Hepatitis B

Document presentation of content: Epidemiology and transmission of hepatitis B, pathogenesis and natural history, laboratory diagnosis of hepatitis B, long-term monitoring and screening of chronic hepatitis B, treatment for chronic hepatitis B, hepatitis B vaccination, automatic searches, guidelines, further reading, and web sites.
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Hepatitis B World Gastroenterology Organisation Practice Guideline Hepatitis B September 2008 Review team J. Heathcote (Chair, Canada), Z. Abbas (Pakistan), A. Alberti (Italy), Y. Benhamou (France), C. Chen (Taiwan), A. Elewaut (Belgium), P. Ferenci (Austria), C. Hui (Hong Kong), V. Isakov (Russia), H. Janssen (The Netherlands), G. Lau (Hong Kong), S. Lim (Singapore), T. Okanoue (Japan), S. Ono-Nita (Brazil), T. Piratvisuth (Thailand), M. Rizzetto (Italy), I. Sollano (Phillippines), W. Spearman (South Africa), C-T. Yeh (Taiwan), M. Yuen (Hong Kong), J. Krabshuis (France)Contents 1 Introduction 2 Epidemiology and transmission of hepatitis B 3 Pathogenesis and natural history 4 Laboratory diagnosis of hepatitis B 5 Long-term monitoring and screening of chronic hepatitis B 6 Treatment for chronic hepatitis B 7 Hepatitis B vaccination 8 Automatic searches, guidelines, further reading, and web sites 9 Queries and feedback WGO Practice Guideline Hepatitis B 21 IntroductionHepatitis B is a viral disease process caused by the hepatitis B virus (HBV). The virusis endemic throughout the world. It is shed in all body fluids by individuals with acuteor chronic infection. When transmission occurs vertically (from mother to child) orhorizontally between small children during play, the infection nearly always becomeschronic. By contrast, when transmission occurs in adolescents/adults—usually viasexual contact, contaminated needles (“sharps”), and less often from transfusion ofblood products—the infection usually resolves unless the individual isimmunocompromised (e.g., infected with human immunodeficiency virus). Providingeducation about how to avoid risky behavior can play an important role in prevention. Health-care workers are an at-risk group because of the risk of needlestick injury,and they should therefore all be vaccinated before starting employment. Individuals chronically infected with HBV are at increased risk of developingcirrhosis, leading to hepatic decompensation and hepatocellular carcinoma (HCC).Although most patients with chronic HBV infection do not develop hepaticcomplications, there is a potential for serious illness to develop during their lifetime,and it is more likely to occur in men. Every individual chronically infected with HBV represents an opportunity forfurther cases to be prevented. It is important to take the time needed to educatepatients and to explain the risks that the infection poses to the patients themselves andto others. Hepatitis B vaccination is highly effective, and universal vaccination at a young ageis desirable. At the very least, vaccination should be offered to all individuals who areat risk. Pregnant women must be screened for hepatitis B before delivery, as thisoffers an opportunity to prevent another generation of chronically infected persons. Guidelines must not be resource-blind. This guideline therefore presents sixcascades to provide resource-sensitive options for the prevention and treatment ofhepatitis B.2 Epidemiology and transmission of hepatitis BTwo billion people worldwide have serologic evidence of past or present HBVinfection, and 350 million are chronically infected and at risk of developing HBV-related liver disease. Some 15–40% of chronically infected patients will developcirrhosis, progressing to liver failure and/or HCC. HBV infection accounts for500,000–1,200,000 deaths each year. The prevalence of HBV varies markedly between different regions of the world(Fig. 1). In the literature, a distinction is usually made between areas of high, medium,and low endemicity; recently, the concept of “very low endemicity” has also beenadded. The prevalence of chronic infection ranges from over 10% of the population inSouth-East Asia, China, the Amazon area, and sub-Saharan Africa to less than 1% inwestern Europe and North America. Overall, approximately 45% of the globalpopulation lives in areas of high endemicity. Globalization processes mean that© World Gastroenterology Organisation, 2008 WGO Practice Guideline Hepatitis B 3individuals with hepatitis B who are new immigrants into areas where the chronicHBV infection rate is low may easily go unnoticed.Fig. 1 Hepatitis B carrier rates in different regions of the world (courtesy of Dawson AJ,Lancet Inf Dis 2005;5;120–5). The wide range of prevalence figures for chronic HBV infection is largely related todifferences in age at infection. The chance that acute infection will become chronic is70–90% for perinatally acquired (vertical) infection and 20–50% for (horizontal)infections acquired during early childhood (under the age of 5 years). The chance ofdeveloping chronic HBV ranges from 1% to 3% in adult-acquired HBV infections(unless the individual is immunosuppressed). Seven genotypes of hepatitis B virushave been identified, and their geographic distributions have been established(Table 1).Table 1 Hepatitis B virus infection by genotype Genotype Geographic areas Principal Chronic Median age transmission infection (%) of HBe conversion mode Western Europe Sexual, A North America intravenous drug WGO Practice Guideline Hepatitis B 4 Genotype Geograph ...