Answer:
regular childhood vaccination
good sanitation
availability of medical care and treatment
Step-by-step explanation:
The United States controls and prevents the spread of diseases in many ways. One of which is "regular childhood vaccination." This is considered to be the most effective way. There are about 10 vaccines that are recommended to kids.
The USA also follows good sanitation which includes potable drinking water supply available to most people and having enough sewers were wastes are expelled.
Medical care and treatment in the USA is more advanced than other countries. This is the reason why some people seek treatment in the USA when their disease is also more advanced and debilitating. The USA has specialized facilities catering to different kinds of diseases and their corresponding treatments.