Charles Ellicott Commentary Leviticus 13:46

"All the days wherein the plague is in him he shall be unclean; he is unclean: he shall dwell alone; without the camp shall his dwelling be." — Leviticus 13:46 (ASV)

He shall dwell alone. —In consequence of his extreme defilement, the leper had to live in seclusion outside the camp or city (Numbers 5:1–4; Numbers 13:10–15; 2 Kings 7:3, and other passages). According to the legislation during the Second Temple period, if he stood under a tree and a clean person happened to pass by, he defiled the passerby.

In the synagogue he wished to attend, they were required to make a separate compartment for him, ten handbreadths high and four cubits long and broad. He had to be the first to go in and the last to leave the synagogue. Hence, leprosy was regarded as a living death and as an awful punishment from the Lord (2 Kings 5:7; 2 Chronicles 26:20), which they invoked upon all their mortal enemies (2 Samuel 3:29; 2 Kings 5:27). The leper was debarred from conjugal intercourse.

These ancient Rabbinic laws were imported into the Christian Church during the Middle Ages. When anyone was afflicted with this disease, the priest, wearing his stole and holding the crucifix, would conduct him into the church. There, the leper had to exchange his clothes for a distinctive black garment, and the mass was read over him, and the service for the dead was performed.

He was then taken to a secluded house, where earth was thrown upon his feet as a sign of burial. He was also admonished to appear only in his black garment and barefoot. He was not allowed to enter a church, or any place where a mill operated or bread was baked, or to come near a well or fountain. Furthermore, he forfeited both the right of inheritance and of disposing of his property, because he was considered a dead man.