Fig. 1

Estimated transmission distances by scale of transmission. a Individual chikungunya cases are shown by date of symptom onset and estimated distance from its infector; transmission within the same building (i.e., at distance 0) is a special case of focal transmission and is displayed with a darker blue compared to other focal transmissions; red arrows at the top of the graph indicate cases transmitted locally over distances larger than the maximum scale of the graph; the timing of exported cases is indicated with vertical orange bars above the graph, and the size of the bar is proportional to the number of cases occurring on that day; the pink horizontal band at the bottom of the graph defines the radius of the buffer (200 m) surrounding a notified case within which insecticide treatments are conducted. b Distribution of the number of cases by transmission distance for different spatial scales; the x-axis is log-scaled. c Cumulative distribution of transmission distances for the focal component only; the 200-m treatment buffer is displayed