question_answer

How did hygienic environment that was created in the French city become the cause of plague?

Answer:

                The large sewers in the modern part of the city, a symbol of modernity, were an ideal and protected breeding ground for rats. The sewers also served as a great transport system, allowing the rats to move around the city without any problem. And rats began to enter the well-cared-for homes of the French though the sewage pipes.