Toby

Hepatitis B is an infectious disease caused by the hepatitis B virus (HBV) which affects the liver. It can cause both acute and chronic infections. Many people have no symptoms during the initial infection. Some develop a rapid onset of sickness with vomiting, yellow skin, feeling tired, dark urine and abdominal pain. Often these symptoms last a few weeks and rarely does the initial infection result in death. It may take 30 to 180 days for 

symptoms to begin. In those who get infected around the time of birth 90% develop chronic hepatitis B while less than 10% of those infected after the age of five do. Most of those with chronic disease have no symptoms; however,cirrhosis and liver cancer may eventually develop. These complications results in the death of 15 to 25% of those with chronic disease.

乙肝（学名：Hepatitis B）是一种传染病，由乙肝病毒（学名：HBV）引起。乙肝病毒感染肝器官，它能引起急性或慢性感染。许多人在感染初期没有症状，另一些人却出现呕吐，皮肤发黄，疲倦乏力，尿黑，腹部疼痛等症状。这些症状一般持续几周，且早期感染很少导致死亡。乙肝病毒感染30-80天后才会出现症状。如果出生时感染乙肝病毒，90%概率会发展为慢性乙肝；如果5岁后感染乙肝病毒，只有不到10%概率发展为慢性乙肝。大多数慢性乙肝患者没有症状，但最终可能导致肝硬化和肝癌。慢性乙肝的并发症导致15%-25%的患者死亡。

The virus is transmitted by exposure to infectious blood or body fluids. Infection around the time of birth or from contact with other people's blood during childhood is the most frequent method by which hepatitis B is acquired in areas where the disease is common. In areas where the disease is rare, intravenous drug use and sexual intercourse are the most frequent routes of infection. Other risk factors include working in healthcare, blood transfusions, dialysis, living with an infected person, travel in countries where the infection rate is high, and living in an institution.Tattooing and acupuncture led to a significant number of cases in the 1980s; however, this has become less common with improved sterility. The hepatitis B viruses cannot be spread by holding hands, sharing eating utensils, kissing, hugging, coughing, sneezing, or breastfeeding.The infection can 

be diagnosed 30 to 60 days after exposure. Diagnosis is typically by testing the blood for parts of the virus and for antibodies against the virus.It is one of five known hepatitis viruses: A, B, C, D, and E.

病毒通过血液和体液传播。在乙肝病毒高发区，出生婴儿或接触他人血液的小孩最容易受到感染。在乙肝病毒较少地区，药品注射和性行为是传播主要途径。其它风险因素包括：在卫生机构工作，输血，透析，与患者同居，前往乙肝高发区旅游。在1980年，纹身和针灸导致了较多乙肝病毒感染，消毒卫生改善后，感染概率会降低。握手，共用餐具，接吻，拥抱，咳嗽，喷嚏和母乳均不会传播乙肝病毒。感染乙肝30-60天后才能被检测。检测包括血液和抗体测试。肝病毒有五种： A, B, C, D, 和 E型，乙肝病毒是其中一种。

The infection has been preventable by vaccination since 1982. Vaccination is recommended by the World Health Organization in the first day of life if possible. Two or three more doses are required at a later time for full effect. This vaccine works about 95% of the time. About 180 countries gave the vaccine as part of national programs as of 2006. It is also recommended that all blood be tested for hepatitis B before transfusion and condoms be used to prevent infection. During an initial infection, care is based on the symptoms that a person has. In those who develop chronic disease antiviral medication such as tenofovir or interferon maybe useful, however these drugs are expensive. Liver transplantation is sometimes used for cirrhosis.

1982诞生的疫苗有效预防乙肝病毒感染。世界卫生组织建议：如果条件允许，婴儿出生的第一天就应该注射乙肝疫苗，稍后应注射第二针和第三针补充剂。疫苗成功概率为95%。2006年，约180个国家把乙肝疫苗作为国家政策。为预防感染，输血前进行乙肝病毒的血检十分必要。早期感染中，根据症状照看患者。慢性乙肝患者可服用抗病毒药，例如替诺福韦；也可使用干扰素。这些药物价格十分昂贵。肝硬化患者可采用肝移植手术。

About a third of the world population has been infected at one point in their lives, including 240 million to 350 million who have chronic infections. Over 750,000 people die of hepatitis B each year. About 300,000 of these are due to liver cancer.The disease is now only common in East Asia and sub-Saharan Africa where between 5 and 10% of adults have chronic disease. Rates in Europe and North America are less than 1%. It was originally 

known as serum hepatitis. Research is looking to create foods that contain HBV vaccine.The disease may affect other great apes as well.

大约三分之一的总人口曾感染过乙肝病毒，其中2.4-3.5亿人发展为慢性乙肝。每年，乙肝病毒导致75万多人死亡。大约30万人死于肝癌。现在乙肝病毒只流行于东亚和撒哈拉以南非洲，那里5-10%的成人有慢性乙肝。欧洲和北美的概率不到百分之一。它最初被称为血清肝炎。科研人员尝试制作包含乙肝病毒疫苗的食品。这疾病也会感染大猩猩。