Introduction to Public Health

This tutorial introduces basic concept of public health, and is partially derived from the CDC's Introduction to Public Health.

The Purpose of Public Health

In 1920, CEA Winslow, then chairman of the Yale Medical School, published a paper containing a definition of public health that is still commonly used today:

"Public health is the science and the art of preventing disease, prolonging life, and promoting physical health and efficiency through organized community efforts..."

This focus on society as a whole rather than individuals contrasts public health with individual health (clinical care):

Public Health Clinical Care
Population focus Patient focus
Public ethics Personal behaviors
Prevention Diagnosis/treatment
Field studies Patient studies
Research training Clinical training
Public sector Private sector

For example:

Historical Examples of Public Health

The roots of public health arguably extend back into antiquity. Religious traditions and texts (such as the Hebrew Torah and Hindu Upanishads) commonly have specific requirements or prohibitions regarding diet, cleanliness, and sexual behavior. While these requirements are often framed in terms of obedience to divine commands, functionalist theories of religion (i.e. Durkheim 1912) point out the broader implications of these practices for health in the community. These ancient laws have contemporary secular counterparts in nutrition and hygiene guidelines and programs, as well as efforts to control the spread of sexually-transmitted disease.

Moses with the Ten Commandments (Philippe de Champaigne 1648)

The Greeks and Romans built massive public works for providing fresh water into cities and carrying sewage away, dramatically improving the health of the population. These ancient engineering feats have contemporary counterparts in wastewater treatment and waste management practices.

Roman Aqueduct at Pont du Gard, France (Song 2014)

The modern era of public health is commonly traced to the the UK Public Health Act of 1848, which was a response to the horrific health problems created by urbanization associated with the industrial revolution in England. The act created a boards of health that oversaw "water supplies, sewerage, control of offensive trades, quality of foods, paving of streets, removal of garbage, and other sanitary matters." While the boards did not have the political power or material resources to fully address most of these problems, this act was a transition from reactive to proactive government intervention, and a key step in the evolution of local government responsibility for public health that has yielded health benefits we often take for granted in the developed world (Fee and Brown 2005).

Cover of Charles Dickens' A Tale of Two Cities (Browne 1858)

Other milestones in public health include:

Polio Vaccination in Sweden (Berling 1957)

Determinants of Health

Determinants of health are "factors that contribute to a person’s current state of health. These factors may be biological, socioeconomic, psychosocial, behavioral, or social in nature" (CDC 2014).

These factors can be positive or negative:

Determinants of health are a product of ecology, which is "the totality or pattern of relations between organisms and their environment" (Merriam-Webster 2019a). These ecological relationships include social relationships. Social determinants of health include (CDC 2014):

The Public Health Approach

For the purposes of this tutorial, public policy is defined as "a system of laws, regulatory measures, courses of action, and funding priorities concerning a given topic promulgated by a governmental entity or its representatives" (Kilpatrick 2000).

The ultimate objective of public health policy is usually the implementation of interventions, which are acts "performed for, with, or on behalf of a person or population whose purpose is to assess, improve, maintain, promote, or modify health, functioning, or health conditions" (WHO 2020).

In public health, the formation of policy goes through four steps, commonly referred to as the public health approach (CDC 2019b):

The Public Health Approach

Public Health and Geospatial Data

The what is where aspect of geospatial data and GIS can be an extremely valuable public health tool at all phases of the public health approach:

GIS is especially useful in epidemiology, the branch of medical science that deals with the incidence, distribution, and control of disease in a population (Merriam Webster 2019b).

One of the pioneering examples of the use of geospatial data for epidemiology was in mid 19th century London, long before GIS or electronic information technology existed. Cholera is an often fatal bacterial infection of the small intestine that is spread by water contaminated with sewage (CDC 2018b). London at the time of the industrial revolution was densely populated, with poor sanitation and pollution control, and serious cholera outbreaks were common.

John Snow was a London doctor who suspected, correctly and contrary to common beliefs of the time, that cholera was associated with drinking water. With the help of local clergy, in 1854 Snow mapped where cholera victims lived, and noted a cluster of cases surrounding a water well on Broad Street (surveillance). Snow had the handle of the pump removed, forcing local residents to use other, non-contaminated wells (intervention). This intervention resulted in an immediate reduction in new cholera cases.

