Though it had been around for a long time, leprosy became a pandemic in Europe between the 11th and 13th century, leading to the creation of leper ghettos called lazarets or leprosaria (despite not being very contagious). The remains or records of at least 1900 such places were found throughout Europe.

It was believed to be a punishment from God and led to ostracism of the sick. It is still present today and can be fatal if no antibiotics are administered.