醫週譯:Hepatitis A / A型肝炎

Hepatitis A (formerly known as infectious hepatitis) is an acute infectious disease of the liver caused by the hepatitis A virus (HAV).[1] Many cases have little or no symptoms especially in the young.[2] The time between infection and symptoms, in those who develop them, is between two and six weeks.[3] When there are symptoms they typically last eight weeks and may include: nausea, vomiting, diarrhea, yellow skin, fever, and abdominal pain.[2] Around 10–15% of people experience a recurrence of symptoms during the six months after the initial infection.[2] Acute liver failure may rarely occur with this being more common in the elderly.[2]

’’’A型肝炎’’’({{lang-en|hepatitis A}},以前被視為具傳染性的[[肝炎]])是一種發生於[[肝臟]]的[[急性]][[感染|感染疾病]],起因於A型肝炎病毒({{lang|en|hepatitis A virus}}, HAV)<ref name=Sherris>{{cite book | author = Ryan KJ, Ray CG (editors) | title = Sherris Medical Microbiology | edition = 4th | pages = 541–4 | publisher = McGraw Hill | year = 2004 | isbn = 0-8385-8529-9 }}</ref>。在許多案例當中,患者只有少許症狀或無症狀,尤其是年紀較輕的病患<ref name=AFP2012/>。從感染到發病,其潛伏期約為二至六週<ref name="pmid16271543">{{cite journal| author=Connor BA| title=Hepatitis A vaccine in the last-minute traveler| journal=Am. J. Med.| volume=118 |issue=Suppl 10A| pages=58S–62S| year=2005| pmid=16271543| doi=10.1016/j.amjmed.2005.07.018}}</ref>。如果出現症狀,持續時間通常為八週,症狀可能包含:噁心、嘔吐、腹瀉、[[黃疸|皮膚發黃]]、發燒和腹痛。約10至15%的病患,在初次感染後6個月內會出現復發症狀。極少數病患可能出現{{link-en|急性肝功能衰竭|Acute liver failure}},這在老年患者中比較常見<ref name=AFP2012/>。

It is usually spread by eating or drinking food or water contaminated with infected feces.[2] Shellfish which have not been sufficiently cooked is a relatively common source.[4] It may also be spread through close contact with an infectious person.[2] While children often do not have symptoms when infected they are still able to infect others.[2] After a single infection a person is immune for the rest of their life.[5] Diagnosis requires blood testing as the symptoms are similar to those of a number of other diseases.[2]

A型肝炎最常見的傳染途徑,是食入或飲用到被感染者糞便汙染的食物或飲水<ref name=AFP2012>{{cite journal|last=Matheny|first=SC|last2=Kingery |first2=JE|title=Hepatitis A.|journal=Am Fam Physician |date=1 December 2012|volume=86|issue=11|pages=1027–34; quiz 1010–2|pmid=23198670 |url=http://www.aafp.org/afp/2012/1201/p1027.html}}</ref>,有時也可見到因為食用未煮熟的{{link-en|貝類|Shellfish}}而感染的病例<ref>{{Cite journal  | last1 = Bellou | first1 = M. | last2 = Kokkinos | first2 = P. | last3 = Vantarakis | first3 = A. | title = Shellfish-borne viral outbreaks: a systematic review. | journal = Food Environ Virol | volume = 5 | issue = 1 | pages = 13–23 |date=March 2013 | doi = 10.1007/s12560-012-9097-6 | pmid = 23412719 }}</ref>,與患者有密切接觸也可能會因此感染。兒童感染A型肝炎時經常沒有症狀,但他們仍然具有傳染力<ref name=AFP2012/>。在感染過A型肝炎後,患者終身對A型肝炎免疫<ref>{{cite book|title=The Encyclopedia of Hepatitis and Other Liver Diseases|year=2006|publisher=Infobase |isbn=9780816069903|page=105|url=http://books.google.ca/books?id=HfPU99jIfboC&pg=PA105}}</ref>。由於A型肝炎的狀況與許多疾病類似,需要血液檢驗才能確診<ref name=AFP2012/>。

