Epidemiologists Discover a Silent Epidemic of Hepatitis

RUDN University epidemiologists have reconstructed the history of  hepatitis B and D viruses evolution in Yakutia (Russia). The investigation has established the course of evolution over the past fifteen hundred years. It turned out that a silent epidemic of hepatitis D continues in the region, and measures must be taken to stop it. Results published in BMC Infectious diseases .

In many regions, hepatitis B (HBV) and hepatitis D (HDV) viruses remain common despite the existence of a hepatitis B vaccine. There are 10 known HBV genotypes. All of them have their own geography of distribution. Fewer genotypes are known for HDV and the worldwide distribution is less heterogeneous. Little is known about the relationship between HDV and HBV, although many patients are infected with both viruses at the same time. RUDN University epidemiologists tried to establish the details of the joint evolution of HDV and HBV using the example of Yakutia, the largest subject of Russia.

“We established how the evolution of HBV and HDV took place in Yakutia, the region of Russia that suffered the most from hepatitis. The reasons for the unusual distribution of HBV and HDV genotypes in Yakutia, as well as the possible relationship between the genotypes of the two viruses, have not been studied. Our goal was to try to understand what mechanisms could lead to the unusual structure of viral genotypes. In addition, we decided to identify current distribution trends,” said Anastasia Karlsen, researcher at the Scientific and Educational Resource Center for High-Performance Methods of Genomic Analysis, RUDN University.

The epidemiologists selected 140 HBV patients and 59 patients co-infected with HBV and HDV. Together with these data, the authors used 327 viral genomes from the data bank. All these data were studied by RUDN University epidemiologists using phylogenetic analysis. It allows one to identify the evolutionary relationship of the two viruses.

HBV and HDV viruses have evolved over the past 1,500 years. The variant of HBV, which is now most common in Russia, probably appeared 1253 years ago and has common ancestors with viruses now common in India, China, Pakistan and Iran. The history of HDV in Yakutia is much shorter. In this region, the virus appeared only 180 years ago. One of its variants spread only in Yakutia and was not seen anywhere else. At the same time, the dynamics of HBV is stable, but HDV has become more active in recent years. This suggests that a “silent” epidemic of hepatitis D has begun. Therefore, it is necessary to take measures – for example, to introduce mandatory screening of patients for HDV.

“The recent increase in HDV dynamics against the backdrop of stable HBV suggests a silent HDV epidemic. This is despite a very low reported incidence. Although current HBV prevention measures are effective enough to prevent new HBV infections, they are not enough to control the HDV epidemic. Expanded screening programs and mandatory testing for HDV are needed for all patients with hepatitis B,” said Karen Kyuregyan, Leading Researcher Scientific and Educational Resource Center for High-Performance Methods of Genomic Analysis, RUDN University.