Once the source of the outbreak has been identified, it may be necessary to initiate specific control measures in order to contain the epidemic. Military epidemiologists have come up with some novel ideas to control epidemics. For example, in the midst of a diarrheal outbreak at a military base, it helps to post a sentry at the entrance to the mess hall, and prohibit entry to any soldier who does not first wash his hands with soap and water. This is a simple, safe, inexpensive, and fully enforcable method of containment, which has probably been utilized by many of us at one time or another