In general, control measures for stopping an epidemic include: reducing the contact rate, reducing the prevalence of infectious sources, interrupting transmission, and reducing susceptibility. How do these control measures stop an epidemic?
“Reducing the contact rate,” is to reduce the amount of contact people have with one another. This helps to stop an epidemic because when people have contact with others, this presents an opportunity for disease to spread from one person to many others. Reducing the contact rate makes it less likely for the disease to spread, which slows the epidemic. Examples of this control measure would to be close schools and workplaces, educating people to not get too close to those who are sick, and putting the sick in quarantine.
“Reducing the prevalence of infectious sources” means to reduce the number of infected people (or animals), so that there are less sources that could potentially spread disease to the uninfected. This is usually accomplished by finding and treating sick individuals. For diseases such as malaria (which is spread by mosquitoes), this is accomplished spraying chemicals to eliminate mosquitoes, thus eliminating contagious sources.
“Interrupting transmission” means to directly prevent the disease from spreading to other people. This is done by using “barriers” (like masks) or by environmental disinfection.
“Reducing susceptibility” means to make the people who have not caught the disease more likely to not develop the disease once they have been exposed to the agent. If a patient does not develop the disease, they cannot spread the disease to others, thus helping to control the epidemic. This is accomplished by vaccination before, or in some cases, after exposure to the agent.
"Steps of an Outbreak Investigation." Centers for Disease Control and Prevention.
. Aragón, Tomás, Wayne Enanoria, and Arthur Reingold. Essential Field Epidemiology. Center for Infectious Disease Preparedness, UC Berkeley School of Public Health. 2006.