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Press Release - 20 July 2006
Lyme borreliosis warning for Bath’s woodland walkers
Walkers in the woodlands around Bath have been advised to check for bloodsucking ticks when they get home.
This follows the discovery by scientists from the University of Bath that a significant number of the ticks found in the Bath area are infected with the bacterium that causes Lyme borreliosis.
Lyme borreliosis is a major health problem in north-east America and mainland Europe, but despite affecting an estimated 1,000-2,000 people in the UK each year, it is still relatively unknown here.
The disease is caused by three species of bacteria, Borrelia burgdorferi, Borrelia afzelii and Borrelia garinii, which are spread by infected ticks when they feed on blood.
Half of the people infected with Lyme borreliosis initially develop a reddish skin rash in a ring shape, and this may be the only sign of infection. The rash spreads out from the site of a bite after three to 30 days. Without antibiotic treatment, Lyme borreliosis may become chronic.
In Europe, chronic Lyme borreliosis is characterised by neurological symptoms, involving paralyses and numbness of the extremities, as well as dermatological disorders, such as acrodermatitis. These symptoms may appear years after an infectious tick bite.
In north-east America, arthritis is the most frequent symptom. There is no vaccine against Lyme borreliosis available.
The disease is called after the town Old Lyme in Connecticut, USA, where it was first described three decades ago.
As part of a final year student project, scientists from the University discovered that as many as 5-10 per cent of the ticks from the woodlands around Bath were carrying the infectious bacteria.
“It is likely that over the last few decades there has been an explosion in the number of ticks living in the woodlands around Bath and south-west England,” said Dr Klaus Kurtenbach, a microbiologist in the Department of Biology & Biochemistry who led the study.
“This is most probably due to the growth in the local population of roe deer, one of the tick’s preferred hosts.
“The bacterium does not survive in deer, so its presence amongst the tick population in southern England is probably caused by birds which have brought the infection from other parts of Europe. This notion is supported by genetic analyses of the bacteria found around Bath.
“People should continue to enjoy their walks through the woodlands around Bath, but as with walkers in other European countries they should also be aware of the risk of contracting Lyme borreliosis; they should stick to footpaths and should remove a tick with tweezers if they find one on their body.
“The risk of acquiring an infection from an infected tick is very low in the first 48 hours that it is attached, so early removal of the tick is an effective prevention of infection.”
The tick most commonly found in British woodlands, Ixodes ricinus, is a tiny spider-like creature about the size of a poppy seed. It has three stages of development: larva, nymph and adult.
In order to progress to the next stage of development the tick needs to take a blood meal. It usually feeds on blood from animals, including ground-feeding birds, but it occasionally bites humans.
Ticks prefer woodlands and are rare in open grassland. Host-seeking ticks do not actively hunt or attack their hosts; they wait in the leaf litter or foliage close to the ground for an animal to pass by.
Once a tick has encountered a host, the parasite crawls over the host until it finds a suitable site to start its blood meal. Each blood meal usually takes between three to five days to complete.
It is mainly the small nymphal stage that feeds on humans and transmits the infection rather than the large adult stage of the tick which people may know from their dogs.
In southern England all tick stages are active from early spring through to late autumn.
The researchers advise anyone who is concerned about Lyme borreliosis to speak to their GP.
The research was carried out by student Ruth Mitchell and supervised by Dr Kurtenbach and his postdoctoral research assistant Dr Gabriele Margos.
Ruth won the University’s Richard Codner memorial prize based on her outstanding final year project report which is soon to be published.
She has been awarded a special grant by the Biotechnology and Biological Sciences Research Council to continue her work in the laboratory.
Dr Kurtenbach has recently moved to the University of Bath from Yale University and is funded by the Wellcome Trust and the National Institutes of Health (USA).
He is lead author of a paper on the fundamental processes in the evolutionary ecology of vector-borne zoonoses, including Lyme borreliosis, that will be published in Nature Reviews Microbiology shortly.
The researchers will be monitoring the local environment for changes in the tick populations and their infections in the coming years.
The University of Bath is one of the UK's leading universities, with an international reputation for quality research and teaching. In 16 subject areas the University of Bath is rated in the top ten in the country. View a full list of the University's press releases: http://www.bath.ac.uk/news/releasesTop