Drawing and Visualization

This drawing is from a video lesson that explores two important ways to measure how often a disease occurs: incidence and prevalence. Incidence is a rate, meaning it measures new cases of a disease over time. Prevalence is a proportion, meaning it counts all existing cases at a given moment. Using a simple island example, Professor Sue J. Goldie uses visuals, including a timeline, to break down how to calculate these numbers and explains the key difference—time matters for incidence, while prevalence is like a snapshot of all cases. 

In an introductory video that focuses on the transmission of infectious agents between humans, Professor Sue J. Goldie identifies the key steps in transmission using a visual schematic called the “chain of infection,” and defines different types and modalities of transmission. Simple models like this drawing can help learners ask the right questions and think strategically about interventions and policies.