Strategic risk factor selection in disease risk mapping applied to the African swine fever outbreak in Sweden

Risk mapping in epidemiology is a strategic tool that identifies high-risk areas for disease outbreaks, guiding preventive, surveillance, and control measures. In this study, we investigated how the selection of risk factors in ASF risk mapping affected the output of risk maps using the outbreak in Fagersta, Sweden as a study area. We identified ASFV risk factors by considering the sequence of introduction, release, and spread. Introduction was linked to pathways through which the virus could enter new areas, while release was associated with human activities and infrastructure that may lead to environmental contamination. Spread was then examined in relation to wild boar populations and environmental conditions that influence virus transmission. We demonstrated how previously overlooked human activities, such as the management of residual waste in areas accessible to wild boar, contributed to the risk of ASF in Fagersta, an area classified as low risk, and how this affected the calculation of disease risk. This study emphasizes the need for robust risk assessment frameworks that take into account ecological and socio-demographic factors, as well as emerging research findings. In addition, the existence of region-specific threats or vulnerabilities point out the necessity of frequent revisions of risk maps by incorporating new threats or vulnerabilities and adapting regional features to environmental changes. These findings are meant to improve preparedness and response strategies for ASF and other infectious disease events, ultimately contributing to animal as well as public health protection.