甲型肝炎

title: 病原体.
content: 甲型肝炎病毒是一种没有外壳的、单链的核糖核酸病毒,它属于微小核糖核酸病毒科肝病毒属("Hepatovirus")。它是在世界上造成急性肝炎的最重要的病原体。在卫生条件好的国家里很少能够接触到这种病毒。这种病毒抗高温、酸碱的能力非常高。它一般通过接触或食物和水的途径传染。因此在公共卫生和家庭卫生差的地区感染率相当高。
title: 分布.
content: 甲型肝炎在东南亚、俄罗斯、中国、中东、地中海地区、整个非洲和中美洲以及南美洲非常常见。
title: 传播.
content: 甲型肝炎通过消化道传播,比如通过手触摸到粪便或者尿,然后触摸口。紧密的身体接触、不干净的饮水和没有足够煮沸的食物、粪便污染的食物是最常见的感染途径。尤其是使用粪便施肥的蔬菜和海产品(比如贝壳等)非常容易感染甲型肝炎。
title: 过程.
content: 甲型肝炎的潜伏期是15至50天,平均约28天。急性甲型肝炎可以维持数周以至数月。与其它病毒性肝炎相比甲型肝炎比较缓和,尤其儿童的病状一般比较轻,有时甚至完全没有病状。甲型肝炎从不转化为慢性,因此不会导致肝脏长期被破坏。甲型肝炎最容易感染的时候是病状爆发前一至两周时。但是在病好一周后病人依然可能感染其他人。虽然大多数病人不必入院,但是约十分之一的病人必须入院治疗。治愈时间一般为四至八周(极少达18个月)。
title: 症状.
content: 潜伏期后病人会恶心、呕吐、腹痛、发热、腹泻、精神萎靡,一般甲型肝炎没有黄疸,少数有严重黄疸,尿颜色深,有可能发生胆汁堵塞。
title: 诊断.
content: 当病人因肝炎症状就医时,几乎为血清IgM Anti-HAV,因此敏感度极高。IgG Anti-HAV出现时间较慢,急性甲肝发病三周后呈阳性,此标记可持续多年,但只能代表曾感染甲肝及有免疫力,无法证明急性或是感染时间。
title: 预防或治疗.
content: 接种甲型肝炎疫苗为预防甲型肝炎病毒感染相当有效的方法之一。一般而言,免疫力约可持续20年。  针对甲型肝炎可以接种疫苗来作为预防或治疗用途。过去疫苗是被动疫苗,近来也有主动疫苗。过去疫苗要分三次注射入肌肉,第二次在第一次后约两周注射,第三次在半年后。一疫苗种类的不同,一般完成二至三次接种后,疫苗的保护力约为6~8年。依照WHO显示;12个月以下的幼儿不可接种甲型肝炎疫苗。

Summary: 在中国大陆常简称甲肝,是一种发生于肝脏的急性感染疾病,起因于甲型肝炎病毒(英语:hepatitis A virus, HAV)。在许多案例当中,患者只有少许症状或无症状,尤其是年纪较轻的病患。从感染到发病,其潜伏期约为二至六周。如果出现症状,持续时间通常为八周,症状可能包含:恶心、呕吐、腹泻、皮肤发黄、发烧和腹痛。约10至15%的病患,在初次感染后6个月内会出现复发症状。严重病患可能出现急性肝功能衰竭,这在老年患者中比较常见。 甲型肝炎最常见的传染途径,是食入或饮用到被感染者粪便污染的食物或饮水,有时也可见到因为食用未煮熟的贝类而感染的病例,与患者有密切接触也可能会因此感染。儿童感染甲型肝炎时经常没有症状,但他们仍然具有传染力。在感染过甲型肝炎后,患者终身对甲型肝炎免疫。由于甲型肝炎的状况与许多疾病类似,需要血液检验才能确诊。 疫苗可以有效地预防甲型肝炎,完成疫苗施打后的效力多可达终生,部分国家建议对儿童与高危险群进行全面接种疫苗。其他预防方法包括洗手与正确的食物处理方式。甲型肝炎并没有特定的治疗方式,一般建议患者多休息,如果有恶心或腹泻可以考虑给予症状治疗药物。甲型肝炎多能完全痊愈而不会变成慢性肝病,但当甲型肝炎造成急性肝衰竭,则有时需肝脏移植。 每年全球有150万人受到甲型肝炎感染发病,若加上没有症状的感染者,则可能达数千万,而2010年时造成102,000人死亡。甲型肝炎感染多发生于卫生环境不佳,而且欠缺安全的饮水来源的地区。在开发中国家,约90%的孩子在十岁前就已感染甲型肝炎,因此成年时多已免疫。因为上述的现象,甲型肝炎流行的爆发多在中度开发国家,好发于未感染过甲型肝炎且又未接受疫苗接种的年轻一代。为增进大众对病毒性肝炎的认识,每年的7月28日被订为世界肝炎日 。

Hepatitis A: Hepatitis A is an infectious disease of the liver caused by "Hepatovirus A" (HAV); it is a type of viral hepatitis. Many cases have few or no symptoms, especially in the young. The time between infection and symptoms, in those who develop them, is between two and six weeks. When symptoms occur, they typically last eight weeks and may include nausea, vomiting, diarrhea, jaundice, fever, and abdominal pain. Around 10–15% of people experience a recurrence of symptoms during the six months after the initial infection. Acute liver failure may rarely occur, with this being more common in the elderly. It is usually spread by eating food or drinking water contaminated with infected feces. Shellfish which have not been sufficiently cooked are a relatively common source. It may also be spread through close contact with an infectious person. While children often do not have symptoms when infected, they are still able to infect others. After a single infection, a person is immune for the rest of his or her life. Diagnosis requires blood testing, as the symptoms are similar to those of a number of other diseases. It is one of five known hepatitis viruses: A, B, C, D, and E. The hepatitis A vaccine is effective for prevention. Some countries recommend it routinely for children and those at higher risk who have not previously been vaccinated. It appears to be effective for life. Other preventive measures include hand washing and properly cooking food. No specific treatment is available, with rest and medications for nausea or diarrhea recommended on an as-needed basis. Infections usually resolve completely and without ongoing liver disease. Treatment of acute liver failure, if it occurs, is with liver transplantation. Globally, around 1.4 million symptomatic cases occur each year and about 114 million infections (symptomatic and asymptomatic). It is more common in regions of the world with poor sanitation and not enough safe water. In the developing world, about 90% of children have been infected by age 10, thus are immune by adulthood. It often occurs in outbreaks in moderately developed countries where children are not exposed when young and vaccination is not widespread. Acute hepatitis A resulted in 11,200 deaths in 2015. World Hepatitis Day occurs each year on July 28 to bring awareness to viral hepatitis.