THE BED ROCK OF PUBLIC HEALTH

By Sanaa Imami and Sophie Hu

The field of epidemiology has a storied yet underappreciated history in the US. Epidemiology is the study of identifying the cause of disease and other various outcomes in specific populations. Epidemiology focuses on both the community and the patient or individual. The field is incredibly broad; studies can be scientific, systematic, and data-driven. The focus of these studies include the distribution and determinants of various health-related events in all ranges of populations from schools and small events to whole nations. The intrinsic value of epidemiology lies in its applicability for future events. Information learned from one health event can be applied in numerous others, which further emphasizes the versatility and importance of the field.

While epidemiology arose as a commonplace practice around the time of World War II, the inherent principles of the discipline can be traced back thousands of years. The first time these concepts were proposed was around 400 B.C., when Hippocrates, a physician and an incredibly profound figure in the history of medicine, proposed in his essay “On Airs, Waters, and Places” that illnesses could be influenced by environmental and host factors as opposed to supernatural forces, which was a radical idea at the time. The idea that disease and illness were not due to divine interference was an incredibly unpopular idea, but this concept was expanded upon throughout the following centuries. Similar to Hippocrates, John Snow also made groundbreaking contributions to the field. The anesthesiologist was later deemed “the father of field epidemiology” for his work in the 1800s. One of Snow’s most significant cases centered around the height of London’s cholera outbreak in 1854, when he proposed that the spread of disease could be linked to the city’s water supply. Snow identified a correlation to one of the pumps in the city, and confirmed his hypothesis by interviewing residents and determining that almost all of the cholera patients were getting their water supply from the same pump. After the pump was removed, the outbreak predictably ended. As the years went on, the study of epidemiology has grown and expanded to resemble the modern-day field that’s more well-known today. Following John Snow’s findings about the London cholera outbreak, various epidemiological practices were first implemented while investigating disease outbreaks and epidemics. In the mid-1900s, the definition of epidemiology expanded from solely the study of acute infectious disease to include noninfectious disease as well as violence, injury, and various other health-related illnesses and outcomes. Epidemiologists broadened their studies to focus on pressing health matters, like cancer and inheritable diseases. One notable study on cancer was conducted by Richard Doll and Bradford Hill in the UK in 1948. During the mid-1900s, lung cancer was a rapidly increasing health issue for both the British and Americans. Doll and Hill interviewed British lung cancer patients about their smoking use and compared the responses to that of a control group to see if there were any environmental factors that could be causing heightened levels of disease. Surely enough, Doll and Hill found a correlation between smoking and lung cancer levels. Patients with lung cancer levels. Patients with lung cancer were both more frequent and heavier smokers than those in the control group. This study was radical - until then, there were no assumed risks between smoking and cancer, and this link has remained incredibly significant today. In addition, the use of a control group in epidemiological studies was a practice that became frequently adopted after the publishing of Doll and Hill’s smoking study. This has vastly changed the way case studies are performed today. With the inclusion of a control group, researchers have been able to more conclusively establish causal relationships in case studies while further validating their hypotheses.

A significant part of epidemiological study is implementing preventative measures to eradicate disease. An example of this subfield of epidemiology put into practice was during the measles endemic. Before the creation of a measles vaccine, almost all children contracted the disease before they turned 15. In the 1950s and 60s, researchers developed several formulations of measles vaccines, some of which proved to be incredibly effective at preventing the contraction of measles. With the help of epidemiologists and government organizations like WHO and CDC, these vaccines were promoted and distributed to communities worldwide. These campaigns proved themselves to be extremely successful - by 2000, the US declared that measles had been eradicated on the national level, and measles outbreaks have greatly reduced since the inception of the vaccine, meaning that the disease only occurs in sporadic outbreaks. Campaigns and messaging like those implemented for the measles vaccine has since been utilized for other vaccinations and immunizations like the HPV and Meningitis B vaccines.

In recent years, the practice of epidemiology has been integral in managing the COVID-19 pandemic. As the pandemic began, epidemiologists have worked to trace the disease to its origin, looking for both the first reported patient and the source of the disease. Since then, epidemiologists have worked with the government to reduce transmission with public health policy and community-specific messaging. Most recently, with the development of several COVID vaccines, the CDC and other epidemiology-related organizations have focused on the distribution of these vaccines, ensuring that all communities have access to them. In the midst of the pandemic, the epidemiological field has been paramount in all fronts, whether through determining the source to fighting the spread of infection to working on prevention and distribution. The field of epidemiology is incredibly versatile and has grown immensely since the age of Hippocrates - as such, it has become synonymous with clinical practice while serving an integral role in the development of comprehensive, holistic views of disease and treatment.

Credits:

Centers for Disease Control and Prevention. (2012, May 18). Principles of Epidemiology | CDC. Centers for Disease Control and Prevention. Retrieved February 27, 2022, from https://www.cdc.gov/csels/ dsepd/ss1978/index.html

Prevention. (2020, November 5).