Detection of West Nile virus via retrospective mosquito arbovirus surveillance, United Kingdom, 2025
Robert C. Bruce, Anthony J. Abbott, Ben P. Jones, B. Gardner, Estela González, Andra‐Maria Ionescu, Madhujot Jagdev, Ava Jenkins, Mariana Santos, Katharina Seilern‐Macpherson, Hugh J. Hanmer, Robert A. Robinson, Alexander G. C. Vaux, Nicholas S. Johnson, Andrew A. Cunningham, Becki Lawson, Jolyon M. Medlock, Arran J. Folly
Abstract
In March 2025, as part of ongoing enhanced surveillance for mosquito-borne Orthoflaviviruses, West Nile virus (WNV) RNA was detected in two pools of female Aedes vexans collected in July 2023 in Nottinghamshire, England. Sequencing and phylogenetic analysis of a 402 bp fragment indicate clustering with WNV lineage 1a. The exact origin of this virus remains unclear, but this finding indicates a historic WNV presence in the United Kingdom. Surveillance has not provided evidence of further WNV transmission to date.