This chart displays the total number of illnesses caused by disease outbreaks, aggregated by month and colored by primary transmission mode. It uses a bar chart where each bar represents a month, with the height showing the summed illness count and the color distinguishing different modes of transmission. The visualization renders with Vega-Lite, configured through the Vega-Lite API, and loads its data from a remote CSV file using d3.csv. Interactive tooltips reveal the specific transmission mode on hover.