Control and prevention of hepatitis B virus infection

Abstract

Hepatitis B is a disease of global importance with an estimated nearly 350 million persistent carriers of hepatitis B virus (HBV) worldwide (WHO Press Release, 1992). Of HBV carriers with a life expectancy of more than 30 years, 25% to 30% would die from complications of hepatitis B and those who live with the disease often suffer for decades (Can. Dis. Wkly. Rep. 1991; Krahn and Detsky, 1992). HBV, the single most important cause of persistent viral carriage on a global basis, is responsible for a high proportion of the world’s cases of cirrhosis and involved in the etiology of hepatocellular carcinoma. Primary liver cancer is noted to be one of the main causes of deaths from cancer among men in many African, Asian and Pacific basin countries. Cirrhosis and primary liver cancer, caused by HBV infection, possibly account for one to two million deaths per year (WHO Press Release, 1992). It is second only to tobacco smoking as a cause of cancer mortality (WHO Report, 1983). The serious consequences of HBV are a result of development of the persistent viral carrier state which has been estimated to occur between 70% and 90% of acute HBV infections in infancy and declining to between 6% and 10% of infections occurring after the 6th year on life (Maynard et al., 1988). Geographic patterns of HBV prevalence have been noted to vary greatly worldwide from areas of low endemicity, with less than 1% of adults as chronic HBV carriers and less than 10% of the adult population who would probably experience infection, to areas of intermediate and high endemicity with chronic carrier rates of 2%–15% in adults and 30%–100% of the population experiencing infection. Currently, nearly 4 billion individuals reside in areas of the world where hepatitis B virus infection is of intermediate or high endemicity (Maynard et al., 1988).