Those are caused by a viral infection.

由病毒引起。

So about three billion years ago, bacteria evolved a defense mechanism to fight viral infection.

所以大约30亿年前，细菌进化出一种防御机制来对抗病毒感染。

And pneumonia, often triggered by bacterial or viral infections, attacks the alveoli themselves.

肺炎——常常由细菌或病毒感染引发——会攻击肺泡本身。

Fever and muscle aches are common symptoms for a viral infection.

发烧和肌肉疼痛是病毒感染的常见症状。

The veterinarian said a viral infection caused the marmot's abnormal behavior.

兽医说，病毒感染导致了土拨鼠的异常行为。

Broadly speaking, the genes less active in the lonely were those involved in staving off viral infections.

一般来说，孤独的人体内活力较低的基因是那些帮助人们避开病毒感染的基因。

It's now semi-paralyzed, possibly due to a viral infection the wasp gave it.

瓢虫处于半麻痹状态，可能源自黄蜂造成的病毒感染。

It can be caused by a viral infection or just from yelling too much.

这可能是由病毒感染引起的，或者只是因为大喊大叫得太多了。

And die a slow, agonizing death From a viral infection than work with you.

抑或是染上病毒痛苦而挣扎着死掉也不要和你一起工作。

When the cause is identified, it's usually a viral infection, like Coxsackie B virus.

急性心包炎的已知病因通常是病毒感染，如柯萨奇B组病毒。