From Africa to Europe: the rise of epizootic haemorrhagic disease virus serotype 8.

Abstract

Since late 2022, epizootic haemorrhagic disease virus serotype 8 (EHDV-8) has emerged as a major threat to ruminant health in Europe, most likely introduced from North Africa through windborne Culicoides midges. The virus has caused extensive outbreaks in cattle and red deer across Italy, Spain, France, and Portugal, exposing vulnerabilities in current outbreak prevention and control measures. This review provides an updated overview of EHDV-8, focusing on its clinical presentation in domestic and wild ruminants, its recent geographic spread in Europe, and the rapid development of targeted vaccines. The European experience highlights the virus's capacity to induce substantial morbidity not only in cattle but also in wild and farmed cervid populations, particularly red deer. However, several aspects of EHDV-8 biology remain poorly understood, including host susceptibility and the mechanisms underlying viral overwintering. Furthermore, the limited availability of genomic data from Africa hampers efforts to trace the evolution and dissemination of EHDV. Strengthening collaboration with North African and Sub-Saharan countries will be crucial to enhance and harmonize surveillance systems across regions. Closing these knowledge gaps is essential for improving preparedness and response strategies, including the development of vaccines tailored to the serotypes currently circulating in endemic areas.