Lyme disease is caused by infection with Borrelia burgdorferi and is transmitted
to humans through the bite of an infected tick. Infection is acquired by immature
ticks from infected small wild mammals, which act as a reservoir of the organism.
Prolonged feeding (>24 hours) of infected ticks on a human can result in disease.
Geographical distribution of the disease in Europe closely follows that of the known
range of the tick vectors and ramblers and campers are at increased risk of disease
due to their greater exposure to the disease vectors. The true incidence of the
disease is unknown due to incomplete detection and reporting of cases, but is estimated
to be 0.3 per 100,000 in the UK.
Main clinical features
These follow a tick bite (although this may go unnoticed). A rash develops which
usually has the appearance of a reddened circle that expands away from the bite
and clears in the centre. The skin may be warm but is not usually painful. Early
localised disease may be associated with “flu-like” symptoms of malaise,
fatigue, lethargy, headache and joint and muscle aches. Other, more severe, manifestations
of the disease include arthritis of large joints, meningitis and myocarditis, all
of which may occur without the rash.
Transmission of B. burgdorferi does not take place until the tick has been
in place for > 24 hours. The skin syndrome usually occurs within 1 month of the
tick bite. Other manifestations may take several weeks or months to develop.
Voluntary laboratory reports.
Tick and tick Borne Disease Factsheet
Annual Surveillance Tables