Clinical Notes : Infection and Sepsis

190. Lyme Disease

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Lyme disease is an infection caused by a number of bacteria belonging to the Borrelia genus, including Borrelia burgdorferi. 

Borrelia are spirochetes, and have many similarities to the syphilis organism.


Lyme disease is transferred to humans by the bite of an infected tick (not all ticks carry Lyme disease).

There is a wide variation in prevalence of bacteria within tick populations.


Ticks are found in grassy/wooded areas.

Patient groups who may be especially at risk are those who take part in outdoor pursuits, such as gardening, walking, running, or camping.

Urban parks can also have a high level of ticks. Occupational groups may also be affected, such as farmers or forestry workers.


Lyme disease can be a multisystem infection.


It has been considered hard to diagnose, with many patients believing they have had untreated Lyme disease for years because laboratory tests only identify antibody response, not an active infection.

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Ticks in Ireland


The incidence of Lyme disease is on the rise.

Lyme disease is a notifiable disease in Ireland, but only for stage 3 neuroborreliosis cases (who have positive 2 tier tests). Getting a positive test can be a challenge and therefore under reporting occurs.

Studies in the 90s cited Counties Kerry, Wicklow & Galway as particular hotspots.

The most common area for ticks was21% in Galway, 16% in Cork & 14% in Kerry.

A study in 2010 identified Connemara as being endemic for Lyme disease (151 cases per 100,000over a 5 year period).

If we look at yearly averages in this study, cases ranged from 2 per 100,000in the West of Ireland, with some parts of Connemara reaching 181 cases per 100,000).

In comparison the Highlands of Scotland [an endemic region] have an average of 81/100,000 in peak season.


A study in Killarney National Park, Co. Kerry cited tick infection rates between 11-29% (close to a thirdof ticks may be infected with borrelia (Lyme disease causing bacteria) in certain areas).


From a study in 1999-2004 by University Hospital Galway, recent travel outside Ireland was documented in only 7 cases (therefore three quarters of patientsmay have been infected in Ireland).

While twenty-two patients (71%) in the above study had a rash at presentation, only 43% of patients presented with an Erythema Migrans rash (a rash may not always be in rings)


In a surveyby Tick Talk Ireland, when asked which country the tick-borne infection took place, 61% of the respondents were infected in Ireland and 22% in NorthAmerica. 17% listed Europe as the source of infection.


47% of ticks were reported to be found in tall grasses (whilst playing, walking camping etc.) and an alarming 22% were found in private gardens.

Ticks can be infected by mice, birds, hedgehogs, farm animals & deer therefore the potential for exposure is high among rural areas in Ireland.


Avoiding tick bites




Early on in the disease process it may just present with a simple skin rash.

About one-third of patients in the UK do not present with a rash.


The most common presentation of Lyme disease is an erythema migrans. The rash is pathognomonic and therefore no other tests are needed.

The erythema migrans rash is different from the inflammatory reaction that can occur with any insect (which tends to come up within the first 24 hours, be intensely itchy and hot, and may subside relatively quickly) and presents as a rash that is:

  • red, increases in size, and may sometimes have a central clearing; however, it may not always have the classic ‘bulls eye’ appearance

  • not usually itchy, hot, or painful

  • usually visible from 1–4 weeks (but can appear from 3 days to 3 months) after a tick bite and lasts for several weeks

  • usually at the site of a tick bite—there may be multiple rashes.

If the classic initial skin presentation of erythema migrans is missed, or is not, then diagnostic uncertainties can arise as many of the other symptoms of Lyme disease have a huge overlap with other diseases.


Lyme disease should be considered in people presenting with symptoms and signs relating to one or more organ systems (focal symptoms) because Lyme disease is a possible but uncommon cause of:

  • neurological symptoms:

    • facial palsy or other unexplained cranial nerve palsies

    • meningitis

    • mononeuritis multiplex or other unexplained radiculopathy

    • (rarely) encephalitis, neuropsychiatric presentations, or unexplained white matter changes on brain imaging

  • inflammatory arthritis affecting one or more joints that may be fluctuating and migratory

  • cardiac problems (e.g. heart block or pericarditis)

  • eye symptoms (e.g. uveitis or keratitis)

  • other skin rashes, including acrodermatitis chronica atrophicans or lymphocytoma


Consider the possibility of Lyme disease in people presenting with several of the following symptoms, because Lyme disease is a possible but uncommon cause of:

  • fever and sweats

  • swollen glands

  • malaise

  • fatigue

  • neck pain or stiffness

  • migratory joint or muscle aches and pain

  • cognitive impairment, such as memory problems and difficulty concentrating (sometimes described as ‘brain fog’)

  • headache

  • paraesthesia.

