Leprosy- Recorded as early as 600 BC in India and appearing in Europe sometime before 1000, leprosy is a disease caused by the leprosy bacillus, a type of bacteria. Of course the bacillus was not discovered until the 19th century, and during the middle ages, sufferers were thought to be "unclean" and excluded from towns and medieval life in general. The disfigurement caused by leprosy was actually caused by nerve and circulation damage to the limbs and extremities. The nerves in the hands and feet (as well as noses, ears etc) would become damaged, causing these parts to become numb and difficult to move. This in turn would lead to these parts of the body becoming damaged and infected.

Smallpox- Also called "pox" or "the pox", evidince of smallpox goes back to 10,000 BC; even some egyptian mummies have been found to have smallpox scars! The first recorded smallpox in eastern europe was described by a Persian physician in the 10th century. Smallpox was a disease characterized by sores, especially on the face. It's well known that smallpox decimated native american populations when europeans came to settle, and it's probably safe to assume that when smallpox first reached europe it was just as devestating. There was one recorded plague of smallpox in 1693-1694 in England; the young Queen Mary was one of it's victims.