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  • Writer's pictureDr Claudine DeMunter

Lyme Disease

Updated: Sep 3, 2020

What is Lyme Disease?

Lyme disease is an infection caused by an infected tick bite and whilst less common in the UK, we have seen an increase in cases. Most people are outdoor workers, particularly forestry workers, but visitors and holidaymakers to countryside areas where ticks are found, may also be at risk.

The first and most common symptom is a rash that spreads out from the site of the tick bite. Left untreated, the germs (bacteria) can spread to other areas of the body. In some cases this can cause serious symptoms - often months after the initial tick bite. A course of antibiotic medication will usually clear the infection.

How do humans get Lyme disease?

The germ (bacterium) that causes Lyme disease lives in mainly rodents such as mice, some birds and some other small animals and is usually harmless to them. Ticks are small insect-like creatures, about the size of a pinhead. Ticks feed by biting the skin and sucking blood from animals and sometimes humans. In this way, some ticks become infected with the germ that causes Lyme disease.

Ticks cannot jump or fly but can climb on to passing humans from long grass or foliage. If an infected tick bites a human, then the germ may be passed into the human. The germ that causes Lyme disease is not passed from person to person.

Good News: Most ticks in the UK are not infected by the germ that causes Lyme disease. Therefore, most tick bites will not cause Lyme disease.

After a person has been bitten by a tick, it usually takes 24-48 hours for the bacteria in the tick to pass into that person. Ticks are tiny and 'cling on' to you once they bite you. Often they will go unnoticed until they then suck blood and become swollen ('engorged') with blood. The germ is normally carried in their gut and only travel up to their mouth and into your skin once they have been fed and are bloated. This normally takes about 24 hours, but can be less. Therefore, if you remove a tick soon after being bitten - within 24 hours - you are much less likely to develop Lyme disease, even if it was an infected tick.

So, it is only certain ticks i.e. those that are infected, that bite and are not noticed clinging on to the skin, which cause Lyme disease. However, ticks are very small, and often do not hurt when they bite so it is quite easy to have a tick bite without noticing. Many people who develop Lyme disease cannot remember being bitten by a tick.

Once bacteria are passed from the infected tick into your skin, they then multiply and travel in the bloodstream to other parts of the body to cause symptoms in the skin, joints, nerves and heart.

What are the early signs?: Generally 3-40 days after the tick is detached and usually within 7-10 days.

  • Rash, known as erythema migrans, occurs in 65-80%, so not all, of cases (as shown in article photo). A solid oval, pink/red/purple bull’s eye lesion (may have central clearing), expands over weeks, average size 5cm, not usually itchy, hot nor painful. It may be distant to the site of tick bite and there may be more than one. Many insect bites cause a small red blotchy 'allergic' rash to appear soon after the skin is bitten and these soon go away. The rash of erythema migrans is different in that it, usually develops several days after the bite, lasts for longer and has a typical spreading circular appearance

  • Lymph nodes may become enlarged

  • Flu-like symptoms occur in 30% of patients giving fever, headache, fatigue, arthralgia

Some cases of Lyme Disease appear weeks or months after at tick bite and this is known as Early Disseminated (widespread) Lyme Disease. When symptoms are displayed some months/years after a tick bite, it is known as Late Onset Lyme Disease. Symptoms are varied and rarely all present together such as multiple rashes, enlarged lymph nodes, joints and muscles inflammation (pain, stiffness, joint swelling), meningitis or rarely encephalitis. Cranial nerve palsy on one or 2 sides with facial nerve palsy being more common (Bell’s palsy), inflammation of peripheral nerves causing pain and weakness. Inflammation of the heart (carditis) that can either cause no symptoms at all or cause syncope (fainting), breathlessness or chest pain. Late Onset Lyme Disease signs and symptoms will tend to be more recurrent or severe in nature.


When the signs appear early, there is no laboratory test that can be done as antibodies only appear within 6 weeks – Children with early disease can be misdiagnosed as having a viral illness, therefore diagnosis at this stage is based on signs and history, exposure or likelihood of a tick bite and treatment started.

If over 6 weeks has passed, a blood test may be performed to check on presence of antibodies and treatment started. All the symptoms can also be due to other illnesses, so the diagnosis of Lyme Disease is based on the likely association with tick bites and on the presence of antibodies in the blood if more than 6 weeks have passed.

Other investigations may need to be done to evaluate the extent of Lyme Disease: For the heart, an ECG and a heart echo are recommended particularly in children with early disseminated Lyme Disease. For neurological signs, a lumbar puncture is required initially. For joint issues, an ultrasound and intra-articular joint fluid aspiration may be indicated.


Specific antibiotics for 3-4 weeks is recommended if patients have symptoms. Usually these are taken orally unless there are serious complications. The earlier these are started, the less likely it is to develop late onset Lyme Disease, the treatment of which is difficult and controversial. If a patient has a suspected tick bite but is otherwise asymptomatic, there is no evidence to support giving preventative antibiotics. Any complication, cardiac, neurological or joint related, also needs to be seen by a relevant specialist. New specific NICE guidelines were issued to healthcare providers in July 19 and are followed for diagnosis and treatment of Lyme Disease.

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