Disease Detectives Terms

Science Olympiad

disease

Infection that results in signs (objective) and symptoms (subjective).

Opportunistic disease

A disease that causes sickness when given the opportunity of a damaged or weakened immune system.

Noscomial disease

An infection that is acquired in a hospital.

latrogenic disease

An illness that is caused by medication or a physician

Chronic infection

An infection where the agent is continuously present and detectable

Latent infection

An infection where the agent is continuously present, but can remain dormant before reactivation

Incubation period

Time in between when a person comes into contact with an agent of disease and when they first show symptoms or signs of disease

Latent period

Time in between when a person comes into contact with a pathogen and when they become infected

Asymptomatic

Displays no signs or symptoms, but is infected and can carry the disease

Susceptibility

To what extent a member of a population is able to resist infection

susceptible individual

A member of a population at risk of becoming infected by a disease

Pathogenicity

The property of causing disease following infection.

Virulence

The property of causing severe disease.

Infectivity

The property of establishing infection following exposure.

morbidity

The rate of disease in a population.

Mortality

The rate of death in a population.

Case fatality rate

The rate of death due to a disease in the diseased population.

Prevalence

The number of existing cases of disease in a given population.

Point prevalence

The number of existing cases of disease in a given population at a given point in time.

Period prevalence

The total number of cases of disease in a given population over a period of time.

Incidence

The rate of new cases of disease in a given population over a period of time.

Attack Rate

The number of people infected, divided by the total sample. There should be a high attack rate in those exposed and a low attack rate in those unexposed.

Person-time

The sum of the time during which each individual in a population was at risk for a disease.

Index Case

Also known as “patient zero”; the first case of a disease in a specific setting

Etiology

The cause of a disease.

Pathology

The science of the study and diagnosis of disease and injury.

Determinant

Any factor that brings about change in a health condition.

Herd immunity

A critical proportion of a population is immune to a disease such that the entire population is protected

Fulminant

A sudden and severe onset.

Quarantine

When you may have been exposed.

Isolation

When you have been exposed

Passive Surveillance

diseases are reported by healthcare providers; inexpensive, simple, BUT limited w/ incomplete reporting

Active Surveillance

Health agencies contact health provers seeking reports; often used w/ specific epidemiological investigation/during an outbreak

Syndromic Surveillance

signs of the disease (e.g., school absences or prescription drug sales) are monitored as a sign/proxy for the disease itself

Sentinel Surveillance

Professionals selected to represent a specific geographic area or group report health events to health agencies; used when high-quality data can't be obtained through passive surveillance; being able to implement intervention earlier and not being as reliant on doctors to diagnose disease, BUT not as effective for detecting rare diseases

Hill's Criteria for Causation

criteria that must be met to establish a cause-and-effect relationship

Koch's Postulates

criteria designed to establish a causal relationship between a causative microbe and a disease; has limitations since many pathogens do not fulfill all of the criteria

Convalescent Carriers/Vectors

Humans are also capable of spreading disease following a period of illness, typically thinking themselves cured of the disease

Incubatory Carriers/Vectors

When an individual transmits pathogens immediately following infection but prior to developing symptoms

Chronic Carriers/Vectors

Someone who can transmit a disease for a long period of time

Genetic Carriers/Vectors

has inherited a disease trait but shows no symptoms

Transient/Temporary Carriers/Vectors

Someone who can transmit an infectious disease for a short amount of time

Ecological Studies

looks for differences between groups of people with a shared characteristic rather than individuals

Cross Sectional Studies

a survey, health questionnaire, "snapshot in time"

Case-Control Studies

compare people with and without disease to find common exposures

Cohort Studies

compare people with and without exposures to see what happens to each; can be prospective or retrospective.

Randomized Controlled Trial Studies

human experiment that randomly assigns participants to an experimental or control group

Quasi Experiments Studies

research similarities with traditional experimental design or RCT, but lack element of random assignment to treatment/control; participants are assigned a group based on non-random criteria

FAT TOM

mnemonic device to describe six favorable conditions required for the growth of foodborne pathogens; acronym for food, acidity, time, temperature, oxygen, and moisture

Random error

result of fluctuations around a true value because of the sample population

Systematic error

any error other than random error; usually consistent and repeatable, often occurs from flawed equipment or experiment design

Selection bias

occurs when selection of participants for a study is affected by an unknown variable that is associated with the exposure and outcome being measured

Information bias

occurs when bias is introduced through an error in measurement or observation

Confounding bias

bias resulting from mixing effects of several factors; deals w/ causation and not variations in study results

Agent

microbial organism with the ability to cause disease

Reservoir

place where agents can thrive and reproduce

Portal of Exit

place of exit providing a way for an agent to leave the reservoir

Mode of Transmission

method of transfer by which the organism moves or is carried from one place to another

Portal of Entry

an opening that allows the microorganism to enter the host

Susceptible Host

person who cannot resist a microorganism invading the body, multiplying, and resulting in infection

Infectivity

capacity to cause infection in a susceptible host

Pathogenicity

capacity to cause disease in a host

Virulence

severity of disease that the agent causes to host

Primordial prevention

intervention at the very beginning to avoid the development of risk factors the population may be exposed to; deals with changing physical and social environments.

Primary prevention

early intervention to avoid initial exposure to agent of disease preventing the process from starting.

Secondary prevention

during the latent stage (when the disease has just begun), process of screening and instituting treatment may prevent progression to symptomatic disease

Tertiary prevention

during the symptomatic stage (when the patient shows symptoms), intervention may arrest, slow, or reverse the progression of disease

Quaternary prevention

set of health activities to mitigate or avoid consequences of unnecessary/excessive intervention of the health system

Active Immunity

occurs when the person is exposed to a live pathogen, develops the disease, and becomes immune as a result of the primary immune response

Passive Immunity

short-term immunization by the injection of antibodies, such as gamma globulin, that are not produced by the recipient's cells; naturally acquired passive immunity occurs during pregnancy, in which certain antibodies are passed from the maternal into the fetal bloodstream

herd immunity

protecting a whole community from disease by immunizing a critical mass of its populace; e.g.: vaccination protects more than just the vaccinated person

Point source epicurves

occur when people are exposed to the same exposure over a limited, well defined period of time —> commonly rises rapidly and contains a definite peak, followed by a gradual decline

Continuous common source

occur when the exposure to the source is prolonged over an extended period of time and may occur over more than one incubation period —> down slope of the curve may be very sharp if the common source is removed/gradual

Propagated (progressive source)

occur when a case of disease serves later as a source of infection for subsequent cases and those subsequent cases, in turn, serve as sources for later cases —> contains a series of successively larger peaks, as outbreak progresses, peaks flatten out

intermittent source

people are intermittently exposed to a source —> generally multiple peaks in this type of curve

Working Case Definition

Clinical information, Characteristics of Affected People, Place, Time

Confirmed cases

lab confirmation combined w/ signs and symptoms

Probable cases

signs and symptoms but no lab confirmation

Possible cases

some signs and symptoms, but unclear

Line listing

chart of cases including identifying information, clinical information, time, person, place, and risk factors.