Travel Health Information Sheets
- Risk for travellers
- Signs and symptoms
- Diagnosis and treatment
- Further references
Lyme disease is a zoonosis caused by a spirochete bacterium of the genus Borrelia. It is transmitted to humans by ticks. Of the 11 different species of the genus Borrelia, B. burgdorferi is the most common cause of human disease in North America. In Europe and Asia B. afzelii, B. garinii, and B. burgdorferi are the causative agents.
Ticks of the Ixodes species are responsible for transmitting Lyme disease; I. scapularis and I. pacificus are seen in North America and I. ricinus and I. persulcatus in Europe and Asia. Mice, other rodents and small mammals are the bacterial reservoirs; birds may also be a reservoir. Deer are an important host for adult ticks in the complex transmission cycle of Lyme bacteria.
The disease occurs in temperate regions of North America, Europe and Asia and is the most common tick borne infection in the United States (US). It gained its name from the first descriptions of clinical Lyme disease in Lyme, Connecticut, US in the mid 1970’s.
In 2011, 96% of Lyme disease cases in the USA were reported from 13 states: Connecticut, Delaware, Maine, Maryland, Massachusetts, Minnesota, New Hampshire, New Jersey, New York, Pennsylvania, Vermont, Virginia and Wisconsin. In 2011 in the US there were a total of 24,364 confirmed cases of Lyme disease with a national incidence rate of 7.8 cases per 100,000 population (Figure 1) .
Figure 1 Number of Lyme disease cases by county: United States, 2012. ( with permission).
In Europe, Lyme disease is widespread occurring between 35 °N and 60 °N, and generally below an altitude of 1,300 metres. In addition, at a local level, there are some hotspots with >100 cases per 100,000 population per year reported (e.g. parts of Slovenia, Germany and Austria, the Baltic coastline of southern Sweden, and some Estonian and Finnish islands) [2, 3]. The risk is considered to be higher for certain occupations (e.g. forestry work and farming), leisure activities (e.g. hunting, mushroom collecting and berry picking) and age groups (particularly children aged 5–14 years and adults aged 50–64 years).
Lyme disease does not occur in tropical regions or in Australia or New Zealand.
Seasonal variation in human cases occurs depending on the abundance and exposure to ticks. In northern and central European countries cases peak in June and July with a second peak occurring in late summer and autumn in more southern countries of Europe .
Most cases in England and Wales are diagnosed between June and October which corresponds with patterns of tick questing and abundance, or exposure through activities such as walking or camping in high risk environments. This peak is associated with infections acquired in both the UK and overseas (Figure 2).
Figure 2. Indigenous and overseas reports of Lyme borreliosis diagnosed in England and Wales; 2011
Lyme Disease in UK Travellers
In 2011, 197 patients (21% of all laboratory confirmed cases in England and Wales) reported overseas travel; most were in holidaymakers who presented with symptoms after visiting countries in continental Europe or North America [3, 4]. Countries visited include Poland (n=42), France (n=33), Scandinavian countries (n=30) and Germany (n=18). Many other countries were visited but by fewer than 10 cases.
Travellers acquire Lyme disease when they are bitten by Ixodes spp. ticks in forested, grassy, or woodland areas of endemic regions. Activities that might put a traveller at risk include camping, walking or working in these areas. Lyme disease has a seasonal transmission with highest risk periods during the spring, summer and autumn months .
The disease is transmitted by Ixodes spp. ticks through salivation during feeding . Ixodes ticks are also the vectors for other infections including tick borne encephalitis, rickettsial diseases, Coxiella sp., Anaplasma sp. and babesiosis. There are three stages of ticks (larvae, nymphs and adults) that feed only once during each stage. The development cycle of the ticks extends over two to three years. Larvae and nymphs take up the bacteria from reservoir hosts (usually small mammals such as mice) and transmit infection to humans when they are bitten. The nymph stage is usually responsible for transmitting infection. Larger mammals, such as deer, are not hosts for the organism but are necessary to maintain the adult population of ticks .
Ticks reside on ground level vegetation from where they can be brushed onto clothing or drop onto passing humans. They climb up the clothing until they find exposed skin to feed upon. The legs, groin, and axilla are common sites for ticks to attach.
Lyme disease is a multi-system infection that can occur in acute and chronic stages with remissions and exacerbations of clinical symptoms. The disease has also been known in Europe as erythema migrans, acrodermatitis chronica atrophicans, and Bannwarth’s syndrome.
The initial stage is characterised by a classic cutaneous lesion termed erythema migrans. This is seen in 70% to 80% of persons who are infected with B. burgdorferi . The lesion usually occurs at the site of the bite, developing 3 to 30 days (usually 7 to 10 days) following exposure. There may be an initial red macule or papule that expands over days to reach an average diameter of 15 cm. It typically has a bright red outer border with partial central clearing; however, the central clearing may be absent. The thigh, groin and axilla are common sites. The lesion is warm to touch but frequently painless and may go unnoticed by the patient if it is not in an easily seen area. Multiple, secondary lesions may develop when the organism disseminates to other sites of the body. Many patients will not remember a tick bite .
A cutaneous manifestation that is seen in Europe is acrodermatitis chronica atrophicans . This is a long-standing lesion with slow evolution from an initial red or bluish-red discolouration to atrophic skin changes that usually occur on the extensor surfaces of the hands.
The initial phase of erythema migrans may be accompanied by mild systemic symptoms of myalgias, fever, headache, and regional lymphadenopathy. These symptoms are more likely with Lyme disease acquired in North America compared with disease acquired in Europe .
