The Concept of Epidemiology and Its Importance Essay Example

in a population, but happens only when the right accumulation of risk factors or determinants exists in an individual. To search for these determinants, epidemiologists use analytic epidemiology or epidemiologic studies to provide the “Why” and “How” of such events. They assess whether groups with different rates of disease differ in their demographic characteristics, genetic or immunologic make-up, behaviors, environmental exposures, or other so-called potential risk factors. Ideally, the findings provide sufficient evidence to direct prompt and effective public health control and prevention measures. Health-related states or events

Epidemiology was originally focused exclusively on epidemics of communicable diseases3 but was subsequently expanded to address endemic communicable diseases and non-communicable infectious diseases. By the middle of the 20th Century, additional epidemiologic methods had been developed and applied to chronic diseases, injuries, birth defects, maternal-child health, occupational health, and environmental health. Then epidemiologists began to look at behaviors related to health and well-being, such as amount of exercise and seat belt use. Now, with the recent explosion in molecular methods, Introduction to Epidemiology – Epi 592J Page 3 epidemiologists can make important strides in examining genetic markers of disease risk.

Indeed, the term health related states or events may be seen as anything that affects the well-being of a population. Nonetheless, many epidemiologists still use the term “disease” as shorthand for the wide range of healthrelated states and events that are studied. Specified populations Although epidemiologists and direct health-care providers (clinicians) are both concerned with occurrence and control of disease, they differ greatly in how they view “the patient. ” The clinician is concerned about the health of an individual; the epidemiologist is concerned about

the collective health of the people in a community or population. In other words, the clinician’s “patient” is the individual; the epidemiologist’s “patient” is the community.

Therefore, the clinician and the epidemiologist have different responsibilities when faced with a person with illness. For example, when a patient with diarrheal disease presents, both are interested in establishing the correct diagnosis. However, while the clinician usually focuses on treating and caring for the individual, the epidemiologist focuses on identifying the exposure or source that caused the illness; the number of other persons who may have been similarly exposed; the potential for further spread in the community; and interventions to prevent additional cases or recurrences. Application Epidemiology is not just “the study of” health in a population; it also involves applying the knowledge gained by the studies to community-based practice.

Like the practice of medicine, the practice of epidemiology is both a science and an art. To make the proper diagnosis and prescribe appropriate treatment for a patient, the clinician combines medical (scientific) knowledge with experience, clinical judgment, and understanding of the patient. Similarly, the epidemiologist uses the scientific methods of descriptive and analytic epidemiology as well as experience, epidemiologic judgment, and understanding of local conditions in “diagnosing” the health of a community and proposing appropriate, practical, and acceptable public health interventions to control and prevent disease in the community. Summary

Epidemiology is the study (scientific, systematic, data-driven) of the distribution (frequency, pattern) and determinants (causes, risk factors) of health-related states and events (not just diseases) in specified populations (patient is community, individuals viewed collectively), and the application of (since epidemiology is a discipline within

public health) this study to the control of health problems. Evolution Although epidemiologic thinking has been traced from Hippocrates (circa 400 B. C. ) through Graunt (1662), Farr, Snow (both mid-1800’s), and others, the discipline did not blossom until the end of the Second World War. The contributions of some of these early and more recent thinkers are described next. Hippocrates (circa 400 B. C. ) attempted to explain disease occurrence from a rational instead of a supernatural viewpoint. In his essay entitled “On Airs, Waters, and Places,” Hippocrates suggested that environmental and host factors such as behaviors might influence the development of disease.

Another early contributor to epidemiology was John Graunt, a London haberdasher who published his landmark analysis of mortality data in 1662. He was the first to quantify patterns of birth, death, and disease occurrence, noting male-female disparities, high infant mortality, urban-rural differences, and seasonal variations. No one built upon Graunt’s work until the mid-1800, when William Farr began to systematically collect and analyze Britain’s mortality statistics.

Farr, considered the father of modern vital statistics and disease surveillance, developed many of the basic practices used today in vital statistics and disease classification. He extended the epidemiologic analysis of morbidity and mortality data. I he effects of marital status, occupation, and altitude. He also developed many epidemiologic concepts and techniques still in use today. Meanwhile, an anesthesiologist named John Snow was conducting a series of investigations in London that later earned him the title “the father of epidemiology.

Twenty years before the development of the microscope, Snow conducted studies of cholera outbreaks both to discover the cause of the disease

and to prevent its recurrence. Because his work classically illustrates the sequence from descriptive epidemiology to hypothesis generation to hypothesis testing (analytic epidemiology) to application, we will consider two of his efforts.

It is important to mention that at the time of John Snow’s investigations the most widely accepted cause of diseases, including cholera, was due to miasma, or foul air. Therefore most believed that cholera was transmitted by air, especially foul-smelling air near water. The germ theory, that disease was transmitted by microbes, did not gain acceptance until later in the 1800s. Snow conducted his classic study in 1854 when an epidemic of cholera developed in the Golden Square of London. He began his investigation by determining where in this area persons with cholera lived and worked. He then used this information to map the distribution of cases on what epidemiologists call a spot map.

Because Snow believed that water was a source of infection for cholera, he marked the location of water pumps on his spot map, and then looked for a relationship between the distribution of cholera case households and the location of pumps. He noticed that more case households clustered around certain pumps, especially the Broad Street pump, and he concluded that the Broad Street pump was the most likely source of infection. Questioning residents who lived near the other pumps, he found that they avoided certain pumps because the water they provided was grossly contaminated, and that other pumps were located too inconveniently for most residents of the Golden Square area.

From this information, it appeared to Snow that the Broad Street pump was probably the primary

source of water for most persons with cholera in the Golden Square area. He realized, however, that it was too soon to draw that conclusion because the map showed no cholera cases in a two-block area to the east of the Broad Street pump.

Perhaps no one lived in that area, or perhaps the residents were somehow protected. Upon investigating, Snow found that a brewery was located there and that it had a deep well on the premises where brewery workers, who also lived in the area, got their water. In addition, the brewery allotted workers a daily quota of malt liquor. Access to these uncontaminated rations could explain why none of the brewery’s employees contracted cholera.

To provide further evidence that the Broad Street pump was the source of the epidemic, Snow gathered information on where persons with cholera had obtained their water. Consumption of water from the Broad Street pump was the one common factor among the cholera patients. According to legend, Snow removed the handle of the Broad Street pump and aborted the outbreak.