Modelling the deathbed choices of ASF-infected wild boars depending on temperature in Belgium

Abstract

African swine fever (ASF) is a fatal viral disease that emerged in Kenya, affecting both pigs and wild boars regardless of sex and age. This disease appeared in September 2018 within the province of Luxembourg in Belgium, creating an outburst of contamination within suids. Research and disposal of ASF-infected wild boar carcasses is a crucial activity in order to control the spread of the virus and prevent its persistence in the environment. This study reveals the likely habitats used by these individuals to die based on air temperature. Three temperature-dependent habitat selection models (HSF) were calibrated to investigate the factors influencing the deathbed choices of diseased wild boars. These models were used to generate relative probability of occurrence maps over the study area. The results mainly showed a dependence on wetlands within low to medium slope deciduous forests. As temperature increased, mixed forests were preferred with a mild accentuation of these environmental factors, namely wetter and steeper conditions, showing a slight effect of heat on the selection of death sites. Furthermore, we showed that the number of positive carcasses detected varied seasonally, with more cases discovered in winter and autumn. So, these recommendations should allow the development of strategies to search for carcasses while minimizing the time spent in the field.