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An adult female sheep tick, a tick vector of Lyme borreliosis in Europe
An adult female sheep tick, a tick vector of Lyme borreliosis in Europe
Dr Klaus Kurtenbach (far left), Dr Gabriele Margos (far right), and the research team at Bath
Dr Klaus Kurtenbach (far left), Dr Gabriele Margos (far right), and the research team at Bath

Press Release - 24 June 2008

New research reveals the true origins of Lyme disease and predicts how it will spread

The bacterium that causes Lyme disease, the fastest growing vector-borne disease in North America, originated in Europe before the Ice Age, says new research by academics at the University of Bath.

Previously believed to have come from America, the discovery of its true origins will enable researchers to predict how it will continue to evolve, and to prevent its spread.

The tick-transmitted bacterium, Borrelia burgdorferi, was discovered in Old Lyme, Connecticut, in the 1970s. It occurs in North America, Asia and Europe, although it is currently relatively unknown in the UK.

Despite three decades of research there is no available vaccine, and, if left untreated, the disease can cause arthritis and paralyses.

The discovery of the true origins of the bacterium was made using a novel molecular technique developed by academics in the University’s Department of Biology & Biochemistry.

The technique analyses genes of the bacteria which contain information on how the bacteria evolved, on how and where they emerged and how they are spreading. It analyses the DNA of the bacterium and constructs a ‘family tree’ based on the molecular information. It is the first time this technology has been tailored for tick-borne diseases.

Dr Klaus Kurtenbach, who is leading the project, said: “We know that Lyme disease cases are continuously rising in the US, and the numbers of new cases in the UK appear to increase as well. By understanding their past, we can predict how they are likely to evolve and spread and hopefully stop them in their tracks.”

The researchers studied the evolutionary history of the bacteria by examining the sequences of eight ‘housekeeping’ genes, which evolve very slowly. Such genes are essential for the survival of the bacteria and contain information that is very old.

They analysed 64 different samples of bacterial DNA taken from infected human patients and ticks in Europe and America and identified 33 distinct combinations of the eight genes.

The European and North American sets differed significantly. Computer-generated evolutionary ‘trees’ placed certain European strains closest to a common ancestor and other European Borrelia species, showing Europe as the source.

The ‘tree’ suggested that the bacterium predates the arrival of the first humans in North America, and has only begun to re-emerge over the last few decades as the geographic territory of its tick has been expanding as more land is covered by woodland. It is now the most common vector-borne disease in North America.

Ticks are found in woodlands where small mammals or birds can act as intermediary hosts to infected ticks. People are normally unaware they have been bitten and it can take several weeks after an infectious tick bite for the ring-shaped skin rash to emerge.

At this early stage, the disease can easily be cured by antibiotics. If untreated, it may progress to more serious and persisting symptoms, such as arthritis or paralyses, often affecting facial muscles.

In Europe, chronic Lyme disease 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 infection tick bite.

The research by Dr Kurtenbach, recently published by the Proceedings of the National Academy of Sciences of the United States of America (PNAS), is the outcome of a transatlantic collaboration between the Universities of Bath, Oxford, Yale and Imperial College London; the Centre for Disease Control; and the New York Medical College.

Dr Kurtenbach's research is funded by the Wellcome Trust; the Biotechnology and Biological Sciences Research Council; and the National Institutes of Health, United States.


The University of Bath is one of the UK's leading universities, with an international reputation for quality research and teaching. View a full list of the University's press releases: http://www.bath.ac.uk/news/

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