chapter 4

Diseases can be communicable or non-communicable as well as chronic or acute. Non-communicable diseases are amongst the leading causes of death in the U.S. but they are not contagious and may be caused by things such as genetics, environmental factors or lifestyle choices rather than pathogens. Communicable diseases are caused by pathogens and can be spread from person to person through either direct or indirect transmission. An epidemiologist's goal of disease prevention and control exists on three levels. During the primary stage, the focus is on immunization, health education, and promoting good health in general. This stage can be considered the pre-disease stage. In the secondary stage, a disease has been identified and the focus has shifted from prevention to controlling the spread of that disease. Preventative measures at the secondary level may not only include public health education, but may also involve things such as isolation and quarantine. By the time the disease reaches the tertiary level of prevention, the focus has become applying both the primary and secondary measures as well as preventing a relapse of the disease. This could in a sense be the recovery phase of the disease because people are recovering and life is returning to normal.When studying the health of a population, an epidemiologist would be concerned with the various rates of natality, morbidity and mortality. While many of those rates have a margin of error, an epidemiologist can use them to follow the course of a disease through a population or to determine the impact of certain lifestyle choices such as smoking or tanning beds on the health of a population. The results of those studies can be used to make recommendations about the prevention and control of diseases, but people are still choosing to engage in behaviors that put themselves at risk.