why bird flu can kill people? 40分

why bird flu can kill people?

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要50字,5要多過50字

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  • 1 decade ago
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    Avian flu (also bird flu, avian influenza, bird influenza), means flu from viruses adapted to birds, but is sometimes mistakenly used to refer to both other flu subsets and the viruses that cause them. (Example: from any flu virus rather than ones adapted to birds, e.g. Dog flu, Horse flu, Human flu, Swine flu), or (also incorrectly) even the virus itself.

    All known avian flu viruses belong to the species of virus called Influenza A virus. All subtypes (but not all strains of all subtypes) of Influenza A virus are adapted to birds, which is why for many purposes avian flu virus is the Influenza A virus (note that the A does not stand for avian).

    Avian flu viruses are noninfectious for most species. When they are infectious they are usually asymptomatic, so the carrier does not have any disease from it. Thus while infected with an avian flu virus, the animal doesn't have a "flu&qu ot;. Typically, when illness (called "flu&qu ot;) from an avian flu virus does occur, it is the result of an avian flu virus strain adapted to one species spreading to another species (usually from one bird species to another bird species). So far as we know the most common result of this is an illness so minor as to be not worth noticing (and thus little studied). But with the domestication of chickens and turkeys, we have created species subtypes (domesticated poultry) that can catch an avian flu virus adapted to waterfowl and have it rapidly mutate into a form that kills in days over 90% of an entire flock and spread to other flocks and kill 90% of them and can only be stopped by killing every domestic bird in the area. Until H5N1, this was basically the whole story of avian flu so far as anyone knew or cared (outside of the poultry industry). Now with H5N1, we have a whole new ballgame with H5N1 inventing new rules as it goes with behaviors never noticed before, and possibly never having occurred before. This is evolution right before our eyes. Even the Spanish flu virus did not behave like this. What is worth mentioning about illness from avian flu viruses is covered in H5N1 flu, Flu, and the subtype articles (H5N1, HxNy) linked below.

    As of 2006, avian flu is being commonly used to refer to infection from a particular subtype of Influenza A virus, H5N1, which can cause severe illness in humans who are infected.

    Currently, this strain is transmitted by contact with infected birds, and has been transmitted from one person to another only in a few cases.

    H5N1 flu is therefore not pandemic now and is not currently capable of causing a pandemic. Only if H5N1 mutates into a form that can be readily transmitted from one person to another could it cause a pandemic.

    You may also go to the United Nation's World Health Organization' ;s Avian Flu Facts Sheet for 2006 at the website of the UN WHO World Health Organization

  • 1 decade ago

    其實每種病都有佢嘅antibody. 自要人身上有病毒嘅antibody就唔會有個種病如白喉,天花,birdflu暫時未有有效注射疫苗 

  • 1 decade ago

    死亡的原因通常是因為併發症而造成,例如因病毒感染而令支氣管腫脹,呼吸困難而死亡,或因病毒感染了肺部,造成肺炎而死亡等等。

    禽流感

    H5N1禽流感病毒是甲型流感的一種,本來只影響禽類,如雞、鴨等,而香港在1997及2003年分別發現有18宗及2宗人類感染的個案。H5N1禽流感是透過與活家禽近距離接觸而傳播,而人類之間的傳播能力十分之低。最近多個亞洲國家報告雞隻中出現禽流感,主要影響家禽,但人類亦有受感染個案。

    “禽流感”是流行性感冒的一種,主要由甲型H5N1及H9N2流感病毒引起,由於它是由一種來自家禽或鳥類的流感病毒所引起,故此,我們稱這種病為禽流感。所有鳥類均有感染禽流感病毒的可能,而家禽如雞、鴨等,就特別容易染病,更會迅速發展為流行病,貓科動物(貓、虎等)及豬也偶然會受感染。禽流感的病徵一般是發燒,鼻炎,喉嚨發炎,咳嗽,喉嚨痛,嘔吐等,這些與“傷風”,“感冒”的病徵十分相似,但是它們是不同的。

    禽流感病毒是粘液病毒(myxovirus)的一種,病毒的形狀呈球形,直徑約為1x10-9米,與所有病毒的構造相類似,它們有一個蛋白質的外殼,裡面貯存了一些核酸,而禽流感病毒的核酸是核糖核酸(RNA),這些核糖核酸能夠製造出外殼的蛋白質,其中包括外殼的血凝素(hemagglutinin,我們可簡稱它為H),和神經酸酵素(neuraminidase,我們可簡稱它為N)這兩種蛋白質存在外殼之上,醫學界也以不同的H和N來將禽流感病毒分類及加以辨認,例如早陣子,香港流行的是A(H5N1),即是說,該禽流感病毒的外殼有第五型號的血凝素及第一型號的神經酸酵素。

    禽流感和其他流感一樣,傳染的途徑是可因與病人接觸,或吸入浮在空氣中的病毒。當禽流感病毒接觸到人的細胞,它可以穿過細胞膜而進入。

    流感分甲,乙,丙三型,其中以甲型比較普遍,危害也最大。禽流感就是屬於甲型的,潛伏期是一至四天。甲型流感是可以致命的。死亡的原因通常是因為併發症而造成,例如因病毒感染而令支氣管腫脹,呼吸困難而死亡,或因病毒感染了肺部,造成肺炎而死亡等等。

    禽流感所引起的症狀,跟其他流感一樣,發燒,咳嗽,喉嚨痛,流鼻水,全身肌肉酸痛。而且他跟其他感冒,傷風等上呼吸道感染常見的徵狀也相似。更有一些情況,是病毒感染到腸胃去,引起嘔吐、肚痛、肚屙等等。嚴重的,還會透發肺炎(pneumonia)。

    若果有以下的病徵,例如發高熱,呼吸困難,咳嗽不斷,嘔吐,在病發了五、六天後,病情沒有好轉,反而有加深之勢,就事不嫌遲,立即去看醫生。

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