The city is under threat from a plague of rats.

这座城市面临着鼠患的威胁。

《柯林斯英汉双解大词典》

And bubonic plague, spread by rat fleas, is normally preceded by the death of hordes of rats (only then do the fleas opt for humans). Yet no one in 1348 recorded this.

黑死病由鼠蚤传播，在此之前通常都有大批的老鼠死亡(只有在这时跳蚤才选择人类作宿主)，但在1348年没有人记录下这些。

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With their staple diet of rats and mice in plentiful supply in a season, stoats fed well and their numbers reached plague levels.

如果一个繁殖季节中白鼬有充足的沟鼠和鼷鼠为主食，它们就会生长良好，且数量会达到猖獗的程度。

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The Yersinia pestis bacterium that is behind the plague is found mainly in rodents, particularly rats, and in the fleas that feed on them, the U.S. National Institutes of Health website says.

CNN: London rail excavation unearths suspected 'plague pit'

The Yersinia pestis bacteria that is behind the plague is found mainly in rodents, particularly rats, and in the fleas that feed on them, the U.S. National Institutes of Health website says.

CNN: London rail excavation unearths suspected 'plague pit'

But the problems posed by rats are nothing compared with the mosquito plague.

ECONOMIST: King Rat