Epidemiology and diagnosis of hepatitis D virus

Epidemiology Pattern, Prevalent Genotype Distribution, Fighting Stigma and Control Options for Hepatitis D in Bulgaria and Other European Countries

Hepatitis D virus (HDV) is a satellite virus that causes the most aggressive form of all viral hepatitis in individuals already infected with HBV (hepatitis B virus). In recent years, there has been a negative trend towards an increase in the prevalence of chronic hepatitis D in Europe, especially among immigrant populations coming from regions endemic for the virus. The aim of this review is to analyse the current epidemiology of chronic HDV, routes of transmission, prevalent genotype, its management, prevention, fighting stigma and options for viral control in European countries, such as Bulgaria.

An update on the management of chronic hepatitis D

Hepatitis D virus (HDV) infection is associated with severe liver-related morbidity and mortality. The prevalence of HDV is rising especially among people who abuse drugs and immigrants from endemic areas. Reliable diagnostic assays with enhanced sensitivity and specificity are essential for screening at-risk populations. Until recently, interferon has been the only treatment for hepatitis D. Its efficacy is, however, limited and it is associated with significant side effects. A number of novel antiviral agents that target various stages of the HDV life cycle show promising results. They are currently in different phases of clinical development. This review focuses on the changing epidemiology, novel therapeutic agents, and updated management of chronic hepatitis delta.

The impact of vaccination and antiviral therapy on hepatitis B and hepatitis D epidemiology

The major cause of liver cancer around the globe is hepatitis B virus (HBV), which also contributes to a large number of deaths due to liver failure alone. Hepatitis delta virus (HDV) is as potentially alarming as HBV since life threatening cases are 10 times more likely with HBV-HDV dual infection compared to HBV monoinfection. So far, there is no established effective treatment against HDV and the only preventive action suggested by the World Health Organization is to introduce HBV vaccination for children immediately after birth (newborns) and thus reduce the available pool for HDV infection. Here the main objective is to understand the complex dynamics of HBV-HDV infection in a human population that can inform public health policy makers on the level of different preventive measures required to eliminate HBV and HDV infections. Model simulations suggest that HBV vertical transmission and HBV vaccination rates for newborns are instrumental in determining HBV and HDV prevalence. A decrease in HBV prevalence is observed as vaccination coverage increases and it is possible to eradicate both HBV and HDV using high vaccination coverage of ≥80% in the long term. We further found that HDV presence results in lower HBV prevalence. An application of our model to China revealed that vaccinating every newborn in China will further prevent 1.69 million new infections by 2028 as compared to the current 90% vaccination coverage. Although, higher vaccination coverage of newborns should eliminate both HBV and HDV over a long time period, any short term strategy to eradicate HDV must include additional preventive measures such as HBV adult vaccination. Implementation of HBV adult vaccination programs at a rate of 10% per year over 15 years will further prevent 39 thousand new HDV infections in China by 2028 as compared to HBV vaccination programs solely for newborns.