Mosquitoes carrying deadly diseases including dengue fever and West Nile virus could become widespread across Britain within decades due to climate change, health experts said on Monday.
Warmer temperatures and increasing rainfall could provide ideal conditions for the Asian tiger mosquito, which spreads the viruses causing dengue and chikungunya, to breed and expand into Britain, said a study in the Lancet Infectious Diseases journal.
Vector-borne diseases which are transmitted by insects such as mosquitoes and ticks, are on the rise and have spread across new parts of Europe, including Greece, Italy and France, over the past decade, the study said.
"Lessons from the outbreaks of West Nile virus in North America and chikungunya in the Caribbean emphasize the need to assess future vector-borne disease risks and prepare contingencies for future outbreaks," said Steve Leach from the emergency response department at Public Health England, a government body responsible for improving health and wellbeing.
An outbreak of chikungunya in the Caribbean was first identified in December 2013. By January this year the number had soared from two cases to more than 1.13 million in the Caribbean, Latin America and the United States.
Globally, there are an estimated 390 million dengue infections per year.
As with dengue fever and chikungunya, there is no vaccine for West Nile which infected 9,862 people and caused 264 deaths in the United States in 2003.
The climate in Britain, which is home to 34 different species of mosquito, is already suitable for the transmission of West Nile virus, but there have been no human cases so far, the study said.
A rise in temperature of just two degrees Celsius (3.6 Fahrenheit) could extend the mosquito season by a month and expand areas of Britain suitable for the insects by almost a third by 2030, experts said.
Climate change models predict suitable temperatures for one month of chikungunya virus transmission in London by 2041, and up to three months in southeast England by 2071.
Several species of mosquitoes originating from Asia have been imported into Britain through the global trade in used tires, which are often transported large distances along motorways, moving the eggs to new habitats, the study found.
While no non native mosquitoes have been detected in Britain so far, a better system to monitor imported used tires should be considered, said Jolyon Medlock, joint author of the report and head of medical entomology at Public Health England.
The government body has been conducting surveillance at seaports, airports and some motorway service stations, he said.
Climate change is just one of many factors, including urbanization, land-use change, migration and globalization, driving the increase in vector-borne diseases in Britain, according to the study.