Londoners are just as likely to pick up a tick in the city this summer as they are in Wales, according to researchers from the Big Tick Project at the University of Bristol.
“The prevalence of Lyme disease in London has increased in recent years,” said Dr Oliver Barnett, a specialist in chronic diseases at the London Clinic of Nutrition. “Richmond, especially, is a hotbed,” he said.
There is no concrete link between the observed increase in Lyme disease and the number of ticks in London – but the circumstantial and anecdotal evidence is convincing, according to Barnett.
“The tick population in the UK definitely seems to be increasing,” said Julia Knight of Lyme Disease UK, a charity dedicated to raising awareness of the tick-borne disease.
“An early, warm spring, like the one we’ve had this year, means the number of ticks increases,” she said. “Ticks become active when the temperature reaches 8C and don’t become dormant again until about a week of temperatures under 8C.”
More days per year now surpass 8C than at any other point in the previous 40 years, according to data from the UK’s Climate Impacts Programme.
The Western Highlands, southwest England (including Dorset, Somerset, Cornwall, and Devon), Norfolk and Suffolk have the highest density of ticks, according to the Big Tick Project.
Professor Richard Wall, who studies ticks and tick-borne diseases at the University of Bristol, said there is evidence showing that people have been seeing more ticks than in past years.
“There is one published paper, which suggests that there may have been an increase over the past 20 to 30 years,” he said. “What this paper shows is anecdotal evidence of the increase of ticks. Researchers went out and asked farmers if they had noticed an increase and [they] were aware of more ticks.”
Sheep are one of adult ticks’ favourite hosts, making the parasites more noticeable to farmers on a daily basis.
The 2008 report authored by the Oxford Tick Research Group, part of the University of Oxford’s Department of Zoology, revealed that 73 per cent of survey participants had noticed an increase in the small arachnids.
Retired professor Sarah Randolph led the Oxford Tick Research Group and said that despite the increase in tick sightings by farmers, there is no concrete data demonstrating an increase in the UK’s population of ticks.
“The problem with perceived trends in these matters is that there is no reliable data,” she said. “It would require several decades of systematic surveying which does not exist and is not something that would attract the necessary funding to make a start now.”
However, Randolph acknowledges that even without verification, there does appear to be an increase in the tick population based on findings from the survey.
“While deer populations continue to increase without control, tick populations are very likely to increase,” she said.
According to the Deer Initiative, an organisation monitoring the UK’s deer population, numbers in London are increasing and the deer population in Britain is now at its highest level for more than 1,000 years.
Deer are the “most important” tick hosts nationwide, according to Wall. Adult ticks feed on deer and use the energy that they gain from feeding to reproduce.
The report said that increases in tick sightings coincided with areas where deer populations had also noticeably increased.