Prevention of disease is divided into 3 levels. Primary prevention is aimed at maintaining a healthy population. Preventing the occurrence of disease. Secondary prevention (also called disease control) attempts to minimize resultant damage after disease has occurred and primary prevention has failed. Tertiary prevention consists of rehabilitation after primary and secondary prevention have failed. There are simple things you can do to prevent illness such as wash your hands often, be aware of what you eat, use antibiotics exactly as prescribed, avoid areas of insect infestation, and when sick allow yourself time to heal and recover.