The plague had many causes: a lack of education, poor sanitary conditions, and a

failure to deal with the problem in a timely manner. 

       Common men did not realize that fleas infected black rats, which in turn bit humans. The

fleas traveled in the caravans people used to go from east to west.  Many Europeans did not

take much notice of a rat bite.  They lived in dangerous and unsanitary conditions, and another

bite meant very little.  They attempted to stop the disease by praying to God.  In order to pray,

people packed into their churches and outside on the streets.   The rats thrived in those very

places where the people gathered, and large numbers of people became infected.  Thus, the

disease spread quickly.  Europeans, unaware of what caused the disease, were puzzled over

the “outbreak” of the plague.  

       Approximately one-third to two-thirds of the population (mostly common people) died from

the Black Death.  Instead of rationally dealing with the sanitary problems that led to higher

populations of rats, people did irrational things.  Families would not care for the victims and ran

away from infected family members, so as not to catch the disease.  This allowed the disease to

continue to spread, until it became what was known as The Black Death.