Wetenschappelijk artikelSpatial risk analysis for the introduction and circulation of six arboviruses in the Netherlands

Abstract Background: Arboviruses are a growing public health concern in Europe, with both endemic and exotic arboviruses expected to spread further into novel areas in the next decades. Predicting where future outbreaks will occur is a major challenge, particularly for regions where these arboviruses are not endemic. Spatial modelling of ecological risk factors for arbovirus circulation can help identify areas of potential emergence. Moreover, combining hazard maps of diferent arboviruses may facilitate a cost-efcient, targeted multiplex-surveillance strategy in areas where virus trans‑ mission is most likely. Here, we developed predictive hazard maps for the introduction and/or establishment of six arboviruses that were previously prioritized for the Netherlands: West Nile virus, Japanese encephalitis virus, Rift Valley fever virus, tick-borne encephalitis virus, louping-ill virus and Crimean-Congo haemorrhagic fever virus. Methods: Our spatial model included ecological risk factors that were identifed as relevant for these arboviruses by an earlier systematic review, including abiotic conditions, vector abundance, and host availability. We used geo‑ graphic information system (GIS)-based tools and geostatistical analyses to model spatially continuous datasets on these risk factors to identify regions in the Netherlands with suitable ecological conditions for arbovirus introduction and establishment. Results: The resulting hazard maps show that there is spatial clustering of areas with either a relatively low or rela‑ tively high environmental suitability for arbovirus circulation. Moreover, there was some overlap in high-hazard areas for virus introduction and/or establishment, particularly in the southern part of the country. Conclusions: The similarities in environmental suitability for some of the arboviruses provide opportunities for targeted sampling of vectors and/or sentinel hosts in these potential hotspots of emergence, thereby increasing the efcient use of limited resources for surveillance. Keywords: Risk mapping, Geographic Information System, West Nile virus, Japanese encephalitis virus, Rift Valley fever virus, Tick-borne encephalitis virus, Louping-ill virus, Crimean-Congo haemorrhagic fever virus, Vector-borne diseases