Epidemiology: A boon bestowed to mankind

By- Mahima Kumari

Madhura Mandlik

Epidemiology in the simplest of terms is the basic science of preventive and social medicine. The word itself comes from the Greek epi ‘upon, among’, demos ‘people, district’, and logos ‘study, word, discourse’, suggesting that it applies only to the human population.

It is an important part of public health and helps shape policy decisions and evidence-based practice by identifying risk factors for disease and targets for preventive healthcare. The people who specialize in epidemiology are called epidemiologists, and they help with study design, data collection, it’s statistical analysis, and the interpretation and dissemination of obtained results.

The major areas of epidemiology are disease causation, transmission, outbreak investigation, disease surveillance, environmental epidemiology, forensic epidemiology, occupational epidemiology, screening, biomonitoring, and comparisons of treatment effects such as in clinical trials. It relies heavily on other scientific disciplines like biology to better understand disease processes, statistics to make efficient use of the data and draw appropriate conclusions, social sciences to better understand proximate and distal causes, and engineering for exposure assessment.

Epidemiology has been documented through the ages. The first attempt was made by Hippocrates in 400 B.C, who attempted to explain disease occurrence from a rational rather than a supernatural viewpoint. In his essay entitled “On Airs, Waters, and Places,” Hippocrates suggested that environmental and host factors such as behaviors might influence the development of disease. Several other notable people are John Grant, who published a landmark analysis of mortality data in 1662, and William Farr who then built upon Graunt’s work by systematically collecting and analyzing Britain’s mortality statistics.

But the most important person in the history of epidemiology has to be John Snow, an anesthesiologist in the mid- 1800’s who would revolutionize the field and come to be known as the father of field epidemiology. One of his most famous investigations is the one done in 1854 at a time when an epidemic of cholera was ravaging Golden Square of London. Using his methods he was able to discover the cause of the disease and prevent its recurrence. He began his investigation by determining where in this area persons with cholera lived and worked. He marked each residence on a map of the area, this type of map, showing the geographic distribution of cases, is called a spot map.

On this spot map, he marked the location of water pumps present in the area, since he believed that water was the source of infection. He discovered that out of the three pumps present in the area, one was more frequently used and had a cluster of cases surrounding it. To confirm his suspicions, he questioned residents of the area with cholera about where they had drunk water from. After Snow presented his findings to municipal officials, the handle of the pump was removed and the outbreak ended.

In the mid-and late-1800s, epidemiological methods began to be applied in the investigation of disease occurrence. though they were focused on acute infectious diseases, this range was finally extended to non-infectious diseases in the 1930s and 1940s. After World War II an explosion in the development of research methods and our knowledge of epidemiology was seen. Epidemiology was then applied to the entire range of health-related outcomes, behaviors, and even knowledge and attitudes. One of epidemiology’s greatest achievements was seen during the 1960s and early 1970s when epidemiological methods were used to eradicate smallpox worldwide.

In the Eighties, medicine was extended to the studies of injuries and violence. While within the Nineties, the connected fields of molecular and genetic medicine took root. Meanwhile, infectious diseases continued to challenge epidemiologists as new infectious agents emerged (Ebola virus, (HIV)/ (AIDS)). And ever since the terrorist attacks of 2001, epidemiologists have had to contemplate deliberate transmission of diseases through biological warfare and terrorism.

Epidemiology is important in healthcare for it can be used to understand the pathogenesis of diseases, improve diagnostic accuracy, help the patient reduce risk factors, and assist the physician in choosing the correct therapeutic approach. The Framingham heart study is one such exemplary study that has paved the way for understanding cardiovascular diseases. It is a population-based study that began in 1948 and has become an ongoing observational longitudinal study.

The importance of epidemiology can’t be understated, especially during the COVID-19 pandemic, which has brought it into the forefront or as an April 2020 University of Southern California article noted “The coronavirus epidemic… thrust epidemiology – the study of the incidence, distribution and control of disease in a population – to the forefront of scientific disciplines across the globe and even made temporary celebrities out of some of its practitioners.”

Epidemiology has been taken for granted for a long time. It’s like an underdog running silently behind all of us, remaining one of the strongest pillars of health and healthcare bolstering our fight, helping us understand new diseases every day.