What have been some of the strategies implemented to combat these illnesses on the local and national levels?

What are the major causes of disease and death in the 21st century (e.g., chronic illnesses, communicable diseases, etc.) that continue to affect U.S. citizens in spite of the achievements in public health in the past century? What have been some of the strategies implemented to combat these illnesses on the local and national levels? Have they been successful? Include reference citations where appropriate.