The hepatitis A vaccine is effective for prevention.[2][6] Some countries recommend it routinely for children and those at higher risk who have not previously been vaccinated.[2][7] It appears to be effective for life.[2] Other preventative measures include hand washing and properly cooking food.[2] There is no specific treatment, with rest and medications for nausea or diarrhea recommended on an as needed basis.[2] Infections usually resolve completely and without ongoing liver disease.[2] Treatment of acute liver failure, if it occurs, is with liver transplantion.[2]

{{link-en|A型肝炎疫苗|Hepatitis A vaccine|疫苗}}可以有效地預防A型肝炎<ref name=AFP2012/><ref name=Irv2012>{{Cite journal  | last1 = Irving | first1 = GJ. | last2 = Holden | first2 = J. | last3 = Yang | first3 = R. | last4 = Pope | first4 = D. | title = Hepatitis A immunisation in persons not previously exposed to hepatitis A. | journal = Cochrane Database Syst Rev | volume = 7 | issue =  | pages = CD009051 | year = 2012 | doi = 10.1002/14651858.CD009051.pub2 | pmid = 22786522 }}</ref>,完成疫苗施打後的效力多可達終生<ref name=AFP2012/>,部分國家建議對兒童與高危險群進行全面接種疫苗<ref name=AFP2012/><ref name=WHO2013/>。其他預防方法包括{{link-en|洗手|Hand washing}}與正確的食物處理方式。A型肝炎並沒有特定的治療方式,一般建議患者多休息,如果有[[噁心]]或[[腹瀉]]可以考慮給予症狀治療藥物。A型肝炎多能完全痊癒而不會變成慢性肝病,但當A型肝炎造成急性肝衰竭,則有時需{{link-en|肝臟移植|liver transplantion}}<ref name=AFP2012/>。

Globally around 1.5 million symptomatic cases occur each year[2] with likely tens of millions of infections in all.[8] It is more common in regions of the world with poor sanitation and not enough safe water.[7] In the developing world about 90% of children have been infected by age 10 and thus are immune by adulthood.[7] It often occurs in outbreaks in moderately developed countries where children are not exposed when young and there is not widespread vaccination.[7] In 2010, acute hepatitis A resulted in 102,000 deaths.[9] World Hepatitis Day occurs each year on July 28 to bring awareness to viral hepatitis.[7]

每年全球有150萬人受到A型肝炎感染發病<ref name=AFP2012/>,若加上沒有症狀的感染者,則可能達數千萬<ref name=Was2006>{{cite journal|last=Wasley|first=A|author2=Fiore, A |author3=Bell, BP |title=Hepatitis A in the era of vaccination.|journal=Epidemiol Rev |year=2006|volume=28|pages=101–11|pmid=16775039 |doi=10.1093/epirev/mxj012 |url=http://epirev.oxfordjournals.org/content/28/1/101.long}}</ref>,而2010年時造成102,000人死亡<ref name=Loz2012>{{cite journal|last=Lozano|first=R|title=Global and regional mortality from 235 causes of death for 20 age groups in 1990 and 2010: a systematic analysis for the Global Burden of Disease Study 2010|journal=Lancet|date=Dec 15, 2012|volume=380|issue=9859|pages=2095–128|pmid=23245604|doi=10.1016/S0140-6736(12)61728-0|first2=M|first3=K|first4=S|first5=K|first6=V|first7=J|first8=T|first9=R|first10=SY|first11=M|first12=HR|first13=LM|first14=KG|first15=C|first16=LM|first17=S|first18=DH|first19=ML|first20=EJ|first21=D|first22=K|first23=B|first24=A|first25=G|first26=F|first27=I|first28=S|first29=C|first30=M}}</ref>。A型肝炎感染多發生於衛生環境不佳,而且欠缺安全的飲水來源的地區。在[[開發中國家]],約90%的孩子在十歲前就已感染A型肝炎,因此成年時多已免疫。因為上述的現象,A型肝炎流行的爆發多在中度開發國家,好發於未感染過A型肝炎且又未接受疫苗接種的年輕一代。為增進大眾對{{link-en|病毒性肝炎|Viral hepatitis}}的認識,每年的7月28日被訂為[[世界肝炎日]] <ref name=WHO2013>{{cite web|title=Hepatitis A Fact sheet N°328|url=http://www.who.int/mediacentre/factsheets/fs328/en/|work=World Health Organization|accessdate=20 February 2014|date=July 2013}}</ref>。