She didn't understand how she could give people typhoid fever when she herself did not appear to have the disease.

她不明白当她自己似乎没有伤寒时，她怎么能把伤寒传染给别人。

The final part of our mystery – how it was possible for Mary to give others typhoid fever without herself getting sick from the disease – was not solved until many years later.

我们谜团的最后一部分 - 玛丽如何可能给别人伤寒而不生病 - 直到多年后才被解决。