Hepatitis B virus epidemiology, disease burden, treatment, and current and emerging prevention and control measures

Abstract

Hepatitis B virus (HBV) infection is a serious global health problem, with 2 billion people infected worldwide, and 350 million suffering from chronic HBV infection. The 10th leading cause of death worldwide, HBV infections result in 500 000 to 1.2 million deaths per year caused by chronic hepatitis, cirrhosis, and hepatocellular carcinoma; the last accounts for 320 000 deaths per year. In Western countries, the disease is relatively rare and acquired primarily in adulthood, whereas in Asia and most of Africa, chronic HBV infection is common and usually acquired perinatally or in childhood. More efficacious treatments, mass immunization programs, and safe injection techniques are essential for eliminating HBV infection and reducing global HBV-related morbidity and mortality. Safe and effective vaccines against HBV infection have been available since 1982. The implementation of mass immunization programs, which have been recommended by the World Health Organization since 1991, have dramatically decreased the incidence of HBV infection among infants, children, and adolescents in many countries. However, not all countries have adopted these recommendations and there remains a large number of persons that were infected with HBV prior to the implementation of immunization programs. Antiviral treatment is the only way to reduce morbidity and mortality from chronic HBV infection. Conventional interferon alfa and lamivudine have been the primary treatments to date. Conventional interferon alfa produces a durable response in a moderate proportion of patients but has undesirable side-effects and must be administered subcutaneously three times per week. Lamivudine also produces a response in a modest proportion of patients and causes few side-effects. However, prolonged treatment is often necessary to prevent relapse on cessation of therapy, and continuous treatment can lead to the development of lamivudine resistance. Promising emerging new treatments include adefovir, entecavir and peginterferon alfa-2a (40 kDa).

Clearance of hepatitis B surface antigen and risk of hepatocellular carcinoma in a cohort chronically infected with hepatitis B virus

“…1 Perinatal or horizontal infection early in childhood is the main route of HBV transmission. After acute hepatitis B, most persons achieve complete immune clearance of the virus, yielding lifelong immunity.…”

Care delivery and outcomes among US veterans with hepatitis B: A national cohort study

“…The mean proportion of time high-risk carriers were adherent to annual imaging was 0.19 (SD 5 0.29), and for biannual imaging it was 0.12 (SD 5 0.25); both were significantly higher for those in specialty care. Figure 1 summarizes the hepatitis B treatment cascade within the VHA stratified by time period predating the most recent AASLD guidelines (era 1,[2003][2004][2005][2006][2007][2008][2009]) and after the guideline release (era 2, 2010-2012). Overall, rates of ALT testing were high, while DNA testing increased from era 1 to era 2.…”

“…In the United States, the prevalence of chronic hepatitis B remains incompletely quantified, with estimates ranging from approximately 800,000 individuals to as high as 2.2 million when including foreign-born Americans. (1,2) Chronic HBV infection is a significant cause of morbidity and mortality, leading to liver failure, cirrhosis, and hepatocellular carcinoma (HCC) in 25%-40% of infected persons. (3) Specifically, in the United States, hepatitis B is the underlying cause of an estimated 1800-4000 deaths each year.…”

“…In contrast to the predominantly Asian-born individuals infected by vertical transmission included in most prior US studies, the majority of Veterans Administration (VA) patients are US-born individuals infected by horizontal transmission, thus representing a unique and understudied population. (1,8,9) The study objectives were to evaluate the delivery of care among US veterans with chronic HBV infection and examine the prevalence and risk factors for adverse clinical outcomes. We also examined potential changes in care patterns after the publication of the 2009 HBV management guidelines released by the American Association for the Study of Liver Diseases (AASLD).…”

Epidemiology of hepatocellular carcinoma in areas of low hepatitis B and hepatitis C endemicity

“…Data from WHO indicate that there are an estimated 2 billion people who have been infected with HBV worldwide, among whom 350 million have chronic HBV infection (Lavanchy, 2004) (Table 3). There is marked geographic variability in the HBV prevalence, with the chronic infection involving fewer than 2 percent of the populations of North America and western and northern European countries; between 2 and 7 percent of peoples in the southern parts of eastern and central Europe, the Amazon basin, the Middle East, and the Indian subcontinent; and greater than 8 percent of persons in Asia, sub-Saharan Africa and the Pacific.…”