What measures for disease prevention that were used historically should be used today? Why do you think some were discarded as preventive measures?
They are asking what you think. However, I hope these sources might help.
http://www.google.com/search?client=safari&rls=en&q=disease+prevention+history&ie=UTF-8&oe=UTF-8
In the future, you can find the information you desire more quickly, if you use appropriate key words to do your own search. Also see http://hanlib.sou.edu/searchtools/.