Disease Detectives 2026

Plague

A serious, potentially life-threatening infectious disease that is usually transmitted to humans by the bites of rodent fleas. It was one of the scourges of our early history. There are three major forms of the disease: bubonic, septicemic, and pneumonic.

Ethiology

study of the cause of disease

Epidemiology

study of what causes disease, how disease is distributed, and how we can control spread of disease

Classical epidemiology

population oriented and studies community origins of health problems related to nutrition, environment and health behavior

Clinical epidemiology

studies patients in healthcare setting in order to improve diagnosis, treatment, and prognosis

Infectious disease epidemiology

heavily dependent on laboratory support

Chronic disease epidemiology

dependent on complex sampling and statistical methods

Descriptive epidemiology

considers time/place/person data on disease to determine trend, answers questions like who, what, where, when

Analytic epidemiology

involves hypothesis testing to determine cause of disease (causal relations), answers questions like why, how

Disease

infection that results in signs (objective) and symptoms (subjective)

Opportunistic disease

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

Noscomial disease

infection acquired in a hospital

Latrogenic disease

illness caused by medication or physician

Chronic infection

infection when agent is continously present and detectable

Latent infection

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

Incubation period

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

Asymptomatic

displays no signs/symptoms but is infected and can carry disease

Susceptibility

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

Susceptible individual

member of a population at risk of becoming infected by disease

Pathogenicity

the property of causing disease following infection

Infectivity

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

rate of death due to a disease in the diseased population

Prevalence

number of existing cases of diseases 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

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

Virulence

property of causing severe disease

Incidence

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 high attack rate for those exposed and low attack rate for those unexposed

Person-time

Endemic

Occurrence of expected number of cases among a group of people over time

Cluster

An aggregation of cases over a particular period closely grouped in time or space, regardless of whether the number is more than the expected number

Latrogenic

An illness that is caused by a medication or physician

Incubation Period

Time in between when a person comes into contact with a pathogen and when they first show symptoms or signs of disease. (INFECTIOUS)

Latent Period

Time in between when a person comes into contact with a pathogen and when they become infected. (CHRONIC)

Outbreak

More cases of a particular disease than expected in a given area or among a specialized group of people over a particular period of time.

Incidence

The # of new cases in a population

Prevalence

The # of cases in a population (per 10,000 or 100,000)

Vector

An animal intermediate that transmits a pathogen to humans but isn't the cause of the death itself

Fomite

A physical object that serves to transmit an infectious agent from person to person

Virulence

Degree or intensity of pathogenicity of an organism/Severity of disease that the agent causes to host

Compromised Host

Host with lowered resistance to infection

Nosocomial Infection

An infection that is traced back to a hospital

Infectivity

Capacity to cause infection in a susceptible host

Pathogenicity

Capacity to cause disease in a host

Reservoir

Site that harbors pathogenic organisms (human, animal, soil)

Outbreak Investigation Step 1

Prepare for field work

Outbreak Investigation Step 2

Establish the existence of an outbreak:

Outbreak Investigation Step 3

Verify the diagnosis

Outbreak Investigation Step 4

Construct a working case definition: establish with 4 criteria for determining who has disease - clinical information about disease, characteristics of affected people, location or place, time sequence

Confirmed cases

Lab confirmation combined with signs and symptoms.

Probable cases

Signs and symptoms but no lab confirmation.

Possible cases

Some signs and symptoms, but unclear.

Line listing

Chart of specific cases including information about each case: Identifying information, Clinical information, Descriptive: time, person, place; Risk factors and possible causes

Outbreak Investigation Step 5

Find cases systematically and record information. Info should be collected for each case: identifying information, demographic information, clinical information, risk factor info, reporter info

Outbreak Investigation Step 6

Perform descriptive epidemiology: consider time, place, person of outbreak, involves epi curves (time), spot maps (place), and case info (person)

Outbreak Investigation Step 7

Develop hypotheses: use agent/host/environment triad for hypothesis

Outbreak Investigation Step 8

Evaluate hypotheses epidemiologically: perform studies (case control or cohort) to validate a hypothesis

Outbreak Investigation Step 9

Reconsider, refine, and reevaluate hypotheses: use experimental data to narrow hypothesis

Outbreak Investigation Step 10

Compare and reconcile with laboratory and/or environmental studies: laboratory evidence is necessary to confirm a hypothesis

Outbreak Investigation Step 11

Implement control and prevention measures: goal is to disrupt chain of transmission

Outbreak Investigation Step 12

Initiate or maintain surveillance: evaluate the success of control and prevention measures

Outbreak Investigation Step 13

Communicate findings: can include an oral briefing, written report, PSA

PulseNet

network of labs across US that helps epidemiologists identify new foodborne disease outbreaks, automatically reporting data in real time to CDC, relies on early detection/reporting and hyper specific DNA fingerprinting, rapid and precise, able to facilitate implementation of specific control and prevention measures, stopping outbreak spread

PulseNet Surveillance Step 1

Person falls ill and visits doctor

PulseNet Surveillance Step 2

Doctor suspects foodborne illness and asks for sample (usually stool) which is sent to lab at clinic or hospital

PulseNet Surveillance Step 3

Clinical laboratory processes sample to isolate bacteria that is making patient ill ex. salmonella

PulseNet Surveillance Step 4

Clinical lab notifies doctor who tells patient and discuss treatment options, clinical lab also sends sample to local or state public health lab

PulseNet Surveillance Step 5

Public health lab determines what kind of bacteria (salmonella) it is

PulseNet Surveillance Step 6