Figure 5.

Census tract centroids where human WNV cases occurred, geomasked with random displacement within a 20 km × 20 km grid, during a cool period, September 2011 (red points) and a warm period, September 2014 (yellow points). Geographical expansion of cases in 2014 (yellow points) occurred in areas where transcritical variation between the cool and warm period occurred, either from the inhibitory to favourable (blue shading), or from the transitional to favourable (purple shading) temperature range. Areas with no shading within the black metropolitan LA boundary remained in the favourable range for the duration of both time periods. Random displacement of centroids within each grid square was restricted to locations with the same temperature shading as the true centroid. (Online version in colour.)