Key Concepts in Epidemiology and Public Health

Epidemiology Basics:

• Studies health events among populations, not individuals.
• Focused on monitoring disease incidence, prevalence, and mortality rates.

Public Health Role:

• Aim to maintain population health and prevent negative health outcomes.
• Informed by epidemiological studies, such as dietary impacts on health.
• CDC tracks various health metrics, including cancer, maternal mortality, and Infectious diseases.

Historical Figures:

• Florence Nightingale: Improved sanitary conditions in hospitals during the Crimean War, attributing outcomes to hygiene rather than battlefield wounds.
• John Snow: Identified the water source of the 1854 cholera epidemic through mapping cases in London.

Key Epidemiological Concepts:

• Prevalence: Total existing cases in a population.
• Incidence: New cases over a specified time period.
• Mortality Rate: Deaths in a population from a specific cause.

Types of Diseases:

• Endemic: Steady frequency in a specific location (e.g., malaria in the South U.S.).
• Epidemic: Rapid increase in cases within a local population.
• Pandemic: Widespread epidemic across multiple continents.
• Sporadic: Occasional outbreaks with no consistent pattern.

Disease Transmission Dynamics:

• Point Source Epidemic: Single source exposure (e.g., contaminated food).
• Common Source Epidemic: Continuous exposure over time (e.g., water supply).
• Propagated Epidemic: Person-to-person transmission, leading to exponential growth.

Factors Influencing Spread:

• Cultural practices, population density, and seasonal changes affect epidemic patterns (e.g., winter spikes for respiratory diseases).

Testing & Screening:

• Screening Tests: Quick, non-invasive tests to identify health issues.
• Diagnostic Tests: More invasive, fewer false positives/negatives, e.g., biopsies.

Causation in Epidemiology:

• Koch's Postulates: Framework for determining disease causation, now supplemented by modern molecular methods like PCR.

Current Challenges:

• Emerging and re-emerging diseases linked to climate change and global travel (e.g., increased Lyme disease cases in the Midwest).
• Vaccine adverse events tracking to monitor vaccine safety (VAERS).

Important Numbers:

• R-naught Value (R0): Measures infection spread potential. COVID ~2, Measles ~16.
• Case Fatality Rate: Proportion of deaths among diagnosed cases, assists in evaluating disease impact.