Mapping the potential distribution of the principal vector of Crimean-Congo hemorrhagic fever virus Hyalomma marginatum in Europe

Crimean-Congo haemorrhagic fever (CCHF) is the most widely distributed tick-borne viral disease in humans. The virus is widely expanded across western China, South Asia, and the Middle East to southeastern Europe and Africa. Its causative agent, Crimean-Congo haemorrhagic fever virus (CCHFV), is among the deadliest human pathogens in Africa and Eurasia. The historical known distribution of the CCHFV vector Hyalomma marginatum in Europe included most of the Mediterranean and the Balkan countries, Ukraine, and southern Russia. Further expansion of its potential distribution is possibly occurred in and out of the Mediterranean region. This study updated the map of the principal vector of CCHFV, H. marginatum , in the Old World. The model estimated the environmental suitability of H. marginatum in the Old World, including Europe. On the continental European scale, the model anticipated a widespread potential distribution, covering southern, western, central, and eastern Europe, as far north as southern parts of Scandinavian countries. The distribution of H. marginatum also covered the countries across the central part of Europe where the species is not autochthonous. All models were statistically robust and performed better than random (p < 0.001). Based on the results of the model, climatic conditions could hamper the successful overwintering of H. marginatum and their survival as adults in many areas of the region. Regular updates of the models, using updated occurrence, current, and future climatic data are recommended to regularly assess the areas at risk. Summary Hyalomma marginatum is a vector of numerous highly important human and animal pathogens. It is the main vector of Crimean-Congo haemorrhagic fever virus (CCHFV) in Europe. This study updated the potential distribution of H. marginatum on a global scale, including Europe, with a particular focus on Central Europe. The model predicted a widespread potential distribution of H. marginatum on the continental European scale, anticipating occurrences of H. marginatum in southern, western, central, and eastern Europe, as far north as southern parts of Scandinavian countries. In Central Europe, H. marginatum populations have not been established in any of the countries yet, but the presence of the species has been reported from all countries in the region. Their potential spread northwards and establishment of permanent populations of H. marginatum in the north are therefore of great importance, in particular since the immature stages of H. marginatum are frequently found on migratory birds flying northwards to temperate Europe. Our ecological niche model of H. marginatum in Central Europe anticipated its distribution in all countries of the region. Our prediction for current global potential distribution of this tick species can help in understanding disease risk areas associated with this vector.