A型流感病毒H1N1亞型

A型流感病毒H1N1亞型，是A型流感病毒的一種，也是人類最常感染的流感病毒之一。一些H1N1的種類可以在人類間傳播，包括1918年的流感大爆發，另一些可在雀鳥和豬隻間傳播。
這種病毒的遺傳組成存在爭議。根據它的血凝素蛋白和神經氨酸酶的類型，科學家同意這是一種H1N1病毒。它是由人、豬和禽流感的遺傳物質組成，而世界衛生組織認為它主要是由豬流感的基因組成的[1]。
H1N1新型流感（豬流感）原是一種於豬隻中感染的疾病[來源請求]，屬於A型流感病毒。美國疾管局資料顯示，美國以前即曾有人類感染豬流感之病例。目前墨西哥與美國爆發的豬流感疫情，即為H1N1病毒所引起，但目前對此種結合豬流感、人類流感的新病毒的流行病學了解很少[1]。
2009年3至4月，墨西哥爆發H1N1疫潮，導致過百人感染。疫情其後傳播到全世界。2009年4月30日凌晨，世界衛生組織把全球流感大流行警告級別提高到第5級。2009年6月11日，世界衛生組織將全球流感大流行警告級別提升至最高等級第6級[2][3]。

名稱
A型H1N1流感於2009年爆發時，最初世界衛生組織使用了「豬流感」（swine flu）的名稱，當初獲得大部份國家跟隨，除了以色列因為猶太教禁食豬肉而使用「墨西哥流感」。另還有豬源流感[4]、人類豬（型）流感[5] 、墨西哥流感[6]、北美流感[7][8]、H1N1新型流感[9]，以及2009年H1N1流感[6]等各種不一致的稱呼。然而，沒證據顯示墨西哥是疫症源頭，有關做法純粹出於政治、宗教考慮。後來美國豬農抗議「豬流感」名稱使人誤會病毒經豬隻傳播，要求改稱為「北美流感」，歐盟隨即改稱病毒為「新流感」。
2009年4月30日，由於農業界及聯合國糧農組織的關切，世界衛生組織為免對因豬流感一詞造成流感能經由進食豬肉製品傳播的誤解，當日開始改用A型H1N1流感稱呼該病毒。[10][11][12]。香港初時稱俗稱「豬流感」，其後跟隨改稱「A型H1N1流感」，官方亦開始以「人類豬（型）流感」向外界通報。美國疾控中心則稱之為新型A型H1N1流感(novel Influenza A(H1N1))[13]。 而香港大學微生物學系教授袁國勇表示，世衛將新型流感改名為A型H1N1流感會令人分辨不到新型流感和季節性流感的分別。[14]

病徵
A型流感病毒H1N1亞型的病徵一般與人類季節性流感相似，包括發燒、疲倦、食慾不振和咳嗽。部鈼患者可能流鼻水、喉嚨痛、作嘔、嘔吐及腹瀉。

症狀
A型H1N1流感的患者可能有發高燒（高於攝氏37.8度）、頭痛、全身性肌肉痠痛、關節疼痛、明顯疲勞、咳嗽、喉嚨痛、鼻塞等病徵[29]。25%的患者有腹瀉、嘔吐和像痢疾的癥狀[30]。

病毒傳播途徑
A型H1N1流感病毒可透過飛沫傳染、接觸傳染。
潛伏期:半天到三天，最高可達七天
有效傳染期:發病前一天~發病後第七天
易引發重症對象：20~45歲青壯年人。
治療方式：抗病毒藥物克流感、瑞樂沙，輕症患者可口服潘生丁（雙嘧達莫）並且可能有一定預防作用（注：該方法未經過臨床驗證，僅供相關醫務人員參考）或不必治療即可痊癒。
致死率：墨西哥致死率為6~7%，北美洲則較輕微。
預防方法：與一般流感相同，並避免與豬、鳥禽接觸

2009 Influenza A(H1N1) pandemic

Main article: 2009 flu pandemic

In the 2009 flu pandemic, the virus isolated from patients in the United States was found to be made up of genetic elements from four different flu viruses – North American Mexican influenza, North American avian influenza, human influenza, and swine influenza virus typically found in Asia and Europe – "an unusually mongrelised mix of genetic sequences."[13] This new strain appears to be a result of reassortment of human influenza and swine influenza viruses, in all four different strains of subtype H1N1.
Preliminary genetic characterization found that the hemagglutinin (HA) gene was similar to that of swine flu viruses present in U.S. pigs since 1999, but the neuraminidase (NA) and matrix protein (M) genes resembled versions present in European swine flu isolates. The six genes from American swine flu are themselves mixtures of swine flu, bird flu, and human flu viruses.[14] While viruses with this genetic makeup had not previously been found to be circulating in humans or pigs, there is no formal national surveillance system to determine what viruses are circulating in pigs in the U.S.[15]
On June 11, 2009, the WHO declared an H1N1 pandemic, moving the alert level to phase 6, marking the first global pandemic since 1968.[16]

H1NI Flu Information

With the identification of each new dangerous strain of influenza, scientists have expressed concern that the world is due for a pandemic -- a global outbreak. The U.S. Department of Education is collaborating with health experts and agencies across the federal government to ensure that, in the case of a flu outbreak, critical operations and services will continue. State and local preparedness will be crucial in preventing the spread of the virus. Because schools are centers of community life, we ask that educators and administrators work with local officials to make planning for a flu outbreak a priority. The tools below are designed to assist you in disseminating health information, planning for staff and student absences, and maintaining a learning environment. Show less
With the identification of each new dangerous strain of influenza, scientists have expressed concern that the world is due for a pandemic... Show more


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