What is Lyme disease?
Lyme disease is a bacterial infection that is spread to humans by infected ticks. Ticks are tiny arachnids and commonly found in heath and woodland areas. Ticks feed on the blood of mammals including humans.
What causes Lyme disease?
- Lyme disease is caused by a group of closely-related spirochaetal bacteria species, together known as Borrelia Burgdorferi sensu lato. These bacteria are carried in the blood of various birds (such as pheasant and blackbirds) and mammals (such as mice, voles, squirrels and foxes).
- If a tick bites an animal that has the bacteria, then the tick will also become infected. If an infected tick bites a human, then the infection can be passed on to the human as the tick feeds on their blood.
- Ticks are small and their bite painless so may go unnoticed.
- Tick saliva has several functions. It helps to numb the bite area so that the host can’t feel it feeding, and to prevent inflammation and keep the blood flowing. Saliva is introduced continuously during the feeding process. Borrelia bacteria are transmitted along with the tick’s saliva. The longer the tick remains attached, the more likely it is for a person to become infected. Due to the small size of ticks and the anaesthetic properties of their saliva, not all people with Lyme disease remember being bitten.
- The bacteria move through the skin, into the bloodstream and the lymphatic system (the system which drains and filters our blood to help fight infection).
- The bacteria that cause Lyme disease can damage joints and the nervous system including the facial nerve.
- If the facial nerve is damaged, then the infected person may experience weakness or paralysis of the facial muscles, usually on one side of the face. The medical term for this is ‘facial palsy’.
- Symptoms will reveal themselves in the mid- to late stage of the disease.
What are the symptoms of Lyme disease?
- Approximately three to thirty days after the person has been bitten by an infected tick, the bacteria disseminate from the bite site into the surrounding skin tissue. This may result in an expanding pink or red rash surrounding the bite area. A Lyme disease rash is usually greater than five centimetres in diameter and may be circular, oval or irregular shaped. It may be solid in colour or like a bull’s-eye on a dartboard. The rash expands over a period of days to weeks and, in some cases, can reach up to seventy five centimetres in diameter. The rash may not be observed if it appears under body hair, under hair on the scalp or in another inaccessible place. Darker skin may make it difficult to identify a rash and paler rashes can be overlooked even on lighter skin. Even without treatment a Lyme disease rash will resolve but a lack of treatment can allow the disease to progress to more serious and debilitating symptoms.
- You may develop flu-like symptoms, joint pain or tiredness.
If left untreated, then several months or years later you may experience the following:
- Muscle pain.
- Joint pain and swelling of the joints.
- Neurological symptoms, such as a temporary paralysis of one side of your face.
- It may also trigger symptoms, such as chronic fatigue syndrome or fibromyalgia. This is known as chronic Lyme disease, but further research into this area is required.
Is Lyme disease contagious?
No. A person with Lyme disease cannot pass it on to others. The disease can only be passed on by an infected tick.
How is Lyme disease diagnosed?
Early stage diagnosis
- Early diagnosis is difficult unless the person goes to their GP when the rash is present. This is because symptoms of Lyme disease are similar to many other conditions. However a GP who takes a careful history and identifies possible risk factors may be successful in making an accurate diagnosis in the acute (early) stage of the infection.
- Blood tests can be useful in the acute stage of the infection but may not always confirm a diagnosis.
- The tests need to be carried out at least a few weeks after you are bitten by the tick because it can take this long for the infection to develop. You may need to be re-tested if Lyme disease is still suspected after a negative test result.
Later stage diagnosis
- Diagnosis in the later stages of the disease is particularly difficult. However if you develop flu-like symptoms followed by joint pain, arthritis, headache or depression, your GP may then ask if you have been visiting woodlands or heath lands where ticks are known to exist.
Who is at risk of developing Lyme disease?
- Forestry workers
- Those who participate in woodland and heathland sports, or whose work brings them into close contact with infected animals.
It’s important to note that you don’t necessarily need to have been in a high risk area to be bitten by a tick.
Are there any other risk factors?
- Most tick bites occur in late spring, summer and early autumn, as this is the time most people are out of doors or participating in activities which bring them into close contact with ticks.
- Parts of the UK that are known to have a high population of ticks include:
- The New Forest in Hampshire
- The South Downs
- Parts of Wiltshire and Berkshire
- Thetford Forest in Norfolk
- The Lake District
- The Yorkshire Moors
- The Scottish Highlands
What is the treatment for Lyme disease?
Once Lyme disease has been diagnosed, you will be treated with antibiotics. The antibiotics prescribed will depend on the stage of your Lyme disease. Normally they are taken for two to four weeks but some people may need to take them for longer.
What can I do to prevent getting Lyme disease?
- There is no vaccine at present.
- Avoid being bitten when in wooded or heath areas known to have a high tick population. This can be done by following the precautions below:
- Wear a long-sleeved shirt.
- Tuck your trousers into your socks.
- Use insect repellent.
- Check yourself for ticks.
- Check your children and pets for ticks.
The NICE guideline committee 2018 made a recommendation for further research on the incidence, presenting features, management and outcome of Lyme disease, including in women with Lyme disease who are pregnant. The guideline committee recommended that babies born to mothers who have been treated for symptomatic Lyme disease during pregnancy be clinically assessed and discussed with a paediatric infectious diseases specialist.
Last reviewed: 28-03-2019 || Next review due: 28-03-2021