Solution :
It was commonly believed that the cause of the some of the deadly disease like cholera, fever, etc. are caused due to a theory called the miasma theory. People in the period c1250 to c1500 believed that many such diseases caused due to some noxious form of a bad air. This 'bad air' is also known as the night air. It was the polluted air and people believed it the main cause of some deadly disease.
This believed also continued through the period c1500 to c1700. This was mainly due to the dominance and influence of the church at that time.
Th treatment at both the period includes some natural treatment as well as some believes in supernatural treatment.
Some of the treatments includes caused bleedings, or vomiting. People also pray to God and cry to earn God's forgiveness.