Disease Detectives 2025 Outbreak Investigation

Step 1: Collect Data

Gather surveillance data on time, place, person.

Step 2: Assessment

Make inferences based on collected data.

Step 3: Hypothesis Testing

Determine how and why the outbreak occurred.

Step 4: Action

Implement interventions to control the outbreak.

Experimental Studies

Research involving controlled experiments on subjects.

Clinical Trials

Experimental studies on individuals for treatment efficacy.

Community Trials

Experimental studies conducted on community populations.

Cohort Study

Tracks exposed participants to assess disease development.

Case Control Study

Compares exposure history between diseased and non-diseased.

Cross Sectional Study

Measures exposures and outcomes simultaneously in a population.

Ecological Study

Analyzes group-level data to compare health outcomes.

Scientific Method

Systematic approach for investigating phenomena and hypotheses.

Obtain Background Information

Gather existing knowledge relevant to the outbreak.

Define the Problem

Clearly articulate the health issue being investigated.

Formulate Hypothesis

Develop a testable statement based on observations.

Develop a Study

Create a method to test the hypothesis effectively.

Collect Data and Observations

Gather empirical evidence to support or refute hypothesis.

Evaluate Results

Analyze data to determine hypothesis validity.

Modify Hypothesis

Adjust hypothesis based on lab verification results.

Formulate Conclusions

Summarize findings and implications of the study.

Report Results

Communicate findings to relevant stakeholders and authorities.

Prepare for Field Work

Gather supplies and research before investigation begins.

Establish Existence of Outbreak

Assess severity and potential spread of health issue.

Verify the Diagnosis

Confirm diagnosis through proper testing and interviews.

Construct Case Definition

Define criteria for identifying affected individuals.

Case Definition

Criteria to determine disease presence.

Clinical Information

Details about the disease or condition.

Characteristics

Traits of affected individuals.

Location

Specific area of outbreak occurrence.

Time Sequence

Specific period of outbreak occurrence.

Identification of Cases

Counting specific cases of disease.

Confirmed Case

Diagnosis with lab verification present.

Probable Case

Diagnosis suggested but lacks lab verification.

Possible Case

Some evidence points to diagnosis.

Line Listing

Chart of specific cases with details.

Identifying Information

Case ID and personal identifiers.

Demographic Information

Age, sex, race, and occupation details.

Clinical Information (Line Listing)

Diagnosis, symptoms, and lab results.

Descriptive Time

Date and time of onset and report.

Descriptive Person

Age, sex, and other characteristics.

Descriptive Place

Specific location details of cases.

Risk Factors

Specific factors related to disease and outbreak.

Case Finding

Systematic search for cases.

Passive Reporting

Cases reported without active investigation.

Data Collection Form

Form for gathering case information.

Reporter Information

Source of case report details.

Descriptive Epidemiology

Analysis of data by time, place, and person.

Outbreak Investigation Forms

Documents used during outbreak analysis.

Epidemic Curve

Histogram showing disease outbreak over time.

Epi Curve

Visual representation of disease incidence.

X-axis

Represents time units in Epi curve.

Y-axis

Represents number of cases in Epi curve.

Single Peak

Indicates a single source of exposure.

Plateau

Shows continuous common source of infection.

Uniform Peaks

Indicates a propagated outbreak from person to person.

Geographic Extent

Area affected by the disease outbreak.

Spot Map

Visual tool to identify case locations.

Affected Population

Group identified by demographics or exposures.

Agent/Host/Environment Triad

Framework for understanding disease transmission.

Testable Hypothesis

Hypothesis must be verifiable through experimentation.

Cohort Study

Follows exposed and unexposed groups over time.

Retrospective Cohort

Looks back at past exposures to determine outcomes.

Prospective Cohort

Follows current exposures to future outcomes.

Attack Rate

Rate of illness in a specific group.

Relative Risk

Comparison of disease risk between exposed and unexposed.

Incidence Rate

Frequency of new cases in a population.

Control Group

Group not exposed, used for comparison.

Lab Verification

Scientific confirmation of hypothesis through testing.

High Attack Rate

Indicates significant illness in exposed group.

Low Attack Rate

Indicates minimal illness in unexposed group.

Positive Association

Increased risk indicated by relative risk > 1.0.

Negative Association

Decreased risk indicated by relative risk < 1.0.

Relative Risk

Used in cohort studies to measure risk.

Odds Ratio

Compares odds of exposure in cases vs controls.

Case-Control Study

Analyzes backward from effect to suspected cause.

Control Group

Similar characteristics to case group, not ill.

Odds Ratio Formula

Calculated as (a/c) / (b/d).

Case Patients

Individuals with the disease under study.

Control Patients

Individuals without the disease, used for comparison.

Random Error

Chance fluctuations affecting measurement precision.

Systematic Error

Consistent deviation from true population values.

Internal Validity

Accuracy of measurements within the study.

External Validity

Generalizability of study findings to the population.

Selection Bias

Bias from unmeasured variables affecting subject selection.

Information Bias

Systematic error in variable assessment.

Confounding

Extraneous factors affecting disease and exposure relationship.

False Relationships

Incorrect associations due to various errors.

Sample Size

Larger size reduces random error variability.

Hepatitis A Example

Case-control study linked infection to Restaurant A.

2x2 Table

Organizes data for case and control comparisons.

Odds of Exposure

Probability of exposure among case or control.

Bias Types

Different problems affecting study organization.

Measurement Validity

Degree of accuracy in study results.

Epidemiologic Study

Research examining health-related events and exposures.

Data Collection Errors

Mistakes during data gathering or analysis.

Information Bias

Systematic error in data collection affecting results.

Response Bias

Participants provide inaccurate or misleading responses.

Interviewer Bias

Interviewer influences participant responses unintentionally.

Recall Bias

Participants' memory affects accuracy of reported information.

Confounding

Mixing effects of extraneous factors on outcomes.