What is Lyme disease?

Lyme disease, also known as Lyme borreliosis, is an infectious disease caused by the bacterium Borrelia burgdorferi.[1] For more detail, see our page on the bacteria.

How does Lyme disease infection occur?

In nearly all recorded cases it is passed to humans by the bite of a tick infected with these bacteria. [1] In a population of ticks, only some will carry the infection. LDA has highlighted the need for further research to resolve ongoing uncertainty concerning the possibility of alternative means of transmission.

What is Borreliosis?

The disease resulting from infection with Borrelia burgdorferi is referred to as Lyme disease or Lyme borreliosis. There are many species of Borrelia bacteria worldwide, not all of them cause disease.  What was originally thought to be one species – B burgdorferi – is now known to be several, and three of these known to cause disease are present in UK ticks. They are B burgdorferi (sensu stricto – in the strict sense), Borrelia afzelii, and Borrelia garinii. [1] They are very closely related and all cause a broadly similar disease process. In addition some UK ticks carry Borrelia miyamotoi [11] which is more closely related to the relapsing fever group of Borrelia. An infection caused by Borrelia bacteria can be called a ‘Borreliosis.’

How does Lyme disease start?

A clinical case of Lyme disease occurs when a person is infected by a tick bite. Symptoms appear on average 14 days after the tick bite. However, the incubation period may last between two days and 3 1/2 months.[3] The bacteria can enter a phase in which they do not cause symptoms but are still present. They may still have the potential to cause active disease at a later stage.[4]

Is Lyme disease a new illness?

Studies of the DNA taken from ticks in the Natural History Museum show Borrelia bacteria were in the UK in Victorian times but this may have reflected the presence of the non-pathogenic B valaisianna which is very common in UK ticks. Lyme borreliosis has been known in mainland Europe for more than a century, but the first recorded case of an erythema migrans in the UK was in 1977 and the number of Lyme disease cases has been rising since then.[5]


What are the symptoms of Lyme disease?

Lyme disease can affect any part of the body and cause many different symptoms. The commonest symptoms relate to the person feeling unwell, having flu-like symptoms, extreme tiredness, muscle pain, muscle weakness, joint pain, upset digestive system, headache, disturbances of the central nervous system and a poor sleep pattern. An early symptom is an expanding ‘bull’s eye’ rash, but many people do not notice this. The rash is called erythema migrans or EM rash. The list of symptoms known to be associated with Lyme disease is long and diverse. The symptom pattern varies from person to person.[1,6]

What are the commonest symptoms at onset?

Early symptoms can include feeling unwell or ‘flu-like’, EM rash, headache, stiff neck, muscle pain, tender glands and sensitivity to temperature, sound and light levels.[1]

Does Lyme disease affect mental functioning?

Like some other diseases caused by spirochaetes, there is a possibility that the infection can cross into the central nervous system. If the infection proceeds along this course then symptoms that affect mental function may occur.[2]


What is the treatment for Lyme disease?

Treatment is with antibiotics according to NICE Guideline, and is most effective if started as early as possible in the disease. Those treated promptly usually make a complete recovery. The cause of persisting symptoms is not known. There is some scientific  evidence that suggests re-treatment, longer courses of antibiotics and possibly different antibiotics may be necessary in some cases, but research continues. [6,7] Although some people recover without treatment (as in other diseases), if there is delay before treatment begins, there may be less chance of a full recovery. The outlook varies from person to person. Whilst it is extremely unusual for the illness to be fatal, symptoms can range from mild to very severe. It is not in a patient’s best interests for the disease to remain untreated.

Will my doctor treat me for Lyme disease?

If you have this diagnosis your doctor should treat you. However, many doctors are not familiar with treating Lyme disease patients.  Always try to keep your GP involved and informed. See the page Resources/For patients for information to give to your doctor. A worsening of symptoms called a Jarisch-Herxheimer reaction may complicate the start of treatment. This does not occur in every case but if it does further medical advice should be sought. Lyme disease is an infectious disease and the primary aim of treatment is eliminating the infection with the help of antibiotics. Other medicines may also have a place in treatment. Response to treatment varies from patient to patient.


