oPatientPlus articles are written by UK doctors and are based on research evidence, UK and European Guidelines. They are designed for health professionals to use, so you may find the language more technical than the condition leaflets.
This disease was formally described following the investigation of a collection of patients with rashes and swollen joints occurring in Lyme, Connecticut in the 1970s.
Lyme disease is caused by the bacterium Borrelia burgdorferi, which is a spirochaete. Recent studies have shown that there are several genospecies and the group as a whole is referred to as B. burgdorferi sensu lato. Humans may contract it when they are bitten by ticks of the Ixodes species which are infected by B. burgdorferi.
The disease is caused by the infection and the body's immune response to infection. Different strains of Borrelia spp. cause different clinical manifestations of Lyme disease and this explains differences between the disease in Europe and the disease in the USA.
Although there is a rising incidence, this is likely to be due to better detection and surveillance. It is still a rare disease.
The spirochaete responsible is transmitted from host to host by Ixodes spp. or deer ticks. Understanding the life cycle of these organisms gives better understanding of the epidemiology, other clinical aspects and prevention of Lyme disease. The Ixodes tick:
- Is made up of different species, found in different areas of the world.
- Emerges in a larval form in the summer and feeds just once on a host animal (often a mouse).
- In the spring the larva becomes a nymph and feeds, again only once, from a similar animal host. Humans can be victims in the nymph stage (most tick bites in humans occur at this time in spring and early summer).
- In the autumn the adult tick finally emerges to feed on deer, again just once. Humans can be hosts at this stage.
The spirochaete responsible:
- Is transmitted by the tick. The tick must have fed on a host significantly infected with spirochaete to pass on the infection to man.
- Once it infects the tick, it has to go through a particular cycle of multiplication and dissemination to salivary glands within the tick before it can be passed on to the animal victim. Hence, a tick must be attached for some time to a person before infection can be passed on.
Once the spirochaete infects the host there may be one of several consequences:
- The infection is cleared by host defences. This means the person will have had no clinical manifestations, be asymptomatic but seropositive.
- The organism spreads by direct invasion. This is believed to be a feature in early disease. For example, erythema migrans is thought to result from the inflammatory response to direct invasion of the organism in the skin.
- The organism excites an immune response in the host, which causes a variety of clinical manifestations around the body. In such cases there is no evidence of direct bacterial invasion. The manifestations of Lyme disease are related to the particular Borrelia spp. strain involved. Particular strains are found in different countries. For example:
- B. garnii, found in Europe, is associated with neurological disease.
- B. afzelii from Europe is associated with acrodermatitis chronica atrophicans.
- B. burgdorferi sensu stricto predominates in the USA with an associated pattern of musculoskeletal complications.
- B. valaisiana has a relatively high prevalence in British ticks, and does not appear to be associated with manifestations of disseminated borreliosis, which may explain the low incidence of Lyme borreliosis in the UK.
- In the UK, areas where infection is acquired include Exmoor, the New Forest, the South Downs, parts of Wiltshire and Berkshire, Surrey, West Sussex, Thetford Forest, the Lake District, the North Yorkshire moors and the Scottish Highlands.
- About 15% of confirmed cases are reported to have been acquired abroad and mostly by holidaymakers. The majority are acquired in the USA, France, Germany, Scandinavia and other northern and central European countries. Recently numbers of cases in the UK acquired in central and eastern Europe have been increasing. The infection can also be found in temperate forested areas of Asia, including Russia, China and Japan.
- Laboratory-confirmed reports of Lyme borreliosis have risen steadily since reporting began in 1986. Several factors have contributed to the observed increase, including increased awareness of the disease, access to diagnostic facilities, more sensitive diagnostic methods, the enhanced surveillance scheme (introduced in 1996) and, since 2000, more complete reporting of cases. Other possible factors producing a real increase include successively mild winters increasing the geographical range of areas with climate suited to the tick both in the UK and Europe, more holiday travel to high endemic areas and the increasing popularity of holidays involving walking and mountain biking.
- Over 6,900 cases have been reported in England and Wales since enhanced surveillance began in 1997. Mean incidence rates are now approximately 1.73 cases per 100,000 population.
- Cases occur throughout the year but the peak is in the summer months.
- Lyme disease affects people of all ages and gender but the peak ages affected are 45-64, and 24-44.
Some of those infected will have no symptoms. Patients with Lyme disease may not remember being bitten by the often innocuous tick. The presentation depends on the stage of disease:
Early Lyme disease (stage 1, or localised disease)
The characteristic manifestation is erythema migrans:
- A circular rash at the site of the infectious tick attachment that radiates from the bite, within 3-36 days.
- In Europe this has been found to be the presenting sign in up to 90% of cases and may be the only manifestation.
- The rash is round or oval, and pink, red or purple. There is often central sparing giving a target-like appearance, and the diameter is usually larger than 5 cm.
