UK SCIENTISTS have detected traces of West Nile virus in mosquitoes for the first time, though experts stress that the risk to the public remains very low.
The discovery was made by the UK Health Security Agency (UKHSA) and the Animal and Plant Health Agency (APHA) through the Vector-Borne RADAR programme, which monitors insect-borne diseases. Genetic fragments of the virus were identified in two pools of Aedes vexans mosquitoes collected in July 2023 from wetlands along the River Idle in Nottinghamshire. The virus, usually spread among birds by mosquitoes, can occasionally infect humans or horses, though no local human or equine cases have ever been recorded in the UK. A total of 200 mosquito pools were tested, with only two returning positive results, marking the first time West Nile virus has been found in UK mosquitoes.
West Nile virus is already widespread in parts of Europe, Africa, and the Americas, and its recent spread northwards is likely driven by climate change. In this UK study, over 32,000 mosquitoes have been tested to date, including species such as Culex pipiens and Culex modestus. Despite the detection, UKHSA emphasised that there is no current evidence of sustained circulation in birds or mosquitoes. Only seven travel-associated human cases have been reported in the UK since 2000. Enhanced surveillance and targeted public health messaging have now been initiated to ensure any potential emergence is caught early. Doctors have also been advised to consider testing for the virus in patients with unexplained encephalitis through specialist labs.
While this detection is not unexpected given the virus’s spread across Europe, it reinforces how rising temperatures are enabling mosquito-borne diseases to reach new areas. Ongoing surveillance and local habitat management remain key tools in reducing mosquito numbers and minimising risk. Simple preventive measures, such as wearing protective clothing and using insect repellent, can reduce the chance of bites in affected areas.
Reference
UK Health Security Agency. First detection of West Nile virus in UK mosquitoes. 2025. Available at: https://www.gov.uk/government/news/first-detection-of-west-nile-virus-in-uk-mosquitoes. Last accessed 22 May 2025.
