Epidemiology

What is epidemiology?

Epidemiology is a branch of medicine that studies health and disease in populations. The term epidemiology was derived from two Greek words: “epi” which means “on” and demos which means “population” or “people.” There are many infectious diseases such as cholera and Ebola which have the potential to kill a large number of people in a short period. As people today can easily travel from one continent to another, the pathogens can spread to all corners of the globe in a matter of hours or days. It is therefore very important for scientists to understand the causes and spreading mechanisms of these diseases so that they can terminate the transmission chains immediately and attempt to ensure that populations remain healthy. 

Even though epidemiology is mainly concerned with the “population aspect” of healthcare, this science is by no means less important than other branches of medicine. Epidemiology uses scientific findings from clinicians, medical trials, laboratory scientists, pharmacologists, and public health professionals, and applies them to a large number of people in areas affected by outbreaks. 

The study of epidemiology

Epidemiology uses two different methodological approaches: descriptive and analytical.

The descriptive approach is concerned with studying the distribution of different aspects of health over different parameters such as age, gender, ethnicity, sociodemographic factors, geographical area, or time. The data is collected through regular monitoring of public health records, notification systems, or specially designed epidemiological reports. Another way to collect the data about the health of our population is through population census. This method allows public health professionals to only use one small portion of the population called census population to get an accurate snapshot of the nation’s health. Health surveys are not only valuable for collecting the data about the current health status of our residents - these surveys also give scientists an opportunity to recognize future health challenges and create focused healthcare policies to address potential health problems before they appear.

The analytical approach is concerned with studying how different risk factors influence the probability that a certain health-related outcome would occur. Even though the study of the cause and its effects may sound simple, this is not always true for epidemiology. Analytical epidemiologists need to identify which causes inevitably lead to certain outcomes (sufficient causes) as well as which other factors contribute in the forming of such causes (component causes). For example, the flu cannot occur without the Influenza virus (a necessity cause), however, the Influenza virus can cause mild symptoms in some people, while causing death in others. The outcome of this infection will depend on various individual health components such as the immune status of the host or the existence of other diseases also known as co-morbidity. Analytical epidemiologists need to address all of these components to decrease the chance of adverse health outcomes.

The application of epidemiology

Epidemiological studies provide the valuable data that help healthcare professionals to monitor the health of populations. The data collected during descriptive epidemiological studies enable researchers to recognize the existing health problems and predict potential health outcomes that may appear sometime in the future. These data are then analyzed and quantified to create models that show how observed health outcomes may change over time so that the health policy stakeholders can make informed decisions about the need to create preventive programs. After the implementation of such programs, epidemiologists evaluate and monitor their efficacy and assess their sustainability over time.

Reference books and online resources:

Boslaugh, S., & Sage Publications, i. (2008). Encyclopedia of Epidemiology. Los Angeles: SAGE Publications, Inc.

Carneiro, I., & Howard, N. (2011). Introduction to Epidemiology. Maidenhead, Berkshire: McGraw-Hill Education.

Centers for Disease Control and Prevention: https://www.cdc.gov/

Fletcher, R. H., Fletcher, S. W., & Fletcher, G. S. (2014). Clinical Epidemiology: The Essentials. Philadelphia: LWW.

Infectious Disease Epidemiology. (2016). Oxford: Oxford University Press. doi:10.1093/med/9780198719830.001.0001

NHANES - National Health and Nutrition Examination Survey: https://www.cdc.gov/nchs/nhanes/index.htm

Porta, M. S., & International Epidemiological, A. (2008). A Dictionary of Epidemiology. Oxford: Oxford University Press, USA.

Saracci, R. (2010). Epidemiology: A Very Short Introduction. Oxford: Oxford University Press.

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