David Stern, a medical doctor and believer wrote a book called “None Of These Diseases” based on the promise of God in Ex. 15:26 “If you will give earnest heed to the voice of the LORD your God, and do what is right in His sight, and give ear to His commandments, and keep all His statutes, I will put none of the diseases on you which I have put on the Egyptians; for I, the LORD, am your healer.” The following is from his book:
Leprosy cast the greatest blight that threw its shadow over the daily life of medieval humanity. Fear of all other diseases taken together can hardly be compared to the terror spread by leprosy. Not even Black Death in the fourteenth century or the appearance of syphilis towards the end of the fifteenth century produced a similar state of fright...Early in the Middle Ages, during the sixth and seventh centuries, it began to spread more widely in Europe and became a serious social and health problem. It was endemic particularly among the poor and reached a terrifying peak in the thirteenth and fourteenth century.
Leadership was taken by the church, as physicians had nothing to offer. The church took as its guiding principle the concept of contagion as embodied in the Old Testament...This idea and its practical consequences are defined with great clarity in the book of Leviticus...Once the condition of leprosy had been established, the patient was to be segregated from the community.
Following the precepts laid down in Leviticus the church undertook the task of combating leprosy...it accomplished the first great feat...in the methodical eradication of disease.