- The nature of the rash and the likelihood of its presence are partly dependent on the species involved and therefore differ between continents.
- Untreated, this can last for some weeks, but eventually resolves.
- In Europe, around a third have associated nonspecific flu-like symptoms.
Disseminated Lyme disease (stage 2 disease)
This disseminated stage is still considered to be early infection and occurs days to months later, with:
- Flu-like illness: symptoms include joint and muscle pains, headache, fever, tiredness, nausea or vomiting. This is more common in the USA.
- Neurological disorders or neuroborreliosis (10% of untreated cases):
- In Europe this is the second most common presentation after erythema migrans.
- Unilateral or bilateral facial nerve palsies are the most common neurological manifestations in Europe and the USA. Rarely, other cranial nerves may be involved.
- Meningism and meningitis may occur alone or with other neurological manifestations. It is usually at the mild end of the spectrum but can be more severe.
- Mild encephalitis producing malaise and fatigue.
- Peripheral mononeuritis
- Lymphocytic meningoradiculitis (Bannwarth's syndrome), which is more common in Europe than the USA.
- Cardiovascular problems: myopericarditis may occur but is rare in the UK. This presents with syncope, chest pain or breathlessness. ECG shows atrioventricular or first degree heart block.
- Lymphocytomas: these are bluish-red nodular lesions infiltrated with lymphocytes. They typically appear on the earlobe or nipple. They occur occasionally in Europe and are very rare in the USA.
Late manifestations of Lyme disease (stage 3 disease)
- Arthritis: this is uncommon in the UK, but may be present if infection is acquired in the USA. There are usually recurrent attacks in large joints, particularly the knee. It often presents as a large knee effusion, or a Baker's cyst. There is occasional progression to a chronic arthritic condition.
- Acrodermatitis chronica atrophicans: this is a rare skin condition that can occur years after the infection. Extensor surfaces of the limbs develop blue-red discolouration and swelling. There can be associated peripheral neuropathy.
- Late neurological disorders: these include polyneuropathy, chronic encephalomyelitis, vertigo and psychosis.
- 'Post-Lyme syndrome': described as similar to chronic fatigue syndrome or fibromyalgia 
Of erythema migrans:
- Hypersensitivity reaction to a tick or other insect bite. (Less than 5 cm and usually resolves in a few days)
- Erythema annulare centrifugum
- Erythema multiforme
- Granuloma annulare
Infections which can mimic certain aspects of the typical multisystem illness seen in chronic Lyme disease include:
- Viral infections - for example:
- Parvovirus B19
- West Nile virus infection
- Bacterial infections - for example:
When to test
Before requesting tests, assess the risk of exposure from the history. Include on the request the date of the tick bite and the onset of illness.
In patients with erythema migrans:
- Testing is not usually necessary with a history of tick bite (or possible exposure).
- This characteristic rash with a history of tick bite or exposure is enough to make a diagnosis.
In primary care, testing should be considered:
- With erythema migrans but with no tick bite (or tick exposure) and no other features of Lyme disease.
- When there is isolated unilateral facial palsy (as with Bell's palsy) and Lyme disease needs excluding because of a history of tick bite (or tick exposure).
In patients with other neurological symptoms, joint or cardiac symptoms:
- Test in primary care only after specialist advice.
- Usually such patients require hospital admission or urgent specialist assessment.
All testing for Lyme disease is centralised at Public Health England (PHE) Porton.
Antibodies to B. burgdorferi
This blood test uses the internationally recognised two-step testing approach:
The initial enzyme immunoassay has a high false-positive rate (it can be positive with other conditions - for example, glandular fever, syphilis, rheumatoid arthritis and some autoimmune diseases). Therefore, a second step test, employing immunoblotting, is used to re-test positive samples to confirm the diagnosis.
It takes several weeks for the antibody response to reach a detectable level so if tested early, the result may be negative, and may need repeat. In the first two weeks after infection only 30% will be positive, but this increases to 80% by six weeks. Over 99% with late-stage illness will test positive.
It is possible to have antibodies without current infection.
Polymerase chain reaction (PCR)
This detects the bacterial DNA, but is only useful in a few cases. It may be used occasionally on fluid from joint aspirations or skin samples.
NICE CKS 2010 recommends that GPs manage the possible presentations, listed below, as follows:
How to manage a tick bite
- If the tick is still attached, remove it.
- Grip the tick with fine-tipped or precision tweezers and pull upwards without twisting.
- Clean the skin afterwards with an antiseptic preparation.
- The tick may be disposed of in normal household rubbish.
- Do NOT use petroleum jelly, alcohol, nail varnish remover, or burn the tick off.
- For those regularly exposed to ticks, removal devices are available from veterinary surgeries or pet shops.
- Antibiotic prophylaxis is NOT recommended routinely in the UK following a tick bite. (Seek advice in immunocompromised or high-risk individuals.)
