Oct 9, Epidemiology is the method used to find the causes of health outcomes and diseases in populations. In epidemiology, the patient is the. Epidemiology is the study of the distribution and determinants of health-related states or events (including disease), and the application of this study to the. Epidemiology is the study of how often diseases occur in different groups of people and why. Epidemiological information is used to plan and evaluate strategies.
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Oxford University Press is a department of the University of Oxford. It furthers the University's objective of excellence in research, scholarship, and education by publishing worldwide. Sign In or Create an Account. Volume Issue 2 February In most instances the epidemiology of infectious disease is characteristic of that disease and is an outgrowth….
Epidemiology emerged as a formal science in the 19th century. However, its historical development spanned centuries, in a process that was slow and unsteady and aided by the contributions of many individuals. One of the first major figures in the historical development of epidemiology was the ancient Greek physician Hippocrates , who is traditionally regarded as the father of medicine.
Hippocrates is presumed to have written the Epidemics and On Airs, Waters, and Places , works in which he attempted to explain the occurrence of disease on a rational rather than supernatural basis.
Hippocrates recognized disease as a mass phenomenon as well as one affecting individuals. Another significant contribution to the foundation of epidemiology was made in the 17th century, with the work of English statistician John Graunt.
Graunt was the first person to analyze the bills of mortality, which recorded the weekly counts of christenings and deaths in London. In Graunt published the results of his findings in Natural and Political Observations Made upon the Bills of Mortality.
He found that although male births consistently outnumbered female births, males no longer outnumbered females by the time they reached their childbearing ages.
The transition occurred because males experienced higher mortality rates than females. In the 18th century British naval surgeon James Lind , through his studies of scurvy , added to the foundations of epidemiology. To study the prevention of scurvy, Lind conducted the first modern controlled clinical trial.
Selecting 12 sailors who were ill with scurvy, Lind divided them into pairs, each pair receiving a different dietary supplement. The symptoms of the sailors on the other dietary regimens , however, persisted. Also in the 18th century surgeon Edward Jenner , who practiced medicine in the village of Berkeley in Gloucestershire , England, observed that persons who developed cowpox a mild disease never contracted smallpox , a severe and often disfiguring and deadly disease.
Jenner decided to test his observation by using matter drawn from cowpox lesions on the hand of a dairymaid to inoculate a young boy against smallpox. When Jenner later exposed the boy to smallpox, the boy did not develop the disease.
In that way Jenner performed what later became one of the most widely known vaccination trials for smallpox. In time the practice of vaccinating for the prevention of smallpox became widespread, and vaccination in general became a widely used method to prevent the occurrence of many diseases.
Vaccination against smallpox was notably successful; by the disease had been declared eradicated. His most-important contribution to epidemiology was the establishment of a sophisticated system for classifying the causes of death. That enabled the comparison, for the first time, of mortality rates between different demographic and occupational groups.
A great pioneer in the field of epidemiology was English physician John Snow. Snow was well respected in London as a specialist in obstetric anesthesiology , having assisted Queen Victoria in the delivery of two of her children. Similar to other British physicians at the time, Snow became interested in the cause and spread of cholera epidemics that periodically occurred in London.
In , during the third epidemic to strike the city, Snow began his investigations. At the time, most physicians attributed the disease to miasma, or bad air, formed from the decay of organic matter. Snow, however, held the radical view at the time that cholera was caused by contact with germ-contaminated matter, particularly water. Snow identified a large number of deaths clustered around a public water hand pump on Broad Street in the Soho District of west London.
He informed the local authorities and explained his hunch as to the cause. Although the authorities were skeptical, the next day they had the pump disabled by removing its handle. Almost immediately, new cases of cholera started to dwindle. However, because cholera deaths were already declining in the city, Snow was unable to attribute the end of the outbreak directly to the removal of the pump handle.
Coronary heart disease is the leading cause of death worldwide, although its occurrence is unevenly distributed. It is one of the most common causes of death in North America and Europe. It was once relatively uncommon in Asia including China, Japan, and India , the…. The Southwark and Vauxhall Company drew its water from sewage-polluted inlets of the River Thames in London, whereas the Lambeth Company obtained its water from the upper portion of the river, some distance from urban pollution.
Snow showed that cholera deaths were higher for residents in homes served by the Southwark and Vauxhall Company than for residents in locations served by the Lambeth Company.
Because of his study methods and insight, Snow is generally regarded as the father of modern epidemiology. Epidemiology is based on two fundamental assumptions. First, the occurrence of disease is not random i. Second, the study of populations enables the identification of the causes and preventive factors associated with disease. To investigate disease in populations, epidemiologists rely on models and definitions of disease occurrence and employ various tools, the most basic of which are rates.
Epidemiologists often use models to explain the occurrence of disease. One commonly used model views disease in terms of susceptibility and exposure factors. In order for individuals to develop a disease, they must be both susceptible to the disease and exposed to the disease.
For example, for a person to develop measles rubeola , a highly infectious viral disease that was once common among children, the individual must be exposed to a person who is shedding the measles virus an active case and must lack immunity to the disease. Immunity to measles may be derived from either previously having had the disease or from having been vaccinated against it. Another commonly used model, the epidemiologic triad or epidemiologic triangle , views the occurrence of disease as the balance of host, agent, and environment factors.
The host is the actual or potential recipient or victim of the disease. Hosts have characteristics that either predispose them to or protect them from disease. Those characteristics may be biological e.
The agent is the factor that causes disease. Agents may be biological e. They also investigate unknown causes of adverse health effects, such as high incidences of cancer or autism in a particular community. Their research may involve ecologic investigations. Environmental epidemiologists also advise government agencies on acceptable levels of exposure to environmental contaminants. Public advisories about mercury in fish, high ozone days, and mold exposure are based on their work.
The vital work of these professionals helps protect the public from the harmful effects of environmental contaminants. Many also work for hospitals, or as faculty members or research staff at colleges and universities. A few others work in life science research and development. Others provide management, scientific, and technical consulting services, and some conduct research for health insurance and pharmaceutical companies.
Epidemiologists in research positions generally spend their time in offices, studying data and reports; lab work and data collection in the field is usually the responsibility of others. Epidemiologists working for government agencies, on the other hand, may often travel and collect data in the field and conduct environmental investigations. Due to extensive safety precautions, little risk is involved in fieldwork and sample collection. Most epidemiologists work full time during normal business hours, though they may work long or irregular hours during fieldwork or public health emergencies.
Develop and test hypotheses about populations and communities as they relate to health and disease. Second-tier epidemiologists have a breadth of experience that helps them become effective team leads or senior advisors to their workgroup. Accordingly, they may have more managerial responsibilities, such as:.
Epidemiology is the study and analysis of the distribution (who, when, and where ) and determinants of health and disease conditions in defined populations. Epidemiology is the study and control of disease or injury patterns in human populations. Epidemiologists do fieldwork to determine what causes disease. Epidemiology is considered a basic science of public health. Epidemiology is: a) a quantitative discipline built on a working knowledge of probability, statistics.