Table 1.
Potential risk factors based on the available data used in the analysis of risk factors in Slovakia, Romania and the Baltic States
| Name | Acronym | Description | Explanation | VIF Slovakia | VIF Romania | VIF Baltics | Source |
|---|---|---|---|---|---|---|---|
| Potential risk factors related to wild boar habitat | |||||||
| Wild boar suitability | WB_SUIT | Percentage of area with suitable habitat for wild boar | Habitat quality could drive wild boar density | 32.7 | 26.8 | 12.6 | ENETWILD‐consortium et al. (2020) |
| Waterbodies | Water | Percentage of waterbodies in the area | Wild boar could aggregate near waterbodies | 1.7 | 4.3 | 2 | https://www.esa‐landcover‐cci.org/?q=node/158 |
| Trees | Trees | Percentage of the area covered by trees | The land cover could have an impact on wild boar behaviour, e.g. some crops attract wild boar and would facilitate aggregation and impact on transmission rates | 1.4 | 2.5 | 1.1 | https://www.esa‐landcover‐cci.org/?q=node/158 |
| Crops | Crops | Percentage of the area covered by rain‐fed crops | 2.6 | 23.4 | 2.7 | https://www.esa‐landcover‐cci.org/?q=node/158 | |
| Herbaceous | Herb | Percentage of the area that is covered by herbaceous land cover | 43.2 | 7.9 | 3.6 | https://www.esa‐landcover‐cci.org/?q=node/158 | |
| Altitude | Altitude | Average altitude | Climatic conditions could have an effect both on the survival of the virus in the environment and on the wild boar habitat | 14.1 | 39.5 | 1.8 | https://lta.cr.usgs.gov/SRTM1Arc |
| Sun | Sun | Average yearly sun radiation | 16.5 | NA | 20.7 | https://worldclim.org/version2 | |
| Snow | Snow | Average yearly snow depth | 26 | 12.4 | 3.4 | Hall and Riggs (2015) | |
| Mean temperature | Temp | Average yearly mean temperature | 4.2 | 40 | 7.5 | https://worldclim.org/version2 | |
| Potential risk factors related to hunting activities | |||||||
| Wild boar abundance | WB_DNS | Wild boar hunting bag per surface (km2) | The number of wild boar hunted is correlated with the wild boar density in the area, both having an influence on the transmission rate | 2.3 | 37.6 | 1.1 |
Ministry of Agriculture and Rural Development of the Slovak Republic Ministry of Environment, Romania Ministry of Agriculture Latvia, Ministry of Environment, Estonia Ministry of Environment, Lithuania |
| Number of hunting dogs | Dogs_DNS | Number of hunting dogs per surface (km2) | The number of dogs used for hunting is a proxy of the hunting pressure and could influence wild boar behaviour | 3.9 | 6 | NA |
Ministry of Agriculture and Rural Development of the Slovak Republic Ministry of Environment, Romania |
| WB female | WB_Fe | Number of female wild boar hunted per surface (km2) | Hunting females is a sign of hunting for population control | NA | 41.7 | NA |
Ministry of Environment, Romania |
| Number of hunters | Hunters | Number of active hunters in the season per surface (km2) | The number of hunters is a proxy of the hunting pressure and could influence wild boar behaviour | NA | 2.2 | NA |
Ministry of Environment, Romania |
| Hunting days | Hdays | Number of hunting days | The number of hunting days is a proxy of the hunting pressure and could influence wild boar behaviour | NA | 4.1 | NA |
Ministry of Environment, Romania |
| Feeding places | Feed_P | Number of feeding places for the wild boar per surface (km2) | Feeding drives wild boar population dynamics and spatial aggregation | NA | 8.5 | NA |
Ministry of Environment, Romania |
| Feeding tonnes | Feed_T | Approximate tonnes of feed for the wild boar per surface (km2) | NA | 1.8 | NA |
Ministry of Environment, Romania |
|
| Average piglet | Piglets | Average number of piglets per sow | Piglets per sow is a proxy of wild boar reproductive success | NA | 4 | NA |
Ministry of Environment, Romania |
| Potential risk factors related to the pig farming system | |||||||
| Pigs density | Pig_DNS | Density of pigs per surface (km2) | Higher density of domestic pigs implies higher susceptible population for ASF | 1.8 | NA | 1.2 |
Ministry of Agriculture and Rural Development of the Slovak Republic Ministry of Agriculture Latvia, Ministry of Rural Affairs, Estonia Ministry of Agriculture Lithuania |
| Small farms density | SmallFarm_DNS | Density of small farms (< 10 pigs) per km2 | Small farms were assumed to often implement suboptimal biosecurity measures (Ribbens et al., 2008; Correia‐Gomes et al., 2017; Nurmoja et al., 2020) | 7.2 | NA | 346.8 |
Ministry of Agriculture and Rural Development of the Slovak Republic |
| Small farm pigs density | SmallPig_DNS | Density of pigs in small farms (< 10 pigs) per km2 | 6.1 | NA | NA |
Ministry of Agriculture and Rural Development of the Slovak Republic |
|
| Potential risk factors related to ASF in domestic population | |||||||
| ASF in domestic pigs | ASF_dom | Presence of a PCR‐positive result in domestic pigs in the district | The occurrence of ASF in domestic pigs in the district can be a proxy of the level of ASF contaminations in the area, and could be related to ASF in wild boar | 2.3 | 1.7 | NA |
Ministry of Agriculture and Rural Development of the Slovak Republic Ministry of Environment, Romania |
| Potential anthropogenic risk factors | |||||||
| Human footprint index | HFP | Average human footprint index per district | A higher human activity in an area could influence the occurrence of the disease | 4.1 | 24.8 | 2.2 | Venter et al. (2018) |
| Proportion of Urban habitat | Urban | Percentage of the surface occupied by urbanised areas | 3.8 | 33.1 | 1.5 | https://efsa.onlinelibrary.wiley.com/doi/epdf/10.2903/sp.efsa.2020.EN‐1871 | |
| Bare areas | Bare | Areas where the land is not covered by semi‐natural or artificial cover | 1.6 | 1.6 | 3.1 | https://www.esa‐landcover‐cci.org/?q=node/158 | |
NA, data not available or not calculated on this spatial level; variance inflation factor (VIF). Data in red: VIF > 5: excluded from analysis due to collinearity.