The Who, What, When, Where and Why questions of a disease outbreak need to be answered - in much the same way as a journalist investigates an new story.
Epidemiology is an essential tool for the study of the ecology and description of the natural history of disease, health surveillance, disease detection and disease outbreak investigation. What has been described as "shoe-leather" epidemiology refers to the door-to-door interviews that have been used to identify affected individuals (cases) and unaffected individuals (controls) in an outbreak or disease investigation. This type of epidemiological technique is invaluable in identifying risk facors and potential causes of disease.
W5 refers to the elements of a disease outbreak that need to be identified during an outbreak investigation:
Who - which animals are affected?
What - what is the disease of interest?
When - when did the outbreak start in time and has it spread?
Where - where did the outbreak start in terms of space and how has it spread?
Why - what was the cause of the disease outbreak?
Those that do disease investigation are often called medical detectives. W-Five was a news doucmentary show in Canada.
The principles of epidemiology are essential in clinical medicine because there are wide variations in the expression of disease between individuals. If all individuals responded identically to a disease or its treatment, then we would be able to do detailed experiments on one animal and know how to diagnose, treat and prevent that condition in all others of that breed.
Surveillance is the ongoing, and often continuous, collection, analysis, interpretation and communication of health information. Surveillance allows us to follow, in both time and space, the health status and risk factors associated with disease in a given population. The information obtained via surveillance can be used in the planning, implementation and evaluation of disease control schemes. Surveillance programs are be designed to meet a variety of objectives.