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Lyme disease is essentially a clinical diagnosis, but serological tests can be used to detect antibodies to the Borrelia bacteria, which may act as confirmation.


Tests for Lyme disease are not 100% sensitive or specific and should only be performed to support clinical observations.

Antibody tests may be performed too early when a response will not yet be positive, so these may need to be repeated 4–6 weeks later.

Test results may also be falsely negative if there is a reduced immune response—e.g. if the patient is taking immunosuppressant medication.


There is no test for active infection or test of cure.


Do not make a diagnosis of Lyme disease with a positive test result but no clinical symptoms.


Lyme disease laboratory investigations and diagnosis

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Removing a tick

It is important that ticks are removed promptly and correctly.

It is best to remove a tick while it is still alive, with a specialised tick remover or fine-tipped tweezers.

It is important not to kill the tick when it is attached as this can increase the risk of transmission.

It is wise to clean the area with antiseptic or soap and water and to keep an eye on it for any subsequent skin changes.

Many tick bites are unnoticed as they tend to be painless and are often found in the hairline, groin, or axillae.


Removing a tick


There is no evidence to support the use of prophylactic treatment following a tick bite.



Treatment and referral


If Lyme disease is suspected, GPs should refer all children under the age of 12 years unless they are being treated for a single erythema migrans lesion and have no other symptoms.


It is also advisable to seek secondary care advice for patients who have had two separate courses of antibiotics and are still symptomatic, and for those whose clinical picture fits the diagnosis of Lyme disease but who test negative.


It is sensible to review the diagnosis of Lyme disease in patients who do not seem to be responding to treatment.


A 3–4-week course of antibiotics at high dose is needed to treat the infection adequately:

A second course of antibiotics may be tried if there is no response to the first course


Some symptoms—especially neurological symptoms—may persist after successful treatment due to damage caused by the organism.


Lyme disease : Prescribing

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GPs can assure patients with a confirmed microbiological diagnosis of neurological symptoms of Lyme disease that this will have no effect on their survival, wellbeing, or social parameters 10 years after diagnosis compared with a control population.

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Lyme disease

DermNetNZ  (CCPL)


Lyme disease : when to suspect and how to manage

Rayment C.

Guidelines in practice

July 2018


Common animal associated infections quarterly report (England and Wales): fourth quarter 2017

Public Health England.

PHE, 2018.



Good outlook for patients with confirmed Lyme neuroborreliosis.

Faust S, Barton S, Rayment C, O’Flynn N.

BMJ 2018; 361: k2284.


The clinical assessment, treatment, and prevention of Lyme disease, human granulocytic anaplasmosis, and babesiosis: clinical practice guidelines by the Infectious Diseases Society of America.

Wormser G, Dattwyler R, Shapiro E et al.

Clin Infect Dis 2006; 43 (9): 1089–1134.


Evidence assessments and guideline recommendations in Lyme disease: the clinical management of known tick bites, erythema migrans rashes and persistent disease.

Cameron D, Johnson L, Maloney E.

Expert Rev Anti Infect Ther 2014; 12 (9): 1103–1135.



Lyme disease.

NICE Guideline 95.

Published date: April 2018

Last updated: October 2018


Lyme disease: guidance, data and analysis—the characteristics, diagnosis, management, surveillance and epidemiology of Lyme disease or Lyme borreliosis.

Public Health England.

PHE, 2015. 



Lyme disease: summary of NICE guidance.

Cruickshank M, O’Flynn N, Faust S on behalf of the Guideline Committee.

BMJ 2018; 361: k1261.


Long term survival, health, social functioning, and education in patients with European Lyme neuroborelliosis: nationwide population based cohort study.

Obel N, Dessau R, Krogfelt K et al.

BMJ 2018; 361: k1998


Lyme disease.

BMJ Best Practice

Last reviewed:September 2019

Last updated:November  2018


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