Climate change could make the UK vulnerable to insect-transmitted tropical diseases previously confined to hot countries, scientists have warned. They urged ministers to strengthen efforts to contain their spread abroad, warning that cuts to international aid would lead to a collapse in crucial surveillance and control programmes in endemic countries.
This week, the UK Health Security Agency announced the discovery of West Nile virus in UK mosquitoes for the first time, though it found no evidence of transmission to humans and said the risk to the public was low. West Nile virus, like dengue, chikungunya and Zika, used to be limited to hotter regions, but global heating has expanded its range into cooler areas, including parts of northern and western Europe. In 2024, there were over 1,400 locally acquired West Nile virus cases and several hundred dengue cases, mostly in France and Italy.
Dr Robert Jones, assistant professor at the London School of Hygiene and Tropical Medicine, said that in extreme scenarios with temperature rises of 4–5°C, Europe could see a fivefold increase in dengue and chikungunya outbreaks by the 2060s. “Climate change is making the UK more hospitable to the insects that transmit some pathogens that cause tropical diseases,” he said, adding that projected temperature increases could lead to West Nile virus epidemics by the second half of the century.
For tropical diseases to become established in the UK, infected individuals would need to be bitten by appropriate mosquitoes, which then pass the virus to others. Currently, the UK lacks sufficient numbers of the right mosquitoes, said Prof Tom Solomon, director of the National Institute for Health and Care Research’s health protection research unit. Aedes mosquitoes, such as the Asian tiger mosquito, are main vectors for dengue and Zika, while Culex species carry West Nile. These mosquitoes have been detected in the UK but are not yet fully established. “As the UK gets hotter, local mosquito populations are changing, which long-term could result in local transmission, especially in southern England,” he said.
Scientists stress that the best defence is to tackle these diseases internationally. Prof Heather Ferguson of the University of Glasgow said the government’s cuts to foreign aid would lead to a collapse in surveillance and treatment programmes in endemic countries, causing more deaths. “The best way to defend ourselves is to strengthen investment into global elimination efforts,” she said. Prof Solomon added: “Controlling mosquito-borne diseases overseas is also an important element of protecting the UK.”
