Disease Detectives – Part One: Background & Surveillance

Vocabulary flashcards covering foundational terms, historical figures, study types, surveillance methods, disease metrics, infection concepts, and public-health frameworks from the lecture notes.

Clinical Approach

Health-care practice focused on diagnosing and treating illness in individual patients, recently incorporating preventive medicine.

Public Health Approach

Discipline devoted to preventing disease and promoting health in populations through interventions on environment, behavior, lifestyle, and medical care.

Epidemiology

Study of the distribution and determinants of health-related states or events in specified populations and application of this study to control health problems.

Descriptive Epidemiology

Branch that characterizes health events by person, place, and time to generate hypotheses (answers who, what, when, where).

Analytic Epidemiology

Branch that tests hypotheses by comparing groups to identify causes and assess interventions (answers why and how).

Experimental Study

Epidemiologic investigation in which researchers deliberately control exposure (e.g., vaccine efficacy trial).

Observational Study

Epidemiologic investigation where exposures are not assigned by researchers; includes descriptive and analytic designs.

Surveillance

Ongoing, systematic collection, analysis, interpretation, and dissemination of health data for public-health action.

Passive Surveillance

Routine reporting of diseases by health-care providers; simple, inexpensive, but often incomplete.

Active Surveillance

Health agency–initiated contact with providers to solicit case reports; ensures more complete data, used during outbreaks or elimination efforts.

Sentinel Surveillance

High-quality data collection from selected sites or providers to monitor trends or key indicators when universal reporting is impractical.

Syndromic Surveillance

Monitoring of symptom patterns (e.g., school absenteeism, OTC sales) to detect or anticipate outbreaks before diagnoses are confirmed.

Endemic

Disease or condition constantly present in a population.

Outbreak

Localized increase in disease cases above expected levels in a specific area or group.

Epidemic

Large number of cases of a disease affecting a wide geographic area.

Pandemic

Epidemic occurring over several countries or continents and affecting a large proportion of the population.

Cluster

Aggregation of cases grouped in time and space, often of uncertain expected baseline (e.g., cancer cluster).

Sporadic

Disease that occurs infrequently and irregularly.

Risk

Probability that an individual will experience or die from an illness or injury within a specified period.

Rate

Number of cases during a specific time period divided by the population at risk in that period.

Ratio

Value obtained by dividing one quantity by another, often comparing two rates.

Proportion

Part divided by the whole (e.g., cases ÷ total population), no time dimension; expressed as decimal, fraction, or percentage.

Incidence

Number of new cases of a disease occurring in a population during a specified time period.

Prevalence

Total number of existing disease cases in a population at a given point or period in time.

Natural History of Disease

Progression of a disease in an individual over time without treatment, from susceptibility to outcome (recovery, disability, death).

Incubation Period

Time from exposure to an infectious agent to onset of symptoms.

Latency Period

Interval between exposure to a chronic-disease agent and appearance of symptoms.

Chain of Infection

Model outlining six links—agent, reservoir, portal of exit, mode of transmission, portal of entry, susceptible host—required for infection.

Agent

Microbial organism (e.g., bacteria, virus, parasite) capable of causing disease.

Reservoir

Place where an infectious agent normally lives, thrives, and multiplies.

Portal of Exit

Path by which an agent leaves its reservoir (e.g., respiratory tract, blood).

Mode of Transmission

Mechanism by which an agent is transferred from reservoir to host (e.g., airborne, vector-borne).

Portal of Entry

Site through which an agent enters a susceptible host (e.g., mucous membranes, skin break).

Susceptible Host

Person lacking immunity or resistance to an infectious agent.

Vector

Living organism that transmits an infectious agent to humans (e.g., mosquito carrying malaria).

Fomite

Inanimate object that conveys infectious agents between persons (e.g., contaminated comb).

Zoonosis

Infectious disease transmissible from animals to humans.

Infectious Dose

Number of microorganisms required to establish infection in a host.

Period of Communicability

Time span during which an infected person can transmit the agent to others.

Infectivity

Proportion of exposed individuals who become infected.

Pathogenicity

Proportion of infected individuals who develop clinical disease.

Virulence

Proportion of clinically ill individuals who become severely ill or die.

Health Determinants

Broad factors—genes & biology, health behaviors, social/environmental characteristics, access to care—that influence population health.

Health Impact Pyramid

Framework illustrating that population-wide environmental and policy actions have greater health impact than clinical interventions.

James Lind

1740s naval physician who conducted first controlled trial, proving limes prevented scurvy.

Edward Jenner

1790s physician who developed smallpox vaccine using cowpox exposure; pioneer of vaccination.

John Graunt

1662 London haberdasher who performed landmark mortality analysis, founding vital statistics.

William Farr

19th-century statistician, ‘father of modern vital statistics,’ advanced systematic collection and analysis of mortality data.

John Snow

1849-54 physician, ‘father of field epidemiology,’ linked cholera to contaminated water in London.

Louis Pasteur

1880s scientist who identified bacterial causes of diseases and developed anthrax vaccine.

Robert Koch

Microbiologist who formalized postulates for identifying infectious disease agents (1843–1910).

Joseph Goldberger

1920 researcher who demonstrated dietary cause of pellagra through descriptive field studies.

Framingham Study

Longitudinal cohort study (begun 1949) identifying cardiovascular disease risk factors.

Salk Polio Vaccine Trial

1954 field trial, largest formal human experiment, testing inactivated polio vaccine efficacy.

Mantel-Haenszel Method

1959 statistical procedure for stratified analysis in case-control studies.

Smallpox Eradication

1970s global public-health campaign culminating in elimination of smallpox from human population.

HIPAA

2000s U.S. Health Insurance Portability and Accountability Act, with implications for data privacy in epidemiologic research.

Surveillance Data Dissemination

Process of distributing analyzed health data via reports, alerts, journals, or media to stakeholders for action.

Link to Action

Final step in surveillance ensuring collected data lead to interventions and policy decisions.