FIG 2.

Spatial and temporal dynamics of WNV in the United States. The occurrence and spatial distribution of the four proposed WNV genotypes over time: NY99 (red), Intermediate (yellow), WN02 (blue), and SW03 (purple). (Top) A phylogenetic tree (rooted by the NY99 genotype) was used to assist the interpretation of genotype spread. (Bottom, left) the prevalence of sequences sampled in different states per year. (Right) U.S. states colored per genotype, per year, according to the presence of WNV sequences.