Global Epidemiology of Hepatitis B Virus Infection

Abstract

Hepatitis B is one of the major diseases of mankind, estimated to cause about 800,000 deaths per year mostly from liver cancer and cirrhosis. The history of the epidemiology of hepatitis B represents a landmark in the general understanding of viral infections, their distributions and their outcomes. In 2010 and 2014 resolutions of the World Health Assembly, have acknowledged at the political level that viral hepatitis is a global public health problem, ranking HBV as the 15th cause of death in all cause global mortality. The global prevalence of chronic carriage varies between 0.1 and more than 20 %. Approximately 15–40 % of chronically infected patients will develop liver cirrhosis, liver failure, or hepatocellular carcinoma and 15–25 % will ultimately die. As of today (2014), approximately 2 billion people have been infected worldwide and 240 million are chronic carriers of HBV. This represents a decrease of 31 % in HBsAg prevalence as compared to the former published figures of 350–400 million. The decrease is mainly observed in younger age groups and it is likely due to the availability of better population based data, population wide vaccination against hepatitis B in newborns, young children and adolescents, improved screening of blood products and improved safe injection procedures. However, globally an increase in both genders was observed between the 1990s and 2005 causing a change from low to a low-intermediate endemicity level in young men. It is important to note the great impact of routine infant and childhood hepatitis B immunization programs, which have caused a dramatic reduction of HBsAg carriage in immunized cohorts of children, and have led to significant decreases in HBV transmission and the occurrence of related cirrhosis and liver cancer in various populations. However, the work is not finished and a lot remains to be done to prevent new HBV infections and to cure chronically infected individuals.