Diagnosis is the process of determining the nature and cause of disease or injury through the evaluation of patient history, examination, further investigative tests and review of laboratory data.
Lyme disease should be a clinical diagnosis based on:
- History of tick exposure, tick bite and any risk factors, eg outdoor leisure activities or occupation, which increase the likelihood of contact with ticks.
- Clinical symptoms and how these developed.
- Any evidence of an erythema migrans rash.
- Physical signs on examination eg facial palsy, radiculitis, meningoencephalitis.
- Diagnostic tests.
- Treatment received- especially prior antibiotic or immunosuppressant treatment which may affect Lyme serology test results.
How is Lyme Disease Diagnosed?
Because there is no definitive test for disease activity, and no test that can rule out Lyme disease, LDA believes that clinical judgement is vital when assessing patients and interpreting the results of any tests. It is important to recognise typical symptoms and signs, though these may overlap with many other conditions, which complicates diagnosis.
Information from official sources is included here so a patient may share these with their doctor who may not have come across Lyme disease before.
Clinical case definitions for Europe  describe and illustrate how Lyme disease may typically affect the skin, nervous system, joints, heart and eyes.
“For a diagnosis of Lyme borreliosis to be considered, the patient must have been exposed to the risk of tick bite. A history of documented tick bite is not essential because many tick bites go unnoticed.”
“Lyme borreliosis is very similar in Europe and North America but the greater variety of genospecies in Europe leads to some important differences in clinical presentation.”
Although European Lyme disease is known to cause more neurological symptoms and less arthritis compared with North American Lyme disease, there have been few studies on the range of symptoms. A 2006 European paper  concluded:
See here for a list of symptoms and signs that have been associated with Lyme disease.
Lyme disease with a rash
In approximately two thirds of UK cases, the patient notices a rash. The erythema migrans rash, as it is called, appears on average 11-18 days after the tick has detached or was removed (range 1-129 days). The rash may be mildly painful or itchy but is often not. It may remain for several months.
The NICE CKS website (Clinical Knowledge Summaries)  states:
“Make a clinical diagnosis of early Lyme disease in people with erythema migrans and a history of a recent tick bite or possible exposure to ticks (recreation, residence, or work in a forested, heathland, or moorland area, or even in suburban parkland).”
“Testing is not generally considered to be necessary for people with erythema migrans and a history of a tick bite or possible exposure to ticks, as this presentation is sufficient to make a clinical diagnosis of Lyme disease.”
As all sources emphasise that early treatment is more likely to be successful, anyone presenting with an erythema migrans rash should receive treatment without waiting for a blood test. Without appropriate treatment Lyme disease may spread to other sites as described below.
Lyme disease: other symptoms and signs
CKS  gives the following guidance:
Flu-like symptoms – these may include fever, headache, tiredness, nausea, vomiting, arthralgia (joint pain), and myalgia (muscle pain); there are no significant respiratory symptoms.
Neurological symptoms– occur in up to 10% of untreated people*, and may present days to months after infection. People may present with one or more of the following:
- Unilateral or bilateral facial nerve palsy (or, rarely, other cranial nerve involvement)
- Radiculopathy (usually associated with pain and/or paresis)
- Meningitis or (rarely) encephalomyelitis
- Mononeuropathy multiplex — involvement of multiple, anatomically unrelated nerves
Borrelia Lymphocytoma – This is uncommon in Europe, and extremely rare in the UK. It is a bluish-red, solitary swelling, with a diameter of up to a few centimetres, most often seen on ear lobes or nipples.
* According to other studies, Lyme neuroborreliosis may occur in 15-25% of UK cases.[5,6]
Ocular (eye) involvement is less common but may include conjunctivitis in the early stages of Lyme disease. Uveitis (inflammation of the middle layer of the eye) and keratitis (inflammation of the cornea) may also occur.
Consider the possibility of late Lyme disease in people with a history of a tick bite or possible exposure to ticks when they present with any of the following:
- Arthritis – Rare with UK-acquired infection, but more common when the disease is acquired in some other parts of Europe or in the US. Involves recurrent brief attacks of joint swelling in one or more large joints (most commonly the knee or, less frequently, a hip, ankle, shoulder, or temporomandibular (jaw) joint) and occasionally progresses to chronic arthritis. A large knee effusion (that is often out of proportion to the pain) is typical and a Baker’s cyst may develop and rupture.
- Neurological disease – Late neurological Lyme disease can present as a slowly progressive central nervous system disorder (encephalomyelitis) or peripheral neuropathy.
- Acrodermatitis chronica atrophicans – This is an uncommon, bluish-red discolouration and swelling, on the extensor surfaces of legs and arms, that develops several years after infection. There is often associated peripheral neuropathy.
1) Lyme borreliosis: clinical case definitions for diagnosis and management in Europe. Stanek, G., Fingerle, V., Hunfeld, K.-P., Jaulhac, B., Kaiser, R., Krause, a, et al. (2011). Clinical microbiology and infection, 17(1), 69-79.
2) Comparison of Findings for Patients with Borrelia garinii and Borrelia afzelii Isolated from Cerebrospinal Fluid. Strle et al. Clinical Infectious Diseases 2006; 43:704–10
3) Comparison of erythema migrans caused by Borrelia afzelii and Borrelia garinii Logar M, Ruzić-Sabljić E, Maraspin V, Lotric-Furlan S, Cimperman J, Jurca T, et al.. Infection. 2004 Feb;32(1):15–9.
5) Lyme disease surveillance in England and Wales, 1986-1998. Smith R, O’Connell S, Palmer S. Emerg Infect Dis. 2000;6(4):404–7
6) Neuroborreliosis in the South West of England. Lovett JK, Evans PH, O’Connell S, Gutowski NJ. Epidemiol Infect. 2008 Dec;136(12):1707–11.