During the Middle Ages, sick people wore a bell or a rattle with them. Which disease did they have?

Leprosy was incurable, but people could live for long with the disease (unlike the cases of other epidemics). Since leprosy was found infectious, leprosy stigma has been universal, and has been present in all parts of the world where leprosy was present. In Europe, the leper would carry a clapper and bell to warn of his approach.