As you mention leprosy it reminds me of something I've been thinking about recently.
God told the nation of Israel that they are his special property and he would basically make them an impressive remarkable nation compared with the surrounding nations. Recall how God gave special wisdom to two craftsmen so that they can build the ark of the covenant and all the special tabernacle utensils and so on? Well I got to thinking: why didn't God also give special scientific knowledge to chosen men in the nation of Israel?
Think about it: In the space of a few years ancient Israel could have had remarkable technological advancements (far beyond what we know today) due to special knowledge given them by God. They could have had a remarkable medical system with a medical cure for leprosy! Instead, God keeps them in backward scientific ignorance tells them to shun lepers as outcasts!
And just think: the remarkable out-of-this world technological superiority of the nation of Israel would have served as convincing proof of them having a super-intelligent being backing them. Relics of their technological superiority would still be around today to provide a measure of evidence of divine backing . . . but no. God keeps them in basically the same level of technological ignorance as everyone else . . .