Snow is often considered the father of modern epidemiology, and modern variations on Snow's technique are still used to assist in identifying causes of disease outbreaks. The location of that long-gone well is now 39 Broadwick Street ( 51.513329, -0.136727), and Snow's pioneering work is celebrated with a plaque and, appropriately, a pub bearing his name.

John Snow's 1854 Map of Cholera in London (Snow 1855)

The Impact of Public Health Policy

As with many things in life, the overall public impact of those policies tends to be proportional to the difficulty needed to implement them and the amount of individual effort required for positive response.

Policy Impact vs Effort

Jobs in Public Health

There are a wide variety of jobs available in public health.

Working on the front lines are people from a variety of medical specialties that help successfull implement public health policies:

Those workers are directed by a hierarcy of experienced managers and administrators:

The public health policy those front line workers implement is developed by an equally diverse set of professionals. This is the area of public health where GIS can be most useful.

For people pursuing careers in public health, a master's of public health degree is commonly required.


Berling, Ingemar. 1957. "Polio vaccination started 1957 in Sweden. The photo shows the nurse Birgit Rutberg vaccinate Nils Birger Linderholm in February 1957." Accessed 16 July 2019.

Browne, Hablot Knight. 1858. "Cover of serial Tale of Two Cities by Charles Dickens." London: Chapman and Hall.

Centers For Disease Control and Prevention (CDC). 2013. "About Severe Acute Respiratory Syndrome (SARS)." Accessed 6 July 2019.

Centers for Disease Control and Prevention (CDC). 2014. "NCHHSTP Social Determinants of Health." Accessed 5 July 2019.

Centers for Disease Control and Prevention (CDC). 2018a. "Our History - Our Story." Accessed 5 July 2019.

Centers for Disease Control and Prevention (CDC). 2018b. "Cholera - Vibrio Cholerae Infection." Accessed 16 July 2019.

Centers for Disease Control and Prevention (CDC). 2019a. "1918 Pandemic (H1N1 virus)." Accessed 5 July 2019.

Centers for Disease Control and Prevention (CDC). 2019b. "The Public Health Approach to Violence Prevention." Accessed 5 July 2019.

Commission on Social Determinants of Health (CSDH). 2008. "Closing the gap in a generation: health equity through action on the social determinants of health. Final report of the Commission on Social Determinants of Health." Geneva: World Health Organization.

Durkheim, Emile. 2012. "The Elementary Forms of the Religious Life." Translated by Joseph Swain. London: George Allen and Unwin Ltd.

Environmental Protection Agency (EPA). 2019. "History of the Clean Water Act." Accessed 6 July 2019.

Fee, Elizabeth and Theodore M. Brown. 2005. "The Public Health Act of 1848." Bulletin of the World Health Organization 83 (11), 866-867.

Global Polio Eradication Initiative (GPEI). 2019. "History of Polio." Accessed 5 July 2019.

Institute of Medicine. 1988. "The future of public health." Washington, DC: National Academy Press.

Kilpatrick, Dean. 2000. "Definitions of Public Policy and the Law." Accessed 4 July 2019.

Merriam-Webster. 2019a. "Ecology." Accessed 5 July 2019.

Merriam-Webster. 2019a. "Epidemiology." Accessed 5 July 2019.

Philippe de Champaigne. 1648. "Moses with the Ten Commandments - WGA04717." Accessed 16 July 2019.

Snow, John. 1855. "On the Mode of Communication of Cholera," 2nd edition. Lithograph by C.F. Cheffins. London: John Churchill.

Song, Benh Lieu. 2014. "Pont du Gard." Accessed 16 July 2019.

Winslow, C.E.A. 1920. "The Untilled Fields of Public Health." Science 51 (1306): 23-33. Accessed 11 September 2019.

World Health Organization (WHO). 2019a. "Who We Are." Accessed 5 July 2019.

World Health Organization (WHO). 2019b "Emergencies preparedness, response: Smallpox."

World Health Organization (WHO). 2020. "International Classification of Health Interventions (ICHI)." Accessed 8 February 2020.