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。

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.

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该病的传播纯属当人们极少获得或者不能获得安全饮用水供应时饮用了含有受到寄生虫感染的蚤类的污染水。

It is transmitted exclusively when people who have little or no access to safe-drinking water supply swallow water contaminated with parasite-infected fleas.

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经蚤类叮咬所致的间接传播是染疫啮齿动物与人之间最常见的传播方式。

Indirect transmission through the bite of a flea is the most common route of transmission between plague-infected rodents and humans.

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