A comprehensive review of the emergence of Schmallenberg virus in Europe and its re-emergence in Ireland and the UK

Abstract

In recent decades vector-borne diseases have become increasingly prevalent as global warming continues, allowing vectors to expand into previously unoccupied regions. Since its emergence in Germany in 2011, Schmallenberg virus has spread throughout Europe. Initially, the spread was extremely rapid with the virus being detected in most European member countries one-year post-emergence. Culicoides biting midges were discovered to be the putative, biological vector for SBV. Transmission of the virus between countries was primarily attributed to the dispersal of vectors as a result of climatic conditions i.e. wind direction. Although, the transfer of viraemic animals may have also contributed to the spread. The prevalence of SBV can be monitored efficiently by bulk tank milk sampling and UV-trapping of Culicoides biting midges. Schmallenberg virus mainly causes acute, febrile symptoms in adult cows. In foetuses, it primarily manifests as Arthrogryposis-Hydranencephaly Syndrome (AHS), although some animals may present as anatomically normal with neurological defects. Economic losses are caused as a result of a drop in milk yield or of animals foregone due to foetal malformation.