General Information on Lyme borreliosis

(See also FAQ and Diagnosis pages)

Background

Lyme borreliosis is an infection caused by spiral-shaped bacteria called Borrelia burgdorferi, which are carried by some types of ticks. These hard-bodied Ixodid ticks (sometimes known as sheep, deer, or woodland ticks) may be found in forested, heathland and moorland areas and also in suburban parklands; they are less frequently found in coniferous forests. Areas inhabited by deer are particularly suitable habitats for ticks, but not every tick infested area has a high risk of Lyme borreliosis, and most ticks do not carry the bacteria.

Transmission from ticks

Infected ticks can transmit the organisms during blood feeds, when they may be attached to the skin for several days if left undisturbed. Late spring, early summer and autumn are peak times for tick feeding, and ticks tend to be found seeking feeds in areas of long grass.  A lower level of tick feeding activity can take place at other times of the year, even on mild winter days.Ticks need a blood meal before they can metamorphose into the next stage of their 3-stage life cycle (larva, nymph and adult), or lay eggs. They are very small (about the size of a poppy seed), and can easily be overlooked, so it is important to be aware of the risk of tick bite, check for attached ticks and remove them promptly.

Symptoms

The most common problem associated with the infection is a rash spreading from the site of a tick bite, but more serious problems can occur. These include a viral-like meningitis, facial palsy, other nerve damage or arthritis. All stages of the infection respond to treatment with antibiotics, but it is easiest to treat at an early stage, especially when the rash is present.

Occurrence

(See also Epidemiology pages)

Areas in the UK where people acquire Lyme borreliosis include many popular holiday and outdoor activity destinations such as the New Forest, Exmoor, other woodland or heathland areas of southern England, the Lake District, the Scottish Highlands and Islands, North York moors, Thetford Forest, and the South Downs.  Although these are high risk areas for Lyme borreliosis, any area where Ixodid ticks are present should be regarded as a potential risk area. At least 50% of infections acquired in the UK are known to have occurred in southern counties of England.

At least 15-20% of laboratory-confirmed infections are acquired abroad, mostly by holidaymakers, although recently a significant number of cases have been identified in people from eastern and central Europe and the Baltic Republics. European countries include France, Germany, Austria, Sweden, Norway, Denmark, Czech Republic, Slovakia, Slovenia, Croatia, Romania, Bulgaria and the Baltic Republics. The north-eastern and upper mid-west states of the USA have numerous high risk areas. Each year, a significant number of infections are acquired in the course of activity holidays, including walking, trekking and mountain-biking.
 

Prevention

No vaccine against Lyme borreliosis is currently available, so tick awareness, avoidance of tick infested areas if possible, avoidance of long grass, use of appropriate clothing in tick infested areas, and early removal of attached ticks remain the most important prevention measures. Insect repellents containing DEET are also useful to protect uncovered areas of skin.

Infection can be prevented altogether by taking measures to avoid tick bites and by removing ticks at an early stage of their blood feed, as a tick usually has to be attached to the skin for at least 24 hours before transmission can take place. Removal is best achieved with fine-toothed tweezers, pulling steadily away from the skin. Inexpensive proprietary tick removal implements are available from some veterinary surgeries and pet supply stores, and are useful for people who are likely to have frequent exposure to ticks.

Attached ticks should not be covered with volatile oils, or burnt with lighted cigarette ends or match heads, as these actions risk damaging the skin.

Further information on tick removal can be found here

and on the CDC website: http://www.cdc.gov/lyme/removal/index.html

It is important to check the skin surface for attached ticks, including skin folds (armpits, groins, under the breasts, backs of knees and around the waistband) after a day out in a tick infested area. Carefully check the head and neck, including the hair, of young children. Also check that unfed ticks are not brought home on clothes, and make sure that pets do not carry ticks home on their fur.

Last reviewed: 23 March 2012