Epidemiology II Midterm 2 - University of Alberta - October 30, 2024 PDF

INTRODUCTION TO EPIDEMIOLOGY II October 30, 2024 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 defin...

INTRODUCTION TO EPIDEMIOLOGY II October 30, 2024 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 2 Mode of disease transmission Direct: contact must be made between individuals Example: ? Indirect: transmission via a common source (example: water source) Can be via a vector or a fomite 3 Vector vs. fomite Vector: transmission via a living source Disease is carried by vector but doesn’t cause disease NOT the same as cross contamination! Example: mosquitoes, ticks, fleas Example of vector borne disease? Fomite: transmission via a non-living source Example: contaminated needles, boots, etc 4 Are you a vector or a fomite? More terminology Endemic: continual source of a pathogen in a limited region Epidemic: atypical increased occurrence of illness in a limited region Pandemic: increased occurrence of illness that crosses national borders Outbreak: epidemic limited to a localized, rapid increase in the incidence of a disease 6 Types of outbreaks Single point exposure: one source of exposure to the pathogen at a single point in time 7 Types of outbreaks Multiple exposure: multiple sources of exposure or different groups are susceptible at different times 8 Types of outbreaks Continuous exposure: A population (or herd) is exposed to a continuous source of disease 9 Measures of occurrence Incidence: The number of new cases that occur in a population at risk during a specified period of time. Can account for risk and rate Prevalence: Number of existing cases in a population at a specific time Could be a single time point or a long term measure 10 When to use what Prevalence -Useful for assessing health status of population -Planning -Chronic diseases (not useful for acute conditions Incidence Investigating causation, prevention and treatments Planning Can measure repeated events 11 12 13 14 Creating a case definition How individuals/populations are affected → clinical signs What causes →pathogen, causal factors, etc When they are affected → time or life stage Who is affected → characteristic of those affected such as age, sex, etc Where they are affected → location ADD TO THAT -Mode of transmission -Incidence/prevalence 15 Please email if you have questions about midterm 2!