Tropical Diseases Could Reach UK Due to Climate Change, Scientists Warn

Rising global temperatures are making the UK increasingly susceptible to tropical diseases that were once confined to hotter regions, experts have warned. They are calling on ministers to boost international efforts to curb the spread of these illnesses at their source.

Specialists in mosquito-borne diseases caution that recent UK government cuts to foreign aid could severely undermine critical programmes for disease monitoring, prevention, and treatment in regions where infections such as dengue, Zika, and chikungunya are common. The collapse of these systems may leading to more deaths overseas and elevate the likelihood of such diseases spreading across Europe and into the UK.

The alert comes after the UK Health Security Agency reported the first discovery of West Nile virus in mosquitoes found in the UK. While there is currently no evidence of human transmission and the risk to the public is considered low, scientists remain concerned about the virus’s potential to spread further.

West Nile virus, like dengue and Zika, is carried by mosquitoes and has historically been confined to warm climates. However, global warming has enabled these diseases to move into cooler regions, including parts of northern and western Europe. In 2024 alone, more than 1,400 cases of West Nile virus and several hundred cases of dengue were recorded, mostly in France and Italy.

Dr Robert Jones, assistant professor at the London School of Hygiene and Tropical Medicine, warned that if temperatures rise by 4 to 5°C above pre-industrial levels, Europe could face a fivefold surge in dengue and chikungunya outbreaks by the 2060s.

“We are unlikely to see a dramatic surge in tropical diseases,” said Jones. “However, climate change is making the UK more hospitable to the insects that that transmit some pathogens that cause tropical diseases.”

“Projected increases to UK temperatures in the coming years will increase the risks of West Nile virus outbreaks, potentially with epidemics appearing by the second half of the century.”

For such diseases to take hold in the UK, infected individuals would need to be bitten by the appropriate mosquito species, which could then pass the virus to others.

At present, the UK lacks sufficient numbers of these mosquito types, noted Professor Tom Solomon, director of the NIHR Health Protection Research Unit for Emerging Infections and the Pandemic Institute.

“At the moment, Aedes mosquitoes such as the Asian tiger mosquito are the main vectors of dengue fever and zika, whilst for West Nile, Culex species are important. These mosquitoes have been detected in the UK, but are not yet fully established in sufficient numbers to cause large outbreaks.

“But as the UK gets hotter, local mosquito populations are changing, which, long-term, could result in local transmission of tropical diseases, especially in southern England.”

As things stand, there is no need for mass NHS vaccinations for diseases like yellow fever, or for widespread use of insect repellent during UK summers. However, scientists emphasise that proactive global action is key.

Professor Heather Ferguson of the University of Glasgow, who leads the Mosquito Scotland initiative, stated that the UK’s most effective long-term defence lies in investing in the control of mosquito-borne diseases in the tropical regions where they cause the greatest harm.

She added: “We should never lose sight of the fact that one child under five dies of malaria approximately every minute, with approximately 600,000 deaths and over 100 million cases in 2023 alone.

“As we learned from the pandemic, infectious diseases have no borders and can spread quickly when the conditions are right. The government’s cuts to foreign aid will lead to a collapse in crucial surveillance, control and treatment programmes in endemic countries, causing more deaths from tropical disease.

“The best way to defend ourselves is to not only maintain, but strengthen investment into the global elimination efforts that will ultimately keep all of us safe from tropical disease.”

Solomon said: “Controlling mosquito-borne diseases overseas is also an important element of protecting the UK. If they are controlled overseas, there is less chance of them spreading to the UK.”

“Long-term policies that address net zero challenges globally are arguably the best protection against such diseases,” said Prof James Wood, the infectious disease epidemiologist at the University of Cambridge and the co-director of Cambridge Infectious Diseases.

A FCDO spokesperson said: “Global health security is essential for our national security and the UK is a leading donor in the fight against mosquito-borne tropical diseases. We play a major role in the global malaria response, and we are the third largest donor to the global fund.

“This week we adopted a new pandemic agreement, which will improve the way countries around the world work together to detect and combat global health threats. As the minister for international development, Baroness Chapman, has said, global health will be a priority for the UK’s international development. Diseases cross borders so our diplomacy must too.”

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