How to manage a patient with erythema migrans and a history of tick bite or likely exposure
- Blood tests are NOT necessary; the diagnosis can be made clinically.
- Treat with an oral antibiotic for two weeks.
- Doxycycline 100 mg bd or amoxicillin 500 mg tds.
- Cefuroxime 500 mg bd if both are contra-indicated and there is no history of anaphylaxis with penicillins.
- If unable to distinguish between cellulitis and erythema migrans, use co-amoxiclav, cefuroxime or amoxicillin with flucloxacillin.
- For children aged over 12, use doxycycline 100 mg bd or amoxicillin 50 mg/kg/day in divided doses (maximum 500 mg per dose).
- For children aged under 12, use amoxicillin 50 mg/kg/day in divided doses (maximum 500 mg per dose) or cefuroxime 30 mg/kg/day in two divided doses (maximum 500 mg per dose and assuming there is no history of anaphylaxis with penicillins).
- For breast-feeding women, use amoxicillin or cefuroxime.
- For pregnant women, use amoxicillin or cefuroxime and inform an obstetrician. Lyme disease carries little direct risk to the pregnancy; however, there is a possible risk of uterine contraction following a reaction to treatment (Jarisch-Herxheimer reaction).
How to manage a patient with possible erythema migrans but no history or likely exposure to tick bites
- Seek advice from an infectious disease specialist or dermatologist about the need for testing and antibiotics.
How to manage a patient with flu-like symptoms and a history of exposure to tick bites
- Seek advice from an infectious disease specialist.
How to manage a patient with an isolated facial nerve palsy and a history of recent erythema migrans or exposure to tick bites
- Test for antibodies to B. burgdorferi sensu lato.
- Discuss with an infectious disease specialist.
- Usually, treatment will be with oral antibiotics as per erythema migrans.
How to manage a patient with any other systemic manifestations (other neurological, cardiac or joint involvement)
- Refer for immediate specialised assessment.
- The patient may require IV antibiotics.
- Patients with cardiac symptoms may require temporary pacing.
- Occasionally, patients with persistent arthritis may require an arthroscopic synovectomy.
How to manage a patient with possible acrodermatitis chronica atrophicans, or borrelial lymphocytoma
- Refer to a dermatologist for diagnosis and treatment.
Lyme disease is rarely fatal. Prognosis is usually good, even in untreated cases.
The natural disease course of European borreliosis is not well defined and the effect of antibiotic treatment is unclear. There are no UK studies on the outcome of treatment.
Measures to reduce infection in areas associated with ticks:
- Wear long hair under a hat.
- Keep to the middle of paths and avoid unnecessary brushes with foliage.
- Avoid wooded areas where possible. Mown grass areas are less likely to have ticks in them.
- Keep legs and arms covered (wear trousers inside socks).
- Use insect repellent.
- Inspect skin regularly during the day in at-risk areas (especially the groin, axillae and hairline).
Further reading & references
- Tick removal; Lyme Disease Action
- European Concerted Action on Lyme Borreliosis (EUCALB)
- Due C, Fox W, Medlock JM, et al; Tick bite prevention and tick removal. BMJ. 2013 Dec 9;347:f7123. doi: 10.1136/bmj.f7123.
- Lyme borreliosis/Lyme disease; Public Health England
- British Infection Association; The epidemiology, prevention, investigation and treatment of Lyme borreliosis in United Kingdom patients: a position statement by the British Infection Association. J Infect. 2011 May;62(5):329-38. doi: 10.1016/j.jinf.2011.03.006. Epub 2011 Mar 21.
- Lyme disease; NICE CKS, January 2010
- Wormser GP, Dattwyler RJ, Shapiro ED, et al; The clinical assessment, treatment, and prevention of lyme disease, human granulocytic anaplasmosis, and babesiosis: clinical practice guidelines by the Infectious Diseases Society of America. Clin Infect Dis. 2006 Nov 1;43(9):1089-134. Epub 2006 Oct 2.; (reviewed 22/4/2010 by IDSA - no changes made to guidelines)
- Guidelines on the diagnosis and management of European Lyme neuroborreliosis; European Federation of Neurological Societies (2010)
- Dinser R, Jendro MC, Schnarr S, et al; Antibiotic treatment of Lyme borreliosis: what is the evidence? Ann Rheum Dis. 2005 Apr;64(4):519-23.
- Prevention and control of tick-borne disease in Europe - Information to healthcare professionals; European Centre for Disease Prevention and Control
Disclaimer: This article is for information only and should not be used for the diagnosis or treatment of medical conditions. EMIS has used all reasonable care in compiling the information but make no warranty as to its accuracy. Consult a doctor or other health care professional for diagnosis and treatment of medical conditions. For details see our conditions.
Dr Colin Tidy
Dr Mary Harding
Prof Cathy Jackson