Students of journalism are taught that an excellent news story, whether it be about a bank robbery, dramatic rescue, or presidential candidate’s speech, have to encompass the 5 W’s: what, that, wbelow, when and also why (sometimes cited as why/how). The 5 W’s are the essential components of a news story bereason if any of the 5 are absent, the story is incomplete.

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The same is true in characterizing epidemiologic events, whether it be a break out of norovirus among cruise ship passengers or the usage of mammograms to detect early on breast cancer. The distinction is that epidemiologists tfinish to usage synonyms for the 5 W’s: diagnosis or wellness occasion (what), perkid (who), place (where), time (when), and also causes, threat components, and settings of transmission (why/how).

Words public health comes from the Greek words epi, interpretation on or upon, demos, interpretation world, and logos, interpretation the research of. In other words, the word epidemiology has actually its roots in the study of what befalls a population. Many meanings have actually been proposed, yet the adhering to definition captures the underlying values and also public wellness spirit of epidemiology:

Epidemiology is the study of the distribution and also determinants of health-connected says or events in stated populations, and the application of this examine to the manage of health problems (1).

Key terms in this interpretation reflect some of the essential ethics of public health.


Epidemiology is a clinical self-control through sound approaches of scientific inquiry at its foundation. Epidemiology is data-pushed and depends on a systematic and also unbiased strategy to the repertoire, evaluation, and interpretation of information. Basic epidemiologic techniques tend to depend on cautious monitoring and also use of valid comparikid groups to assess whether what was oboffered, such as the variety of cases of illness in a certain area during a specific time duration or the frequency of an exposure among persons through illness, differs from what might be supposed. However, epidemiology additionally draws on methods from other clinical areas, including biostatistics and informatics, with biologic, economic, social, and behavioral scientific researches.

In fact, epidemiology is often described as the standard science of public wellness, and also for great reason. First, epidemiology is a quantitative discipline that depends on a working understanding of probability, statistics, and also sound research methods. 2nd, public health is a method of causal reasoning based on emerging and also experimentation hypotheses grounded in such scientific areas as biology, behavioral scientific researches, physics, and also ergonomics to define health-connected actions, says, and events. However, epidemiology is not just a study task yet an integral component of public health and wellness, offering the structure for directing practical and also appropriate public wellness action based on this science and causal reasoning.(2)


Epidemiology is came to through the frequency and pattern of health and wellness events in a population:

Frequency refers not only to the number of health and wellness occasions such as the number of situations of meningitis or diabetes in a population, however also to the connection of that number to the dimension of the populace. The resulting rate permits epidemiologists to compare condition event across various populations.

Pattern describes the incident of health-connected events by time, place, and perkid. Time patterns might be annual, seasonal, weekly, day-to-day, hourly, weekday versus weekfinish, or any kind of other breakdvery own of time that might affect illness or injury incident. Place trends encompass geographical variation, urban/rural distinctions, and area of work sites or colleges. Personal features include demographic components which may be concerned risk of illness, injury, or discapacity such as age, sex, marital status, and also socioeconomic condition, as well as actions and eco-friendly exposures.

Characterizing wellness events by time, place, and also perboy are activities of descriptive epidemiology, disputed in more detail later in this leschild.


Determinant: any type of aspect, whether event, characteristic, or various other definable entity, that brings around a readjust in a health condition or other characterized characteristic.

Epidemiology is additionally supplied to search for determinants, which are the reasons and also various other determinants that influence the occurrence of illness and other health-connected occasions. Epidemiologists assume that condition does not occur randomly in a populace, yet happens just once the right buildup of threat determinants or determinants exists in an individual. To search for these factors, epidemiologists usage analytic public health 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 qualities, hereditary or immunologic make-up, behaviors, environmental exposures, or various other so-dubbed potential hazard components. Ideally, the findings carry out enough proof to straight prompt and reliable public health and wellness control and prevention measures.

Health-connected states or events

Epidemiology was initially concentrated specifically on epidemics of communicable diseases (3) however was ultimately expanded to address endemic communicable diseases and non-communicable transmittable conditions. By the middle of the 20th Century, added epidemiologic techniques had actually been occurred and applied to chronic diseases, injuries, birth defects, maternal-child health, work-related health, and also eco-friendly health. Then epidemiologists began to look at actions related to wellness and health, such as amount of exercise and also seat belt use. Now, with the recent explosion in molecular techniques, epidemiologists deserve to make vital strides in examining hereditary markers of disease hazard. Undoubtedly, the term health-related says or occasions might be seen as anything that affects the health of a populace. Nonetheless, many kind of epidemiologists still usage the term “disease” as shorthand also for the wide array of health-associated claims and events that are stupassed away.

Specified populations

Although epidemiologists and also straight health-treatment suppliers (clinicians) are both pertained to via incident and manage of illness, they differ considerably in exactly how they see “the patient.” The clinician is came to about the health of an individual; the epidemiologist is concerned around the cumulative health of the world in a area or population. In various other words, the clinician’s “patient” is the individual; the epidemiologist’s “patient” is the community. Therefore, the clinician and also the epidemiologist have actually various duties as soon as challenged via a perkid via condition. For instance, as soon as a patient through diarrheal disease presents, both are interested in developing the correct diagnosis. However, while the clinician generally concentrates on treating and also caring for the individual, the epidemiologist focuses on identifying the expocertain or resource that brought about the illness; the number of other persons that may have actually been similarly exposed; the potential for additionally spcheck out in the community; and also interventions to prevent extra instances or recurrences.


Epidemiology is not just “the examine of” wellness in a population; it additionally involves using the knowledge got by the studies to community-based exercise. Like the practice of medication, the exercise of epidemiology is both a scientific research and also an art. To make the correct diagnosis and prescribe appropriate treatment for a patient, the clinician combines clinical (scientific) knowledge with endure, clinical judgment, and also expertise of the patient. Similarly, the epidemiologist provides the scientific approaches of descriptive and analytic epidemiology as well as experience, epidemiologic judgment, and also expertise of neighborhood conditions in “diagnosing” the wellness of a community and also proposing correct, helpful, and also acceptable public health and wellness interventions to manage and proccasion condition in the community.


Epidemiology is the study (clinical, methodical, data-driven) of the distribution (frequency, pattern) and also factors (reasons, danger factors) of health-connected states and also events (not just diseases) in specified populations (patient is neighborhood, people regarded collectively), and also the application of (considering that public health is a discipline within public health) this examine to the control of health and wellness troubles.

Exercise 1.1

Below are three crucial terms taken from the interpretation of epidemiology, complied with by a list of activities that an epidemiologist could perform. Match the term to the activity that best explains it. You need to match only one term per task.

____ 1. Compare food histories between persons through Staphylococcus food poisoning and those without____ 2. Compare frequency of brain cancer among anatomists with frequency in general population____ 3. Mark on a map the residences of all youngsters born via birth defects within 2 miles of a hazardous waste site____ 4. Graph the number of instances of congenital syphilis by year for the country____ 5. Recommfinish that cshed contacts of a child newly reported via meningococcal meningitis get Rifampin____ 6. Tabulate the frequency of clinical indications, symptoms, and also laboratory findings among kids through chickenpox in Cincinnati, Ohio

Check your answer.

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References (This Section)

Last JM, editor. Dictionary of epidemiology. 4th ed. New York: Oxford University Press; 2001. p. 61.Cates W. Epidemiology: Applying ethics to clinical exercise. Contemp Ob/Gyn 1982;20:147–61.Greenlumber M.Epidemics and also crowd-diseases: an advent to the examine of public health, Oxford College Press; 1935.