Public Health and Epidemiology Overview

Clinical Approach

• Focuses on diagnosing and treating individual illnesses.
• Preventive measures (immunizations, etc.) are increasingly considered but still secondary to individual care.

Public Health Approach

• Aims to prevent and control diseases in populations.
• Includes tasks similar to medical practice, like identifying outbreak cases and managing diseases (tuberculosis, syphilis).

Epidemiology

• Studies the distribution and determinants of health and disease within populations.
• Investigates when, where, and how health problems affect specific populations to discover solutions.

Steps in Solving Health Problems

• Step 1: Collect Data: Surveillance—tracking disease cases; Time/Place/Person Analysis
• Step 2: Assessment: Identify patterns and trends.
• Step 3: Hypothesis Testing: Determine causality (how and why something happens).
• Step 4: Action: Implementing interventions, describing results

Analytical Epidemiology

• Aims to determine disease causes and develop effective interventions.

Purposes of Epidemiology in Public Health

• Identify factors (agent, host, environmental) affecting health.
• Determine the significance of different disease causes.
• Identify high-risk population segments.
• Evaluate public health program effectiveness.

Natural History and Spectrum of Disease

• Describes the progression of an untreated disease over time, noting individual variations and treatment impact.

Surveillance

• Collects information to guide public health policies and programs.
• Assesses public health status and evaluates programs.
• Prioritizes public health needs and stimulates research.
• Identifies patients and their contacts for intervention
• Detects epidemics, estimates disease prevalence, and measures trends.
• Monitors health practices, infectious/environmental agents, program effectiveness, and explores hypotheses.
• Involves emergency response systems (911, ambulances).

Types of Epidemiological Studies

• Cohort Study: Tracks exposed and unexposed groups to determine disease development.
• Case-Control Study: Compares previous exposures in cases with controls.
• Cross-Sectional Study: Examines simultaneous exposure and health outcome in a population sample.

Outbreak Investigation Steps

• Collect background information.
• Define the problem.
• Develop hypotheses.
• Design studies to test hypotheses.
• Collect and analyze data.
• Evaluate results.
• Formulate conclusions and reports.
• Confirm hypotheses via laboratory tests.

Understanding Epi Curves

• Graphs that illustrate disease occurrence over time.
• Reveal potential outbreaks: point source (all cases from a singular origin), continuous common source (cases over an extended period).
• Identify the source and duration of outbreaks.

Agent/Host/Environment Model

• Disease arises from the interaction of an infectious agent, host (patients), and the environment.

Calculations

• Attack Rate: Proportion of exposed individuals becoming ill.
• Relative Risk: Ratio of attack rates between exposed and unexposed groups.
• Data analysis uses 2x2 tables.

Bradford Hill Criteria

• Checklist to assess the likelihood of a causal relationship connecting factors to health outcomes.
• Elements include strength, consistency, specificity, temporality, biological gradient, plausibility, coherence, experiment.

Patterns for Presentation of Epidemiological Data

• Charts (BAR, PIE): Compare data, categorize information.
• Maps: Visualize geographic distribution of events, illustrate risk by population density.

Control Methods

• Control disease reservoirs (e.g., antibiotic treatment, screening).
• Control disease transmission (e.g., disinfection, vector control, hand hygiene, immunization).
• Prevention strategies include eradicating disease agents, strengthening immunity, controlling vectors, preventing contamination, and isolating infected individuals.