a-IPC Terminology Review

Incidence

Number of NEW cases of a given disease in a given time period

Prevalence

Number of EXISTING cases of a given disease at a give time.

Endemic

The usual incidence of a given disease within a geographical area during a specified time period. Also referred to as baseline of the disease

Epidemic

An excess over the expected incidence of disease within a given geographical area during a specified time period. Note: not defined on the absolute number of cases but on the number of cases in comparison to what is expected.

Pandemic

An epidemic spread over a wide geographical area, across countries or continents.

Outbreak

An infection event characterized by a notable, often sudden increase in the number of cases of a disease, above the expected norm of a given population, or the presence of unusual microbes.

Cluster

A group of persons with a given disease occurring in the same space and time.

Vector

In biology, a living thing (i.e. insects, rodents, birds, plants, or humans) that carry an infectious agent of pathogen to a susceptible host, such as human-to-human or from a bloodsucking insect to humans.

Reservoir

A place in which an infectious agent can survive but may or may not multiply. i.e., Pseudomonas in nebulizers and Hep B on the surface of a hemodialysis machine.

Zoonosis

A disease transmitted from animals to humans

Fomite

An inanimate object on which organisms may exist for some period of time, for example a contaminated piece of medical equipment

Herd immunity

the resistance of a group to invasion and spread of an infectious agent, based on the immunity of a high proportion of individual members of the group (i.e, mass vaccination campaigns)

Risk

The probability or likelihood of an event occurring

Risk Factor

A characteristic, behavior, or experience that increases the probability of developing a negative health status

Colonization

The presence of microorganisms in or on a host with growth and multiplication but without tissue invasion or damage or the clinical evidence of disease I

Infection - unapparent, asymptomatic, or subclincal

An infection that runs a course similar to that of clinical disease but below the threshold of discernible clinical symptoms. Host appears well, they may serve as a silent or unapparent disseminator of the infectious agent (asymptomatic i.e. Typhoid Mary)

Infecion - Apparent, clinical, or symptomatic

An infection that results in clinical signs and symptoms of a recognizable disease process

Healthcare-associated infections (HAI)

An infection that is not present at the time of admission to a healthcare facility but is temporally associated with admission to or a procedure performed in the facility. An infection present at the time of admission may also be healthcare-associated if it is related to a recent encounter with a healthcare environment

Community-Acquired infections (CAI)

An infection that is typically present within 48 hours of admission to healthcare facility and has association with a recent encounter with a healthcare environment

Contamination

The presence of an infectious agent on a body surface or inanimate object. Inanimate objects include but are not limited to textiles, hard surfaces, medical equipment, wound dressings, and food and beverages.

SSI’s

Surgical Site Infections

HCPs

Health Care Personnel

IPs

Infection Preventionist

Causative agent

A biological, physical, or chemical entity capable of causing disease

Reservoir (3 common reservoirs, naturally and healthcare)

• A place in which infectious agents can survive but may or may not multiply.

• Naturally: Humans, animals, and the environment

• Healthcare: Patients, HCP, Healthcare equipment and environment

Carrier (example)

• A person who shows no recognizable signs or symptoms of a disease but is capable of spreading the disease to others.

  • Example: Healthcare worker with group A streptococcus

Convalescent carriers (example)

• Those who recovered from the disease but still have organisms present that can be transmitted.

  • Example: C. difficle can be shed for long periods of time

Chronic carriers/sustained carriers (example)

• May continue to have organisms present for very long periods of time

  • Example: Typhoid Mary

Intermittent carriers

Periodically shed organisms

Portal of exit (Examples)

• Path by which the infectious agent leaves the reservoir

  • Example: Respiratory, genitourinary, gastrointestinal tract. skin/mucous membranes, transplacental, blood

Mode of transmission

Method by which organism reaches susceptible host

Direct transmission

person-to-person spread with actual physical contact occurring between host and susceptible host

Indirect transmission

An individual comes in contact with a contaminated intermediate object or fomite.

Droplet transmission

An infectious agent travels on relatively large respiratory droplets that people sneeze, cough, or exhale.

• The most efficient means of airborne transmission is by droplet nuclei

Airborne spread

May involve varying distances between the source and the host

• Nuclei (often called aerosols) can vary from 1 to 5 um and be suspended in air for extended periods of time

• Aerosols generating procedures, such as nebulizer treatments and bronchoscopy, may result in aerosolization of organisms not normally transmitted through aerosols.

External vector-borne transmission

Is the mechanical transfer of microorganisms by a vector, such as fly on food

Internal vector-borne transmission

Involves the transfer of infectious material directly from the vector into the new host. i.e., malaria and mosquitoes.