Foundations and Applications of Public Health and Epidemiology

Public Health

The field of study that complements medicine, concerned with safeguarding and improving the health of a community as a whole.

Epidemiology

The study of the distribution and determinants of health-related states or events, and the prevention and control of health problems in human populations.

Community & Health Behavioral Promotion

The study of personal behaviors, how these behaviors influence health-related states or events in human populations, and how behaviors can be modified to prevent and control health problems.

Biostatistics

The study of the application of statistical methods to biological experiments.

Public Health Policy & Management

The study of the development and application of policy through assessment, policy development, and assurance.

Environmental Health Sciences

The study of how environmental exposures - industrialization, unplanned urbanization, effects of climate change and microbial and chemical contamination of water, air and food - affect human populations and contribute to disease.

Health

Health is a state of complete physical, mental, and social well-being and not merely the absence of disease to include body, mind, spirit.

5 constructs of health per the WHO

A healthy body, high-quality personal relationships, a sense of purpose in life, self-regarded mastery of life's tasks, resilience to stress, trauma, and change.

Influences on Human Health

Human health can be influenced by physical stresses such as climate change, chemicals such as the use of drugs, biological agents or pathogens, socioeconomic status, access to health care, and behavior.

Global Health

Global health is an area for study, research, and practice that places a priority on improving health and achieving equity in health for all people worldwide.

Epidemic

An outbreak is called an epidemic when there is a sudden increase in cases.

Pandemic

If an epidemic spreads across several countries and affects a large number of people, it is then classified as a pandemic.

Ebola virus

A recent epidemic that affected human populations.

Zika virus

A recent epidemic that affected human populations.

Influenza epidemic, 2009-2010

A recent epidemic that affected human populations.

Firearm mortality

A recent epidemic that affected human populations.

Opioid epidemic

A recent epidemic that affected human populations.

E. coli O157:H7

Outbreaks associated with this strain were part of recent epidemics.

2009 H1N1 Influenza

The initial cases were first identified in the U.S. and by summer 2010 the epidemic subsided; an estimated 60 million cases had occurred in the U.S.

2006 Outbreak of Escherichia coli

Outbreak during late summer and fall of 2006 affected 199 persons and caused 3 deaths.

Hemolytic-uremic syndrome (HUS)

A total of 31 patients (16%) were afflicted with this syndrome during the 2006 Escherichia coli outbreak.

Fresh spinach

Linked to the 2006 Escherichia coli outbreak.

Stage of susceptibility

The initial phase where an individual is at risk of developing a disease but has not yet been exposed.

Stage of pre-symptomatic disease

The phase where the disease is present but not yet symptomatic.

Stage of clinical disease

The phase where the disease is symptomatic and can be diagnosed.

Stage of recovery, disability, or death

The final phase where the individual may recover, experience disability, or die from the disease.

Primary Prevention

Strategies that seek to avoid the biological onset of disease.

Secondary Prevention

Strategies that seek to minimize adverse health outcomes through screening and early detection.

Tertiary Prevention

Strategies that seek to reduce further damage, disability, and risk of death in known disease cases.

Health Promotion

Efforts aimed at improving health and preventing disease.

Health Policy & Screening

Guidelines and regulations regarding the screening and prevention of diseases.

Example of Primary Prevention

Vaccination.

Example of Secondary Prevention

Screening.

Health policy related to screening considerations

Who should be screened? What diseases should we screen? What is the appropriate age when screening should occur? How should risk status influence screening?

Epidemiologic Transition

Describes changing patterns in population age distribution, mortality, fertility, life expectancy, and causes of death.

Mortality rates from infectious diseases

Have decreased over the past few centuries.

Chronic diseases

Include conditions like cancer and heart disease that last for long periods of time and progress slowly.

Degenerative diseases

Include conditions like mental decline, gout, and arteriosclerosis.

Communicable disease

An infectious disease that is spread from individual to individual.

Infectious diseases

Examples include pneumonia, tuberculosis, and diarrhea.

Non-communicable disease (NCD)

Not caused by infectious agents; can refer to chronic or degenerative diseases.

Children and young women

Showed the greatest improvement in survival due to their high susceptibility to infectious diseases.

Improvements in life expectancy

Due to behavior, cultural adaptations, eco biologic and socioeconomic factors, and advances in public health.

Examples of public health improvements

Include hygiene and nutrition, housing conditions, sanitation, water supply, antibiotics, and immunization programs.

Epidemiologic Advances

Studies show that many chronic diseases can be prevented and controlled by specific behaviors.

Maintaining a healthy weight

One of the behaviors that can help prevent chronic diseases.

Eating red meat

Should be limited to no more than two or three servings per week.

Taking a multivitamin with folate

Recommended to be taken every day for health.

Drinking alcohol

Should be limited to less than one drink per day.

High fiber foods

Recommended to be included in the diet for better health.

Not smoking

A behavior that helps prevent chronic diseases.

