There are three types of seasonal influenza – A, B and C. Type A influenza viruses are further typed into subtypes according to different kinds and combinations of virus surface proteins.

有三种类型的季节性流感——甲型、乙型和丙型。 根据病毒表面蛋白不同的种类和结合情况，甲型流感病毒又进一步分类为亚型。

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Swine influenza (swine flu) is an acute viral infection of the respiratory tract in pigs caused by type A influenza virus.

猪流感是一种发生在猪身上的高度传染性急性呼吸道疾病，由A型流感病毒引起。

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Avian influenza virus type a has been identified as the cause, but the virus strain has not yet been determined.

禽流感A型病毒已被确认为病因，但是尚未确定病毒株。

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Swine flu is a respiratory disease which is caused by a strain of the influenza type A virus known as H1N1.

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It is caused by a type-A influenza virus.

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