europe, you end up with higher rates of hepatitis D infection in central Europe,” Sherman says. “In the U.S., immigration from South America and Asia are [a factor] ... The infectious disease community should be thinking about hepatitis D infection. There have not been strong recommendations for screening all hepatitis B people in the U.S., so it’s not generally being performed.” If rates of HBV infection increase nationwide, the chance of exposure to HDV infection also will rise, he adds.
Data from the Centers for Disease Control and Prevention (CDC) show a reduction in the number of reported acute HBV cases from 2019 to 2020, but that likely was affected by the COVID-19 pandemic causing fewer people to seek healthcare and testing.2
The CDC also reported that HBV cases were stable for a decade leading up to 2020 but had been declining since the CDC recommended routine child HBV vaccination in 1991. Now, the CDC recommends all people ages 19 to 59 years receive the hepatitis B vaccine regardless of risk factors.
- Yen DW, Soriano V, Barreiro P, Sherman KE. Triple threat: HDV, HBV, HIV coinfection. Clin Liver Dis 2023;27:955-972.
- Centers for Disease Control and Prevention. Hepatitis B surveillance 2020. Page last reviewed Aug. 19, 2022.
Called a satellite virus, hepatitis delta virus (HDV) is making an outsized impact on liver disease and cancer worldwide. HDV only appears alongside a hepatitis B infection, and people living with HIV infection are particularly at risk of the disease.
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