Epidemiology Midterm Exam Review

Vocabulary practice flashcards covering epidemiologic concepts, formulas, screening metrics, surveillance types, and historical milestones from the Midterm Exam.

Positive Predictive Value (PPV)

A test validity measure focusing on positive screening test results; an $83\%$ PPV indicates that $83\%$ of individuals who test positive actually have the disease.

Negative Predictive Value (NPV)

A test validity measure focusing on negative screening test results; a $90\%$ NPV indicates that $90\%$ of individuals who test negative truly do not carry the target condition or gene.

Sensitivity

A test validity measure focusing on disease status that reflects the proportion of individuals with the disease who test positive (its denominator is all diseased individuals, or true positives plus false negatives).

Specificity

A test validity measure focusing on disease status that reflects the proportion of individuals without the disease who test negative (an $85\%$ specificity means $85\%$ of disease-free individuals test negative).

Crude Attack Rate

An epidemiologic measure of frequency used in a closed population, calculated by dividing the total number of individuals who became ill by the total number of individuals exposed.

Period Prevalence

An epidemiologic measure of frequency that quantifies existing cases of a disease over an extended period of time (more than $5$ days).

Point Prevalence

An epidemiologic measure of frequency assessing existing cases of a disease over a very short, specific point in time ($5$ days or less).

Disease Reservoir

Any living organism (such as humans or Aedes albopictus mosquitoes) or non-living environment in which an infectious pathogen normally lives and multiplies.

Case Fatality Rate

A mortality measure calculated by dividing the number of individuals who died from a specific disease by the total number of individuals diagnosed with that disease.

Passive Surveillance

A health surveillance approach where data collection relies on healthcare providers or patients reporting data during routine medical visits rather than active investigator outreach.

Direct Contact Transmission

The direct physical transfer of an infectious agent between hosts, such as transplacental transmission of Cytomegalovirus from mother to fetus or kissing an individual with strep throat.

Pathogenic Potential

A virulence component defined as an infectious organism's ability to cause severe damage to the host.

Dr. Ignaz Semmelweis

The historical figure who linked childbed fever in the 1850s to contaminated surgical instruments and inadequate hand hygiene among physicians and medical residents.

Natural Active Immunity

Immunity acquired through exposure to and recovery from a live natural infection (e.g., Bordetella pertussis), prompting the host's immune system to produce specific antibodies.

Artificial Active Immunity

Immunity induced by injecting a safe, weakened, or inactivated pathogen into an individual to stimulate the production of antibodies.

Koch's Postulates

A sequence of experimental steps establishing that a specific microorganism causes a specific disease by isolating it from a sick host, culturing it, infecting a healthy host, and re-isolating the identical organism.

Late Pathogenesis Phase

The phase in the natural history of disease marked by advanced clinical symptoms and disease progression where medical and tertiary interventions (such as cancer radiation) take place.

Kaplan-Meier Curve

A non-parametric visual statistic showing the probability of survival over defined time intervals for patients undergoing medical treatment.

Incidence Density

An epidemiologic measure of disease occurrence calculated for dynamic, open populations where the numerator is new cases and the denominator is total person-time at risk.

Infant Mortality Rate

A population health metric calculated as the number of deaths among infants aged $0\text{--}12$ months divided by the total number of live births during a specified period.

Maternal Mortality Rate

A vital health metric calculated by dividing maternal deaths resulting from childbirth-related complications by the total number of live births within a specified time frame.

Selective Screening

A targeted screening mechanism applied exclusively to high-risk population subsets, offering greater cost-effectiveness and time efficiency compared to mass screening.

Secondary Prevention

A level of public health prevention focusing on early disease detection and screening interventions (such as genetic testing for BRCA2 mutations) before symptoms manifest.