Science Olympiad - Disease Detectives (CDC'S PRINCIPLES OF EPIDEMIOLOGY GLOSSARY)

Active immunity

Your body makes its own antibodies after getting sick or vaccinated

Active surveillance

Health officials actively look for cases (they reach out)

Agent

The thing that causes disease (germ, chemical, toxin, etc.)

Age-adjusted mortality rate

Death rate adjusted so age differences don't mess up comparisons

Age-specific mortality rate

Death rate for one specific age group

Analytic epidemiology

Figuring out WHY disease happens (uses comparison groups)

Analytic study

Study that compares groups to find causes

Antibody

Proteins your blood makes to fight germs

Antigen

Foreign substance that triggers antibody production

Applied epidemiology

Actually using epidemiology to solve real health problems

Arbovirus

Virus spread by mosquitoes, ticks, or other bugs

Arithmetic mean

Regular average (add all numbers, divide by how many)

Arthropod

Bug with jointed legs (mosquitoes, ticks, flies, mites)

Association

Statistical relationship between two things

Asymmetrical distribution

Lopsided graph; mean, median, and mode are different

Asymptomatic

No symptoms (sick but doesn't feel sick)

Attack rate

Percent of people who got sick during an outbreak

Attack rate, secondary

How many contacts of sick people get sick

Attributable proportion

Percent of disease in exposed people caused by the exposure

Attribute

Personal characteristic (age, sex, genetics, etc.)

Bar chart

Graph with bars showing categories

Bias

Systematic error that makes results wrong

Bias, information

Error from collecting data wrong

Bias, selection

Error from choosing participants wrong

Bimodal

Two peaks in data

Biologic transmission

Vector carries germ AND germ grows/changes inside the vector

Birth cohort

Group born in same time period

Birth rate, crude

Number of births per 1,000 people

Box plot

Graph showing min, max, median, and quartiles with a box and whiskers

Carrier

Person who has germ and can spread it but isn't sick

Case

One instance of disease

Case-control study

Compare sick people to healthy people, look back at exposures

Case definition

Specific criteria to decide if someone has the disease

Case-fatality rate

Percent of sick people who die from that disease

Case, index

First case identified

Case-patient

Person with the disease in a study

Case, source

Person who spread infection to others

Cause, component

One factor that contributes to causing disease

Cause of disease

Factor that directly makes disease happen

Cause, necessary

Factor that MUST be present for disease to occur

Cause, sufficient

Factor(s) that ALWAYS causes disease when present

Census

Counting everyone in a population with details

Central location (central tendency)

The "middle" of data (mean, median, or mode)

Chain of infection

Path germ takes: reservoir → exit → transmission → entry → new host

Class interval

Range of values grouped together

Clinical criteria

Medical features used in case definition

Clinical disease

Disease with symptoms

Clinical trial

Experiment testing treatment on people

Cluster

Group of cases in same area/time

Cohort

Group with common experience followed over time

Cohort study

Follow exposed and unexposed groups, see who gets disease

Common-source outbreak

Everyone exposed to same source

Community immunity

See herd immunity

Community trial

Experiment on whole communities

Comparison group

Group you compare to the main group

Confidence interval

Range likely to contain true value (usually 95% sure)

Confounding

Third variable messes up the association you're studying

Contact

Person exposed to infection

Contact, direct

Touching infected person/animal/surface

Contagious

Can spread person-to-person

Contingency table

Two-variable cross-tabulation table

Continuous variable

Can have infinite values (height, weight, temperature)

Control

Person without disease in case-control study

Crude rate

Overall rate, not adjusted for anything

Cumulative frequency

Running total of frequencies

Death-to-case ratio

Deaths divided by total cases

Decision analysis

Using math to make decisions

Decision tree

Branching chart showing decision pathways

Demographic information

Personal characteristics (age, sex, race, location, job)

Denominator

Bottom number in fraction

Dependent variable

Outcome you're measuring

Descriptive epidemiology

Describing WHO, WHEN, WHERE disease occurs

Determinant

Factor that causes change in health

Direct transmission

Immediate transfer from source to person (touching, droplets)

Discrete variable

Limited number of possible values

Distribution

Frequency and pattern of values

Dose-response

More exposure = more disease (or less disease)

Dot plot

Graph with individual data points

Droplet nuclei

Tiny dried infectious particles that float in air

Droplet spread

Transmission through sneezes/coughs (short distance)

Effect

Result of a cause

Effectiveness

Does it work in real world?

Efficacy

Does it work under perfect conditions?

Efficiency

Does it work without wasting resources?

Endemic

Disease always present in an area at usual levels

Environmental factor

Outside factors affecting disease (climate, sanitation, etc.)

Epidemic

More cases than expected in area/time

Epidemic curve (epi curve)

Graph showing cases over time during outbreak

Epidemic period

Duration of epidemic

Epidemiologic triad

Agent + Host + Environment = Disease

Epidemiology

Study of disease distribution and causes in populations

Epidemiology, analytic

Finding WHY disease happens

Epidemiology, applied

Using epidemiology to solve problems

Epidemiology, descriptive

Describing patterns of disease

Epidemiology, field

Epidemiology done out in the community

Evaluation

Systematic examination of program/activity effectiveness

Excess risk

Extra risk in exposed group compared to unexposed

Experimental study

Researcher assigns exposures (like clinical trial)

Exposed group

Group that had contact with suspected cause

Exposure

Contact with cause of disease