Fig. 4. Establishment of Am-ZIKV in the Americas.

The earliest inferred dates of lineage export to non-Brazilian regions, represented by box-and-whisker plots. Each plot corresponds to the earliest movement between a pair of locations with well-supported virus lineage migration. The first exports to South America outside Brazil (SA1 in Fig. 3), to Central America (CA1) and to the Caribbean (CB1) are shown in panels a–c, respectively. Box and whisker plots were generated in ggplot2, with boxes representing the median and interquartile ranges of the estimated date of earliest movement. In each of a–c, dashed lines show the estimated climatic vector suitability score for each recipient region, averaged across the countries for which sequence data is available (see Methods). In each of a-c, the bar plots show available notified ZIKV case data (plots adapted from PAHO) for the countries with the earliest confirmed cases (Colombia⁶¹ in panel a, Mexico⁶² in b, and Puerto Rico⁶³ in c). Coloured arrows indicate the earliest confirmation of ZIKV autochthonous cases in each non-Brazilian region. The vertical dashed line represents the date of ZIKV confirmation in the Americas.