Epidemiology Quiz: Key Concepts

Introduction to Epidemiology II

• The course was held on October 30, 2024, at the University of Alberta.

Today's Objectives

• Define key terminology in epidemiologic methods
• Understand the difference between incidence and prevalence
• Understand the difference between active/passive surveillance, and screening
• Be able to create a case definition

Mode of Disease Transmission

• Direct transmission: Contact between individuals
• Example: (Not specified)
• Indirect transmission: Transmission via a common source (e.g., water source) or through a vector or fomite

Vector vs. Fomite

• Vector: Transmission via a living source (e.g., mosquitoes, ticks, fleas)
• Disease is not caused by the vector itself, but it spreads the disease
• Fomite: Transmission via a non-living source (e.g., contaminated needles, boots)

Are you a vector or a fomite?

• (This is a question posed in the lecture, likely as a thought-provoking exercise.)

More Terminology

• Endemic: Continuous source of a pathogen in a limited region
• Epidemic: Atypical increased occurrence of illness in a limited region
• Pandemic: Increased occurrence of illness crossing national borders
• Outbreak: Localized epidemic with a rapid increase in disease incidence

Types of Outbreaks

• Single point exposure: One source of exposure to the pathogen at a single point in time
• Multiple exposure: Multiple sources of exposure or different groups susceptible at different times
• Continuous exposure: A population is continuously exposed to a continuous source of disease
• Visual representations of each type are included in the lecture slides, showing different patterns of case numbers over time relative to exposure.

Measures of Occurrence

• Incidence: The number of new cases in a population at risk during a specific time period. Can account for risk and rate.
• Prevalence: The number of existing cases in a population at a specific time. Could be a single point or long-term measure.

When to Use What

• Prevalence: Useful for assessing population health status, planning for chronic diseases (not acute conditions)
• Incidence: Useful for investigating causation, prevention, and treatments, as well as planning and measuring repeated events.

Surveillance

• Systematic and continuous data collection, analysis, and interpretation
• Closely integrated with the timely and coherent dissemination of results, assessments to those who need the information. This allows for action to be taken.

Screening

• Presumptive identification of unrecognized disease or defect through testing, examinations, or procedures. These procedures can be rapidly applied.

Passive vs. Active

• Passive: Data from reportable diseases, reported by primary care providers, hospitals or other health care providers
• Inexpensive, but completeness and underreporting are potential issues.
• Active: Case finding, interviewing, reviewing medical records; visiting field sites. This is more expensive but can give more accurate reporting.

Creating a Case Definition

• Define how individuals/populations are affected through clinical signs
• Identify the causes (pathogen, causal factors)
• Define when they are affected (e.g., time, life stage)
• What characteristics of those affected (e.g., age, sex etc.)
• Where they are affected (location)
• Mode of transmission
• Incidence/prevalence

Test your knowledge on essential epidemiological terms and concepts with this quiz. Covering topics like endemic diseases, transmission types, and definitions of incidence, you'll explore fundamental aspects of this important field. Ideal for students in public health or related disciplines.