Public Health and Epidemiology: Study Guide and Key Concepts

Overview of Public Health

Definitions and History of Public Health

Public health is the science and art of preventing disease, prolonging life, and promoting health through organized community efforts. Understanding its history and key concepts is essential for grasping its role in society.

• Common Elements in Definitions: Focus on population health, prevention, and organized efforts.

• Public Health vs. Medical Approach: Public health targets populations and prevention, while medicine focuses on individuals and treatment.

• Major Achievements in US Public Health: Examples include vaccination, sanitation, and control of infectious diseases.

• Historical Importance:

  • Snow: John Snow, known for tracing the source of a cholera outbreak in London.

  • Jenner: Edward Jenner, pioneer of the smallpox vaccine.

  • Chadwick: Edwin Chadwick, advocate for sanitation reform.

  • Semmelweis: Ignaz Semmelweis, promoted handwashing to prevent puerperal fever.

• Smallpox Eradication: A landmark public health campaign that led to the global eradication of smallpox.

• Evidence-Based Framework: Steps include Problem, Etiology, Recommendation, Implementation, and Evaluation. (Example: Reye's syndrome case study.)

Structure and Function of Public Health in the US

Organization and Essential Services

The US public health system is structured at federal, state, and local levels, each with specific roles and responsibilities.

• 10 Essential Services: Core functions that guide public health activities (e.g., monitoring health, diagnosing problems, informing the public).

• Federal, State, and Local Roles: Federal agencies provide funding and guidance; states coordinate programs; local agencies implement services.

• Key Agencies: DHHS, NIH, CDC, SAMHSA, FDA.

Social Determinants of Health (SDOH)

Impact of Social and Economic Factors

Social determinants are the conditions in which people are born, grow, live, work, and age, affecting health outcomes.

• Social-Ecological Model (SEM): Framework for understanding how individual, interpersonal, community, and societal factors influence health.

• Equality vs. Equity: Equality means giving everyone the same resources; equity means distributing resources based on need.

• Application: Use the social-ecological model to analyze health issues at multiple levels.

Epidemiology and Public Health Data

Measuring and Analyzing Disease

Epidemiology is the study of the distribution and determinants of health-related states in populations, and the application of this study to control health problems.

• Measures of Disease Frequency: Incidence (new cases), prevalence (existing cases).

• Types of Studies: Descriptive (who, what, when, where), analytic (why, how).

• Association and Causation: Understanding relationships between exposures and outcomes using measures like relative risk and odds ratio.

• Surveillance: Ongoing collection, analysis, and interpretation of health data.

• Case Definition: Standard criteria for classifying whether a person has a particular disease.

• Confounding: A situation where the relationship between exposure and outcome is distorted by a third variable.

• 2x2 Table: Used to organize data for calculating measures such as risk and odds ratio.

Example of a 2x2 Table for Disease Association

	Disease Present	Disease Absent
Exposed	a	b
Not Exposed	c	d

Relative Risk (RR):

$RR = \frac{a/(a+b)}{c/(c+d)}$

Odds Ratio (OR):

$OR = \frac{a \times d}{b \times c}$

Key Terms and Phrases

Essential Vocabulary for Public Health and Epidemiology

• Active Surveillance: Proactive data collection to monitor disease occurrence.

• Blinding: Concealing group assignment in studies to reduce bias.

• Burden of Disease: Impact of a health problem measured by financial cost, mortality, morbidity, or other indicators.

• Case Definition: Criteria for determining who has a disease.

• Causation: The relationship between cause and effect.

• Confounding: Distortion of the association between an exposure and outcome by a third variable.

• Determinant: Factor that influences health status.

• Disease Elimination: Reduction to zero of the incidence of a disease in a defined area.

• Disease Eradication: Permanent reduction to zero of the worldwide incidence of infection.

• Epidemiology: Study of the distribution and determinants of health-related states.

• Etiology: Study of the cause of disease.

• Evidence-Based: Using the best available evidence for decision-making.

• Exposure: Contact with a disease-causing factor.

• Incidence: Number of new cases in a population over a period of time.

• Miasma: Outdated theory that diseases were caused by "bad air."

• Morbidity: State of being diseased or unhealthy.

• Mortality: Death rate within a population.

• Passive Surveillance: Routine reporting of health data.

• Placebo: Inactive substance used as a control in experiments.

• Prevalence: Total number of cases in a population at a given time.

• Relative Risk: Ratio of the probability of an event occurring in the exposed group versus a non-exposed group.

• Risk: Probability of an event occurring.

• Risk Factor: Attribute or exposure that increases the likelihood of disease.

• Surveillance: Systematic collection and analysis of health data.

• Syndromic Surveillance: Monitoring symptoms to detect outbreaks early.

• Vaccination: Administration of a vaccine to stimulate immunity.

• Variolation: Early method of immunization using material from smallpox sores.