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Erythema chronicum migrans is a characteristic clinical feature of Lyme disease (Lyme borreliosis). It is a distinctive rash, which occurs in the majority of people infected with Borrelia burgdorferi. This infection is transmitted to humans by the bite of a tick from the genus Ixodes.
- Nearly 8,000 cases of Lyme disease have been reported in England and Wales since enhanced surveillance began in 1997. Mean annual incidence rate is now approximately 1.73 cases per 100,000 population.
- Whilst Lyme disease can occur in people of all ages and gender, the peak age range affected is 45-64, followed by 24-44.
- 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.
- In Europe erythema chronicum migrans occurs as a presenting feature in up to 90% of those infected. Presentation does appear to depend upon the Borrelia species involved; therefore, in other parts of the world the rash may be a less common presenting sign.
- The characteristic manifestation of early Lyme disease (stage 1) is erythema chronicum migrans: a circular rash at the site of the infectious tick attachment, which radiates from the bite. It can appear within 3-36 days, but typically in 7-10.
- It starts as a red macule or papule at the site of the tick bite after a (typically 7- to 10-day) delay.
- 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
- Common areas include the popliteal fossa, groin, the axilla, the thorax and the trunk. The hairline and scalp are especially common in children.
- It may be associated with other symptoms of infection, including fatigue, myalgia, arthralgia, headache, fever, stiff neck, and regional lymphadenopathy.
- It may also be associated with later developments such as carditis, neurological disease, arthritis, and acrodermatitis chronica atrophicans (a swollen, bluish-red skin lesion on a distal extremity).
- Local tick bite reactions
- Tinea (ringworm)
- Insect bites
- Discoid eczema
- Contact dermatitis
- Erythema multiforme
- Granuloma annulare
- Erythema annulare centrifugum
- In the presence of a characteristic rash and history of tick bite, investigation is not be required.
- Discuss necessity and timing of testing with a local microbiologist
- Serology may be necessary. All testing for Lyme disease is centralised at Public Health England (PHE) Porton. Blood is tested for antibodies to B. burgdorferi.
Although the rash will resolve spontaneously over weeks or months, antibiotics hasten resolution and help prevent progression to Lyme disease:
- Doxycycline is the antibacterial of choice for early Lyme disease. It should be given in a dose of 100 mg twice daily for 14 days. It is contra-indicated in children under the age of 12, and in pregnant and breast-feeding women.
- Amoxicillin (500 mg three times a day) or cefuroxime (500 mg twice a day) are alternatives if doxycycline is contra-indicated. Again, treatment should be for 14 days.
- Children under the age of 12 should have amoxicillin first-line (50 mg/kg/day in three divided doses) or cefuroxime (30 mg/kg per day in two divided doses) for 14 days.
- Macrolides such as azithromycin or clarithromycin should be reserved as third-line treatment as they are not as effective as the aforementioned antibiotics.
- Avoid exposure to tick bites.
- Remove ticks as soon as possible. Ticks take some time to transmit infection, so this may be prevented if removed quickly.
- Antibiotic prophylaxis can be offered in endemic areas under certain circumstances if the tick bite can be positively identified.
Further reading and references
; DermIS (Dermatology Information System)
; European Federation of Neurological Societies (2010)
; European Centre for Disease Prevention and Control
; Public Health England
; J Infect. 2011 May62(5):329-38. doi: 10.1016/j.jinf.2011.03.006. Epub 2011 Mar 21.
; NICE CKS, January 2010 (UK access only)
; 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 143(9):1089-134. Epub 2006 Oct 2.
Hi! I had bad bites 9 years ago in May 2010. They came up a week after returning from holiday in Thailand, but I'm also very outdoorsy so could have been from home in UK. They went bad and after a...BluebellBunny
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