Diseases that spread easily have always been around. Sometimes these diseases spread from one person to another person. Sometimes they spread from animals to people. Other times, they spread through germs in the water, soil, food, or air. Some diseases can be prevented or controlled with a vaccination, like measles. Other diseases may not have a vaccine or drugs to treat them. Because of this, it is important to prevent the spread of diseases. Last Reviewed Date: 2020-03-18