Getting adequate sleep

Important for maintaining health and preventing chronic diseases.

Protecting oneself from the sun

A recommended behavior to prevent health issues.

Exercising regularly

A key behavior for preventing chronic diseases.

Strategy Y

Used as a health promotion strategy that is 100% effective at preventing an irreversible mutation that results in cancer.

Strategy Z

Also used as a health promotion strategy that is 100% effective at preventing an irreversible mutation that results in cancer.

Population A

1,000 people without cancer and 200 people with an irreversible mutation that will result in cancer.

Population B

1,000 people without cancer and 400 people with an irreversible mutation that will result in cancer.

Epidemiologist's role

To interpret program effectiveness and evaluate health promotion strategies.

Disease frequency

How often a disease occurs varies by population.

Descriptive Epidemiology

Characterizes disease distribution in terms of person, place, and time.

Dynamic Population

An open population that is continually changing, allowing for both the addition of new members and the loss of previously entered members during the follow-up period.

Fixed Population

A closed group of individuals identified at some point in time and followed for a given period for detection of new disease.

Analytical Epidemiology

Focuses on determining the causes of health-related states or events.

Control of health problems

Involves identifying who is at greatest risk, where the problem is greatest, and when it is greatest.

Risk factors

Behaviors or conditions that increase the likelihood of developing a health problem.

Health interventions

Strategies implemented to improve health outcomes.

Population at risk

Groups of individuals who have a higher likelihood of experiencing a specific health issue.

Heart disease

A condition that occurs less frequently in Japan compared with the U.S. due to lower saturated fat intake.

Saturated fat intake

Dietary consumption of fats that can influence the risk of heart disease.

Influenza peaks

The occurrence of influenza is highest during the winter season.

Prostate cancer rates

Higher at greater latitudes compared to lower latitudes.

Health problems

Conditions that affect the health of populations and require assessment and control.

Policy development

The process of creating guidelines and regulations to improve public health.

Hypotheses generation

The process of forming theories based on observations in descriptive epidemiology.

Assessment in public health

The core function involving the identification of risk factors and health problems.

Epidemiology in the news

Recent examples that illustrate the application of epidemiological principles in current events.

Components of epidemiology

The essential elements that define the scope and purpose of epidemiological studies.

Basis of Epidemiology

Fundamental Assumptions: Disease does not occur by chance, Disease is not randomly distributed, Disease distribution is caused by 'something'.

Uses of Epidemiology

Study the natural history of a disease, Assess the health status of a population, Establish causation of a disease, Evaluate the impact of intervention.

Types of Epidemiology

Infectious disease epidemiology, Chronic disease epidemiology, Behavioral epidemiology, Environmental and occupational epidemiology, Clinical epidemiology, Genetic and molecular epidemiology, Social epidemiology, Applied epidemiology.

Examples of Epidemiology

Physical activity, walking, eating healthy, Safe sex education programs, Smoking cessation programs, Cancer screening such as mammogram, colonoscopy, Seatbelt laws, Food labeling, Vaccinations, Flu shots.

Epidemiologic Study Designs

Two types of epidemiologic studies exist: Descriptive studies and Analytic studies.

Person in Descriptive Epidemiology

Allows identification of frequency of disease and who is at greatest risk.

Place in Descriptive Epidemiology

Allows understanding of the geographic extent of disease, where the causal agent resides, and how the disease is transmitted.

Time in Descriptive Epidemiology

Allows description of the extent of the public health problem according to when and whether the health problem is predictable.

Descriptive Epidemiologic Studies

If a certain behavior such as a high-fat, low-fiber diet is more common where the frequency of colon cancer is greater, this may implicate diet as a possible causal factor.

Analytic Epidemiology

Analytic studies measure the association between a particular exposure and a disease to answer the 'How' of such events.

Exposures in Analytic Epidemiology

Include personal factors: smoking, diet, obesity, BMI, genetics; Environmental factors: asbestos exposure, air pollutants, radiation.

Not modifiable health-related risk factors

Genetics, age, gender, race.

Modifiable risk factors

Diet, smoking, environmental exposures, behavior.

Behavior as a risk factor

Behavior can be both a risk factor and outcome variable.

Causal link of risk factors

A risk factor directly increases the risk of a health outcome, implying a causal link.

5Ws of Epidemiology

What, Who, When, Where, Why.

High-fat, low-fiber diet

If more common where the frequency of colon cancer is greater, this may implicate diet as a possible causal factor.

Increased trend in smoking

If associated with an increased trend in coronary heart disease, this can implicate smoking as a possible causal factor.

Repetitive motion activity

If associated with an increase in carpal tunnel syndrome, then the activity is implicated as a possible causal factor.

Risk factor association

Is (Risk factor) associated with (Outcome)?

Physical inactivity

Largely associated with heart disease.

Public Health Epidemiology

Descriptive and analytic studies are used to monitor health in populations.