In the OT, lepers tore their garments and veiled their faces (13:45) as signs of mourning, and to show that they were separated from public worship and community life. In the NT, Jesus had a special concern for lepers and other social outcasts (Luke 7:22).
Leprosy. The “leprosy” mentioned in the Bible was not what is commonly called leprosy today (Hansen’s disease). Rather, it may have been a form of psoriasis or a fungal infection. Nonetheless it was highly contagious, so those who had leprosy had to follow strict rules of hygiene.
The word unclean occurs more than 130 times in the OT, with half of those occurrences in Leviticus. It is not a statement about a person’s hygiene. Rather, it relates to holiness in worship and in personal conduct (see note on 11:1–47).