Lyme disease, also known as Lyme borreliosis, is caused by the bacteria Borrelia burgdorferi. The disease was first identified in the 1970s, in the United States (US) following an outbreak among children in Lyme, Connecticut. The infection is found mainly in Europe, North America and in temperate areas of Asia. The risk of infection in humans increases from late spring through the summer months and into autumn. During this time, more individuals engage in outdoor leisure pursuits and activities that take them into areas with a risk of infection.
Lyme disease is transmitted to humans by the bite of an infected tick. Ticks become infected when they feed on small animals that carry the infection e.g. birds, voles, mice and squirrels. Not every tick carries the infection. Infection is transmitted in the saliva of the tick during feeding.
The appearance of a circular rash at the site of a tick bite is the first sign of infection; the rash is called erythema migrans. The rash occurs in around 60-80% of infected individuals and may take between 3-30 days to develop following the tick bite. The rash will continue to increase in size over several days and can extend up to 30 cms in diameter; the rash is usually painless. Other symptoms include fever, headache, chills, fatigue, joint pains, muscle ache and swollen glands.
If the illness is not treated, within a few days to weeks the infection may spread to other areas of the body and affect the heart, nervous system and joints.
Antibiotics will cure most cases of Lyme disease, particularly if treatment is started early. A small number of individuals with Lyme disease however, may continue to experience symptoms for months or years, even after treatment with antibiotics.
Recommendations for Travellers
There is no vaccine available against Lyme disease. The main preventive measure is to avoid being bitten by ticks.
Important points to consider:
- Be aware of the tick risk. Risk areas include woodland, moorland, parkland, heaths and gardens with wildlife. Areas with deer and sheep are risky, as although these animals do not carry Lyme disease, ticks feed on them and they play an important role in the population and transportation of ticks.
- Ticks are more common from April to October.
- Activities such as camping, picnics, hiking and cycling can increase risk.
- Known risk areas include Exmoor, the New Forest, the South Downs, the Lake District, the Yorkshire moors. In Scotland much of Perthshire, Highlands, outer islands and rural areas are known risk areas.
Preventing tick bites and transmission of Lyme disease:
- Ticks adhere to the ends of grasses, vegetation and foliage and are easily transferred to humans as they brush past, sit/lie on the grass etc. Keep to the footpath where possible and do not sit directly on the grass.
- Practice insect bite avoidance: protect the skin; wear long trousers/sleeves and tuck trouser bottoms into socks. Use repellent on any exposed skin, one that contains DEET 30-50%.
- Clothing can be pre-treated with permethrin insecticide for added protection.
- Wear light coloured clothing as it is easier to see the ticks against a light background.
- At various times, especially at the end of the day, examine the skin for ticks. Ticks are about the size of a pin head before they feed so may easily be missed.
- When checking for ticks it is important to inspect warm, moist areas like the skin folds behind the knees, elbows and groin area. Check each others back and examine the neck, head and scalp of children carefully.
- It is important to remove the tick early as it does not feed immediately and transmission of infection may be avoided if it is removed as soon as possible.
- Do not cover the tick in any substance before removing e.g. petroleum jelly, oil or lotion and do not attempt to burn the tick.
- Ticks can be removed with tweezers or a proprietary remover (available from vets or pharmacies). Grasp the head of the tick as close to the skin as possible and pull steadily in a vertical direction; try not to squeeze the body of the tick as this may transmit infection.
- Make sure that ticks are not carried home on clothing, children or the family pet dog.
- If you develop a rash around the tick bite or feel unwell, consult your doctor and tell them that you have been bitten by a tick.
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