Applied Epidemiology is the science dealing with the spread and control of diseases and other factors relating to health in populations and other groups.
Epidemiological information is used to identify and evaluate the risks of epidemic outbreaks of disease and to help prevent their spread or return.
The role of epidemiologist in public health :
Epidemiology relates to specific populations as well as specific diseases. Epidemiologists do a number of things to investigate both the health threat and the population affected:
They collect and interpret data about incidences of, for example, a particular disease and the people who have it. The data used can be statistics such as mortality rates and incidences of disease. It can also be in the form of surveys designed to gather information about a population, such as their lifestyle or ethnicity.
Some statistics are gathered from the whole of the target population, but more often observations can only be made on a study sample, which is selected from the target population.
The sample is chosen at random from a study population, which can be identified on the basis of location, occupation, age, sex, lifestyle, diagnosis or treatment—or some combination of these.
Such studies can provide clues to the cause and mode of transmission of a disease. For example, comparing incidences of lung cancer in smokers and non-smokers showed a correlation between smoking and lung cancer.
Epidemiologists also monitor trends over time. These longitudinal studies can identify emerging health issues and assess the effectiveness of control measures, such as vaccination.