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:
- Clinical care would be focused on helping an individual recover from a stroke, while public health would be focused on trying to improve eating habits nationally and reduce the number of strokes
- Clinical care would be focused on providing chemotherapy to help a lung cancer patient get their cancer into remission, while public health would be focused on reducing teen smoking so that those teens do not get lung cancer later in life
- Clinical care would be guiding the recovery of a child from a case of measles, while public health would be mandatory immunizations of all school-aged children
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.
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.
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).
Other milestones in public health include:
- 1918: The US federal government response to the global influenza pandemic (CDC 2019a)
- 1946: Opening of the US Communicable Disease Center, now the Centers for Disease Control and Prevention (CDC 2018a)
- 1948: Founding of the World Health Organization in 1948 (WHO 2019a)
- 1972: Passage of the US Clean Water Act, which led to dramatic improvements in water quality in rivers, lakes, and streams (EPA 2019)
- 1980: Smallpox eradicated globally as the culmination of a global immunization campaign started by the World Health Organization in 1958 (WHO 2019b)
- 1988: Beginning of the Global Polio Eradication Initiative (GPEI 2019)
- 2003: The global Severe Acute Respiratory Syndrome (SARS) epidemic is quickly recognized and controlled (CDC 2013)
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:
- Risk factors are characteristics that increase the likelihood of diease
- Protective factors are characteristics that decrease the likelihood of disease
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):
- How a person develops during the first few years of life (early childhood development)
- How much education a persons obtains
- Being able to get and keep a job
- What kind of work a person does
- Having food or being able to get food (food security)
- Having access to health services and the quality of those services
- Housing status
- How much money a person earns
- Discrimination and social support
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):
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:
- Surveillance
- Identify areas where a health problem is severe
- Identify areas where a health problem is increasing
- Identify vulnerable groups of people
- Analysis
- Determine relationships between risk/protective factors and health conditions
- Detect environmental contaminants and zoonotic vectors
- Development
- Determine locations where intervention testing should produce accurate results
- Implementation
- Create visualizations to support communication and advocacy
- Target implementation to areas of crisis
- Minimize shipment distance in disaster relief operation
- Guide efficient deployment of resources to maximize benefit and minimize cost
- Evaluate effectiveness of interventions
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.
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.
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:
- Community health specialists
- Dentists
- Dietitians and nutritionists
- Environmental science and protection technicians
- Health educators and community health workers
- Interpreters and translators
- Pharmacists
- Quality improvement coordinators
- Registered nurses
- Social and human service assistants
- Social workers
- Veterinarians
Those workers are directed by a hierarcy of experienced managers and administrators:
- Medical and health services managers
- Social and community service managers and directors
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.
- Epidemiologists
- Lawyers
- Microbiologists
- Political leaders
- Prevention specialists
- Public health consultants
- Sanitary engineers
- Urban and regional planners
- Research assistants
- Clinical research coordinators
For people pursuing careers in public health, a master's of public health degree is commonly required.
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