The dog has fleas.

这条狗有跳蚤。

You have rats, snakes, mice and fleas.

你有大老鼠、蛇、鼠和跳蚤。

They infested half the nests with 60 hen fleas each.

他们往一半巢穴各放入60只鸡蚤。

He said when an elephant has fleas, it is the fleas that do the jumping.

他说，当一头大象有了跳蚤，是跳蚤在跳。

Take bubonic plague for example. The disease is most commonly transmitted to humans through flea bites, and the fleas live on rodents.

以黑死病为例。这种疾病最常通过跳蚤叮咬传染给人类，跳蚤生存在啮齿类动物上。