Is there a test for Lyme disease?

There are several laboratory tests that aim to detect this infection, however, none of them can be guaranteed to rule out Lyme disease. If positive they can be used to support the diagnosis.

How do I know if I’ve got Lyme disease?

Lyme disease is not an easy diagnosis to make. This is especially so if the patient does not see a rash and does not recall a tick bite. If a patient remembers a tick bite and then becomes unwell, Lyme disease is a possibility. Negative test results do not necessarily exclude a diagnosis of Lyme disease and the diagnosis may sometimes be made on clinical grounds alone. See our Self Help page.

Lyme in the UK

What is the incidence of Lyme disease in the UK?

The number of cases confirmed by laboratory testing in the UK has risen from 346 in 2003 to about 2000 in 2019. Public Health England (PHE) acknowledges that confirmed cases do not necessarily reflect all the cases of the disease. Recent research suggests the incidence is at least twice the number of reported cases and may be significantly higher. [10] Since full recovery may not take place in many cases, the total number of people affected is accumulating.

Who gets Lyme disease and why?

In the United Kingdom, Lyme disease is known to be carried mainly by small mammals, such as mice and voles, and birds, though larger mammals can also carry it. Ticks feeding on these animals pick up the Lyme disease bacteria and pass them on to the next animal they feed on. Ticks can also feed on deer, cattle and sheep, which appear to kill the bacteria in the tick (9).  Ticks cannot stand drying out, so tend to live in long grass, gardens, woods and moorland. People who live, work or have a holiday in places that can harbour ticks are likely to be at greater risk, as are those in urban areas with overgrown gardens or with extensive parks. Anyone can get Lyme disease if a tick that is carrying the infection has bitten them.

Do other diseases accompany Lyme disease?

Several other infections can sometimes be found in tick saliva. These can also be transmitted as the tick feeds and may complicate the symptoms and outlook. See our page on tick-borne diseases in the UK.

Can Lyme disease be prevented?

There are many measures you can take to protect yourself from contracting this infection.[8] There is however, no vaccine available at present. Prevention relies on people being aware of the risk that ticks present and using sensible measures to avoid being bitten. These measures include wearing suitable clothing and checking the skin for ticks. It is also essential to know how to remove a tick properly, as quickly as possible, and to go promptly for medical advice if you notice any symptoms.


  1. Stanek G, Wormser GP, Gray J, Strle F. Lyme borreliosis. Lancet. 2011 Sep 6;6736(11):1–13.
  2. Williams F, Ginsberg L, Brenner R, Cohen A. An exotic cause for confusion in the garden. Pract Neurol. 2008 Aug;8(4):256–9.
  3. Logar M, Ruzić-Sabljić E, Maraspin V, Lotric-Furlan S, Cimperman J, Jurca T, et al. Comparison of erythema migrans caused by Borrelia afzelii and Borrelia garinii. Infection. 2004 Feb;32(1):15–9
  4. Matera G, Labate A, Quirino A, Lamberti AG, Borzì G, Barreca GS, et al. Chronic neuroborreliosis by B garinii: an unusual case presenting with epilepsy and multifocal brain MRI lesions. New Microbiol. 2014;37:393–7.
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  9. Richter D, Matuschka F-R. Elimination of lyme disease spirochetes from ticks feeding on domestic ruminants. Appl Environ Microbiol. 2010 Nov;76(22):7650–2
  10. Tulloch, John S P et al. 2020. “A Descriptive Epidemiological Study of the Incidence of Newly Diagnosed Lyme Disease Cases in a UK Primary Care Cohort, 1998-2016.” BMC Infectious Diseases 20 (1): 285.
  11. Layzell, Scott J. et al 2018 “Prevalence of Borrelia Burgdorferi and Borrelia Miyamotoi in Questing Ixodes Ricinus Ticks from Four Sites in the UK.” Ticks and Tick-Borne Diseases 9 (2): 217–24.