Lyme borreliosis: a tick-borne spirochaetal disease

The spirochaete Borrelia burgdorferi (sensu lato) is the cause of Lyme borreliosis, a common tick-borne disease with a wide geographical distribution. B. burgdorferi s.l. was first isolated in 1982 after a clinical and epidemiological study of an unusual outbreak of arthritis in children in the town of Old Lyme, Connecticut, USA. Despite this recent discovery, there is evidence that Lyme borreliosis has existed for many years. Clinical manifestations are diverse, but antibiotic therapy is largely successful when initiated early in the disease. Molecular-based studies have improved the laboratory diagnosis of Lyme borreliosis and played a significant role in ecological and taxonomic investigations of the pathogen. B. burgdorferi s.l. is now divided into some nine genospecies and genomic groups, some of which have been associated with particular manifestations of disease, while the number of tick species found to be competent vectors has also increased. The emerging ecology of B. burgdorferi s.l. is more complex than originally described and, consequently, the assessment of risk of disease to an individual bitten by a tick should include establishing the identity of the tick, duration of attachment and degree of engorgement, as well as consideration of the individual's way of life and environment. (C) 1998 Chapman & Hall.