With dissemination of the organism through the body there may be extracutaneous symptoms that can include meningitis, cranial nerve palsies (usually the facial nerve), and carditis manifesting as heart block.
Late symptoms can occur 3 to 4 months after an infection that has not been treated. Patients can experience arthritis of one or more joints (usually knee, elbow, or ankle) with swelling often without prominent pain, and that can persist for weeks, resolve, and then recur. Rarely, chronic neurologic symptoms of headache, encephalitis, and cognitive disorders will occur.
The diagnosis of Lyme disease is made on clinical grounds and is supported by serologic testing. Local laboratories do an antibody screen (ELISA). The UK national reference laboratory at PHE does a two tiered serological investigation consisting of an ELISA test and confirmatory IgM and IgG immunoblot.
Although culture and PCR can provide documentation of the presence of the organism, these are not routinely performed because of the low yield from culture and short duration bacteraemia [7, 8]. There is insufficient evidence to recommend tests such as Lymphocyte transformation tests.
Antibiotic therapy is of benefit in all stages of Lyme disease, but is most effective during the early stages. Erythema migrans should always be treated on clinical suspicion. Treatment recommendations for early stages including erythema migrans and cranial nerve palsies include: doxycycline, amoxycillin, or cefuroxime taken orally for 14 days [3, 8]. Parenteral antibiotics are usually required for neurologic complications, cardiac involvement and late manifestations such as recurrent arthritis [9, 10].
There is no vaccine against Lyme disease. Travellers to endemic areas should be advised to practice insect bite avoidance measures. In particular clothing should be treated with an insecticide, and travellers should be encouraged to tuck their trousers into their socks to prevent ticks from crawling up the legs [6, 7]. Persons should also apply repellents to exposed skin.
Ticks require several hours of feeding (24 to 72 hours) before transmitting Borrelia to humans . Therefore, travellers should check themselves frequently for ticks and remove them promptly using tweezers placed as close as possible to the skin followed by a slow pulling motion . Pets should be checked for ticks before being allowed into living areas.
In countries of high incidence, a single dose of doxycycline (200mg) may be offered to adult patients and to children 12 years and older, following the removal of an Ixodes tick that has been attached for more than 36 hours but less than 72 hours, and acquired in a Lyme endemic area. In a US study this has been shown to decrease the incidence of B. burgdoferi infection . Because of the possibility of different vector and organism dynamics in Europe and Asia, it is not known if this approach would be effective in these regions. It is not current UK practice to offer prophylaxis following a tick bite in UK affected areas.
1. Centers for Disease Control and Prevention. Lyme Disease. [Accessed 18 March 2014]. Available at: http://www.cdc.gov/lyme/stats/index.html
2.Rizzoli A, H C Hauffe HC, Carpi G et al. Lyme borreliosis in Europe. Eurosurveillance, Volume 16; 27, 07 July 2011. [Accessed 18 March 2014]. Available at http://www.eurosurveillance.org/ViewArticle.aspx?ArticleId=
3. British Infection Association. The epidemiology, prevention, investigation and treatment of Lyme borreliosis in United Kingdom patients: A position statement by the British Infection Association. Journal of Infection (2011) 62, 329-338
4. Public Health England. Lyme borreliosis in England and Wales; 2011. [Accessed 18 March 2014]. Available at: http://www.hpa.org.uk/Topics/InfectiousDiseases/InfectionsAZ/
5. Public Health England. Epidemiology of Lyme borreliosis in the UK. 1 May 2013. [Accessed 18 March 2014]. Available at: http://www.hpa.org.uk/webw/HPAweb&HPAweb
6. Health Protection Agency. General Information about Lyme Borreliosis. 23 March 2012. [Accessed 18 March 2014]. Available at; http://www.hpa.org.uk/webw/HPAweb&HPAweb&HPAweb
7. Public Health England. Lyme disease diagnostic service. [Accessed 18 March 2014]. Available at http://www.hpa.org.uk/Topics/InfectiousDiseases/Infections
9. Wormser G, Dattwyler R, Shapiro E 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. CID 2006; November 1:1089-134.
10. Ljostad U, Skogvoll E, Eikellans E et al. Oral doxycycline versus intravenous ceftriaxone for European Lyme neuroborreliosis: a multicentre non-inferiority, double-blind randomised trial. Lancet Neurology 2008;7:690-695
11.Public Health England. Ticks and your health. Information about tick bite risks and prevention. [Accessed 18 March 2014]. Available at: http://www.hpa.org.uk/webc/HPAwebFile/HPAweb_
12. Nadelman RB, Nowakowski J, Fish D, et al. Prophylaxis with single-dose doxycycline for the prevention of Lyme disease after an Ixodes scapularis tick bite. N Engl J Med 2001;345:79-84.
British Infection Association. The epidemiology, prevention, investigation and treatment of Lyme borreliosis in United Kingdom patients: a position statement by the British Infection Association. Journal of Infection 2011; 62:329–38.
Smith R, O’Connell S, Palmer S. Lyme disease surveillance in England and Wales, 1986 1998. Emerging Infectious Diseases 2000; 6:404–7.
Mygland A, et al. EFNS guidelines on the diagnosis and management of European Lyme neuroborreliosis. European Journal of Neurology 2010; 17:8–16, e1–4.
Stanek G, et al. Lyme borreliosis: clinical case definitions for diagnosis and management in Europe. Clinical Microbiology and Infection 2011; 17:69–79.
O’Connell S. Lyme borreliosis: current issues in diagnosis and management. Current Opinion in Infectious Diseases 2010; 23:231–5.
Advice current at 19 March 2014
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