A crippling disease that reduced people to a state of paralysis. It is traditionally translated into English as "leprosy" because the authors of the Septuagint translated the term into the Greek lepra (λέπρα), or "lepros." However, tzara'at is not a normal, scientifically understood disease, but a form of spiritual discipline. It comes when Israel is wicked and does away when they repent.
See 3 Moses 45:12-17, 4 Moses 47-48, 5 Moses 25:11, Leviticus 13- 14, Deuteronomy 24:8.