[Viral hepatitis A to E: prevalence, pathogen characteristics, and pathogenesis]

Viral hepatitis is characterized as an acute or chronic inflammation of the liver induced by an infection with certain viruses. At present, around 325 million humans suffer from the chronic form of the disease worldwide. Each year, about 1.6 million people die as a result of viral hepatitis. The causative agents, hepatitis viruses, are subdivided into five groups of pathogens, which are denoted with the letters A to E (HAV to HEV). These differ from each other with respect to phylogeny, transmission, epidemiology, host-specificity, life cycle, structure, and distinct aspects of pathogenesis.The strictly human-pathogenic HAV, a member of the Picornaviridae family, mostly induces acute hepatitis and displays a dominant spread over the Global South. The Hepeviridae-affiliated HEV shows a similar epidemiology, yet spreads further into industrialized countries due to its zoonotic potential. Furthermore, HEV is defined by the capability of inducing chronic hepatitis. This course of disease is also found in a more pronounced manner for the globally prevalent HBV (Hepadnaviridae) and its satellite virus HDV (Kolmioviridae), which further increases their carcinogenic potential. Lastly, a worldwide distribution is similarly described for HCV (Flaviviridae), which displays a high risk of chronifications and therefore a highly increased carcinogenic potential.The aforementioned pathogens differ with respect to their properties and life cycles. Thus, a differentiated look on epidemiology, diagnostic procedures, and disease prevention is required. Despite the presence of therapies, in some cases even a vaccine, there is an urgent need for advances in research on these aspects, especially for poverty-related pathogens.