Fig 1.
Under-surveilled area estimation flow.
The flowchart outlines the criteria used to define under-surveilled areas in this study, along with the methodology that informed this definition.
Fig 2.
Directional distribution of ASF-positive wild boar and the relationship between time and distance of the ASF event from the initial case in wild boar.
Each ellipse indicates the spatial distribution of ASF cases in wild boar over a three-month period (between October 2019 and March 2021). The graduated color of the ellipse represents the time lapsed from earlier (lighter) to more recent (darker). Three isolated groups (named A, B, and C) were observed at a distance from the ellipses. The scatterplot in the lower left shows the association between time elapsed and distance of ASF cases from the initial ASF-positive wild boar.
Table 1.
Results of Spearman’s rank correlation coefficients for the number of ASF cases and each variable.
Fig 3.
Estimation of the under-surveilled area in Gangwon-do, South Korea.
Red-colored areas are those with potential under-surveillance. The upper left and right figures are overlaid with ASF-positive wild boars in Gangwon-do as of 31 March 2021 and 13 January 2023, respectively. The lower left figure is overlaid with wild boar presence records. The lower right figure shows a map of the results obtained in Gangwon-do applied at the national level.
Table 2.
Results of the Chi-squared test of goodness of fit.
Fig 4.
The distance from the ASF-positive wild boar to the nearest water source and spatial network of the hydrological system in South Korea.
The line graph on the lower left shows the distance from the ASF-positive wild boar to the nearest water source in 100-meter intervals up to 1000 m. The map shows the developed network of hydrological systems in South Korea overlapping with the elevation map and ASF cases reported as of the end of March 2021.
Fig 5.
The Korean hydrological system.
The red line represents the downstream pathway of the potential risk of ASFV spread from North Korea to South Korea, i.e., the flow of water in the river. The flag symbols represent strategic drainage points for monitoring the risk of ASFV spread through rivers and watersheds. The green square indicates the starting point of the river (Water flow in rivers is from upstream to downstream due to gravity). The black arrow indicates the flow of water along gravity from North Korea through the DMZ to South Korea.