Upvote:7
Improvement in sanitation, based on the understanding that not washing your hands causes disease, is a relatively new concept.
Ignaz Semmelweis was the first man to work out the correlation and publish data. This was in the 1840's, a good couple of centuries after most of the plague had gone from Europe.
It's not just that he was the first to discover it, he had to fight the medical establishment of the day to get his data accepted and understood. Basically, sanitation as a health issue was only accepted in the mainstream near the end of the 19th century.