On several occasions in the New Testament, we see Jesus healing lepers. Most people know that lepers were quarantined away from other people and that this was really difficult for them to bear.
Leviticus 13 is where we find instructions to priests on how to deal with people with leprosy. The Israelites were in the wilderness when they received these counsels from God through Moses. The instructions begin by telling the people to be on the lookout for “swelling, a scab, or a bright spot.” If one of these situations starts to look like it’s a leprous sore, then Aaron or one of his sons needs to be consulted.
If the hair on the sore had turned white, and the sore appeared to be deeper than the skin of the person’s body, then it was considered a leprous sore. Then the priest was commanded to examine the person and pronounce him or her unclean. An unclean person had to withdraw from others completely.
If these symptoms were not there, then the priest would separate the person from the congregation for 7 days. After the 7 days, the priest would examine the sore again. If the sore was not worse, then the priest sent the person away for another 7 days. After that time, the sore should be healing. If it really was getting better, the person was told to wash his clothes and was declared clean.
If at any time the scab spread, the person would be declared to have leprosy and would be declared unclean. Leviticus then goes on with a list of possible symptoms for the person with the sore. Has it spread all over the body? Is it a sore broken through a boil? Are there white hairs? Was the person burned? Is there a bright spot? Are there scales or yellow hairs in a woman’s hair or a man’s beard? Is the person bald with a reddish-white sore?
Leviticus 13 then goes on about various fabrics that might have been contaminated by a person’s sores. Sometimes the blanket or piece of clothing can be washed and set aside for a while, but other times it had to be burned.
These instructions were far more advanced than the science of the time, and they continued to be up through the Middle Ages. In Europe during the Middle Ages, the plague killed millions of people. By following Law of Moses’ instructions (including quarantining yourself if you were with someone sick, dying, or dead), the Jews didn’t get sick like other people did. This backfired because some people blamed the plague on the Jews.