POE chapter 1

What is epidemiology?

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

What are the three key components of the definition of epidemiology?

Distribution, determinants, and application.

What does distribution mean in epidemiology?

The frequency and pattern of health-related events in a population.

What does determinants mean in epidemiology?

The factors or causes that influence the occurrence of health-related events.

What does application mean in epidemiology?

Using epidemiologic findings to prevent, control, or address health problems.

What are the five Ws of epidemiology?

What (health event), Who (person), Where (place), When (time), and Why/How (causes or contributing factors).

What is descriptive epidemiology?

The study of the distribution of disease by person, place, and time.

What is analytic epidemiology?

The study of the determinants or causes of disease by testing hypotheses and comparing groups.

What is the primary purpose of descriptive epidemiology?

To identify patterns, characterize health problems, and generate hypotheses.

What is the primary purpose of analytic epidemiology?

To test hypotheses and identify factors associated with disease occurrence.

What is a population in epidemiology?

A group of people who share one or more defined characteristics and are studied as a group.

Why is comparison important in epidemiology?

It helps determine whether disease occurrence differs between groups or from what would normally be expected.

What are the core epidemiologic functions?

Public health surveillance, field investigation, research, evaluation, and policy development.

What is a case definition?

A standard set of criteria used to determine whether an individual should be classified as having a particular disease or health condition.

What are the components of a case definition?

Clinical criteria, laboratory criteria when appropriate, and restrictions by person, place, and time.

Why should a case definition be applied consistently?

To ensure cases are classified uniformly and can be compared accurately.

What is the epidemiologic triad?

The model describing disease occurrence through the interaction of agent, host, and environment.

What are the three components of the epidemiologic triad?

Agent, host, and environment.

What is an agent?

A factor whose presence, absence, or characteristics are essential for a disease or health condition to occur.

What is a host?

A person or animal that can be affected by an infectious agent or other health hazard.

What is an environmental factor?

External conditions that influence the interaction between an agent and a host.

What is the natural history of disease?

The progression of a disease in an individual over time without intervention.

What are the stages of the natural history of disease?

Stage of susceptibility, subclinical disease, clinical disease, and recovery, disability, or death.

What is the stage of susceptibility?

The period before disease develops when a person may be at risk of developing the condition.

What is the subclinical stage?

The period after disease begins but before symptoms or signs become apparent.

What is the clinical stage?

The period when signs and symptoms of disease are present.

What is the chain of infection?

The sequence of events that allows an infectious agent to spread from one host to another.

What are the six links in the chain of infection?

Infectious agent, reservoir, portal of exit, mode of transmission, portal of entry, and susceptible host.

What is a reservoir?

The natural habitat in which an infectious agent normally lives, grows, and multiplies.

What is a portal of exit?

The route through which an infectious agent leaves its reservoir.

What is a mode of transmission?

The method by which an infectious agent spreads to a susceptible host.

What is a portal of entry?

The route through which an infectious agent enters a host.

What is a susceptible host?

A person or animal who lacks sufficient resistance to an infectious agent to prevent infection or disease.

What is direct transmission?

Transmission through immediate physical contact or direct exposure, such as touching, kissing, or contact with infectious droplets at close range.

What is indirect transmission?

Transmission through an intermediate vehicle, vector, or airborne route.

What is a vehicle in disease transmission?

An inanimate object or substance that carries an infectious agent, such as food, water, or blood.

What is a vector?

A living organism, often an arthropod, that transmits an infectious agent from one host to another.

What is an epidemic?

The occurrence of more cases of a disease or health event than expected in a particular area or among a specific group during a given period.

What is an endemic disease?

The constant presence or usual prevalence of a disease within a particular geographic area or population.

What is a pandemic?

An epidemic that has spread over several countries or continents and usually affects a large number of people.

What is a sporadic disease?

A disease that occurs infrequently and irregularly.

What is an outbreak?

An increase in disease cases above what is normally expected in a specific area or group; often used interchangeably with epidemic.

What is a cluster?

A grouping of cases in a particular time and place that may be greater than expected, even if the increase has not been established statistically.

What is an epidemic curve?

A graph showing the number of new cases of an illness by time of onset.

What is a common-source outbreak?

An outbreak in which people are exposed to the same source of infection or contamination.

What is a point-source outbreak?

A common-source outbreak in which exposure occurs over a relatively brief period.

What is a continuous common-source outbreak?

An outbreak in which exposure to a common source occurs over an extended period.

What is a propagated outbreak?

An outbreak resulting from person-to-person transmission, often producing successive waves of cases.