Hepatitis D Virus Update

Hepatitis D virus (HDV), also known as hepatitis delta virus, is a defective virus that requires hepatitis B virus (HBV) to multiply and cause disease in humans.

HDV seroprevalence is estimated at 0.16% in the general population and 4.5% (11-13 million) in HBV carriers. The prevalence of HDV infection is decreasing globally, in parallel with the decrease in HBV, which the implementation of a universal vaccination program has caused.

HDV is transmitted parenterally (needle stick, intravenous drug use, transfusion, etc.) and through contact with body fluids, similar to HBV. Horizontal (within-family) spread is usually seen in highly endemic areas, and sexual transmission has also been reported. HDV can lead to two distinct clinical conditions: coinfection and superinfection.

Coinfection occurs when acute HBV and acute HDV infections co-occur after simultaneous exposure to both viruses. In more than 90% of cases, HBV/HDV coinfection results in viral clearance.

Superinfection occurs when HDV is transmitted to a chronic HBV-infected individual. Superinfection can cause severe acute hepatitis, and spontaneous clearance occurs in only a tiny proportion of patients. Approximately 80% of cases progress to chronic HDV infection. Chronic HDV infection is considered the most serious and lethal form of viral hepatitis because of its rapid progression to liver cirrhosis and hepatocellular carcinoma.

HDV is diagnosed by detecting high levels of anti-HDV IgG or serum HDV RNA.

The ideal goal of antiviral therapy in chronic HDV is to eliminate both HDV and HBV and prevent long-term sequelae of the infection. However, since there is no antiviral under ideal conditions, patients have been treated with pegylated interferon-alpha (PEG-IFNα) since the 1980s until recently. In July 2020, bulevirtide (BLV) became the first officially approved HDV drug to treat chronic HDV, and many agents are in the clinical development phase.

Until effective and safe new treatments become available, the most appropriate approach will be to develop prevention and HDV screening strategies with HBV vaccination.

Keywords: HDV, Hepatitis delta virus, HDV coinfection, HDV superinfection, HBV.

Dr. Muhammed Bekçibaşı graduated from Dicle University Faculty of Medicine in 2008 and completed his specialization in the Department of Infectious Diseases and Clinical Microbiology at Dicle University Faculty of Medicine in 2014. He has numerous scientific studies published in national and international journals in the field of infectious diseases and clinical microbiology. He is currently actively serving his patients at the Department of Infectious Diseases and Clinical Microbiology at the Health Sciences University Gazi Yaşargil Training and Research Hospital