Infectious bronchitis may also be caused by bacteria. Often bacterial bronchitis follows a viral upper respiratory infection.

感染性支气管炎，也是由细菌引起，细菌性支气管炎常伴发病毒性上呼吸道感染。

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Theory Background: Acute viral upper respiratory infection is a most common clinic infective disease, and about 70%-80% of it is caused by virus.

理论背景急性上呼吸道感染是临床最常见的一种感染性疾病，约有70% - 80%由病毒引起。

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Theory Background: the high fever originated from viral upper respiratory infection is one of the most familiar emergency cases in internal medicine; of which 70%-80% is caused by the virus infection.

研究背景：急性上呼吸道感染所引起的发热是内科最常见急症之一，70% - 80%是由病毒感染引起。

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