Leviticus 11 spells out the unclean animals. There are justifications given, like because the animal has a cloven hoof or whatever, that I find interesting because they remain arbitrary–which most acts of obedience are. It is not at all clear to me that these laws are about health or food safety as has been suggested, possibly by me, elsewhere.
Leviticus 12 spells out the ritual for a woman made unclean by childbirth. Note, she is necessarily unclear. Becoming unclear and being restored seems a necessity.
Leviticus 13 tells you
what offerings to make when you are cured of illnesses including Leprosy. So, people are cured of Leprosy frequently enough that you need a ritual for it? I am not sure what this means, but it seems worth pausing for. Okay, so I was a little rushed when I was writing this, and a little overconfident in my Spanish. A reading in English reveals chapter 13 just tells you want is clean an unclean and reads like a medical journal about puss. [Update 2/17/17]