Fig. 1: Spatial and temporal distribution of local and imported cases of dengue fever, 2013-2020.

a Spatial distribution of local and imported dengue cases (log-transformed scale). The shades of red in the city blocks indicate the severity of local cases, with three breakpoints: 1.10, 3.22 and 5.88, while the shades of blue in the city blocks indicate the severity of imported cases, with three breakpoints: 0.69, 2.40 and 4.11. The Jenks natural breaking method was used for data classification. The blue dashed line is Hu Line, a geographical demarcation line for population distribution and economic development in China. b Seasonal distribution of dengue cases, plotted as the sum of the weekly number of cases throughout the year from 2013 to 2020. c Time series of weekly cases of dengue. For (a)–(c), natural logarithmic transformation (ln(cases + 1)) is applied. As a widely used data normalization method, logarithm transformation of data was performed to make the data distribution more uniform in order to better explore the seasonal fluctuation characteristics of dengue incidence. d Time series of weekly probable, clinically diagnosed and laboratory-confirmed cases of dengue. The subfigure providing a zoomed-in view of the weekly dengue cases on the vertical coordinate. e Source-sink relationships between original countries with imported dengue cases and Chinese provincial administrations with relatively high imported cases. f Relationships between original countries with imported dengue cases and Chinese provinces with relatively low imported cases. g Temporal distribution of imported dengue cases across provinces.