Tick bite and early Lyme borreliosis
BMJ2012;344doi: 10.1136/bmj.e3124(Published 14 May 2012)
Cite this as:BMJ2012;344:e3124
Christopher J A Duncan, research fellow12, George Carle, general practitioner3, R Andrew Seaton, consultant in infectious diseases and general (internal) medicine1
1Brownlee Centre for Infection, Tropical Medicine and Counselling, Gartnaval Hospital, Glasgow G12 0YN, UK
2Sir William Dunn School of Pathology, Oxford OX1 3RE, UK
3Kyles Medical Centre, Tighnabruaich, Argyll PA21 2BE, UK
Correspondence to: C J A Duncan firstname.lastname@example.org
Accepted 6 February 2012
A 48 year old man removed two ticks attached to his leg while walking in the Scottish Highlands. A week later he develops a rash and consults you worried about Lyme disease.
What you should cover
Epidemiology—Lyme borreliosis is the commonest tick-borne infection in the northern hemisphere. It is relatively uncommon in the UK overall (about 1200 cases in 2009), but marked geographical variation is observed. Risk is highest in rural forested areas and heathland such as the Highlands (incidence 56.35/100 000 in 2009-101), Lake District, and New Forest. Some 15–20% of infections are acquired in Europe or the US. There has been a steady rise in cases diagnosed in the UK over the past decade.2 3
Risk assessment—Ask about duration of hard bodied (Ixodes) tick attachment, with or without engorgement
(fig 1⇓). Transmission of pathogenic Borrelia species is unlikely if ticks are attached for <24 hours and unengorged.2 4
Fig 1 Fully engorged female Ixodes ricinus (courtesy of Dr Alan S Bowman, University of Aberdeen)
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Tick bite and early Lyme borreliosis
Re: Tick bite and early Lyme borreliosis
25 June 2012
Sandra Pearson, Consultant Psychiatrist
Medical Director, Lyme Disease Action UK, PO Box 235, Penryn. TR10 8WZ
The focus on Lyme disease in the current issue is timely since it helps raise awareness of Lyme disease, particularly at a time of year when the incidence is highest and the need for increased awareness and vigilance amongst doctors needs to be raised. However, in our view, there is regrettably a missed opportunity in terms of the quality and bias of the information that has been provided for BMJ readers.
The true incidence of Lyme disease in the UK is unknown but it is certainly more common than is thought. An audit at a highly aware GP Practice in Scotland has found an incidence of 370/100,000 population, based on clinical diagnosis of the erythema migrans rash, in contrast to the recorded (laboratory confirmed) 17/100,000 in the surrounding area. (Private communication) Although one practice is a small sample, it seems perfectly possible from this that 95% of cases are not entering official statistics: a few because they are diagnosed without a blood test; the majority because they are simply not diagnosed at all.
This article quotes the British Infection Association Position paper, and recommends it as useful reading (1), in saying that “Erythema migrans occurs in 90% of symptomatic Lyme borreliosis 2–40 days after exposure”. This is a seriously misleading statement based on surveys in continental Europe where both doctors and the public are more aware of Lyme disease and the significance of a rash. It is notable that two studies of groups of UK patients treated for Lyme disease found 77% (3) and 64% (4) had a rash thought to be erythema migrans. The rash may be on the back of the body and not seen, present behind the hair-line in children or may simply be ignored and forgotten by the time later symptoms develop.
This is not the only important point where the BIA statement misleads. A full comment on the BIA paper, written at the request of the BIA president so she could put it to the BIA Council, can be read on the Lyme disease Action website (5). The BIA paper aims to provide information for patients and doctors but ultimately provides a simplistic, inappropriately reassuring and arguably complacent account of this spirochaetal disease.
This issue of the BMJ continues the theme of ‘Communicating Risk’ but the 10-minute consultation fails to mention that only 15-20% of ticks are thought to be infected with Borrelia. The image of the massively engorged adult tick on the cover belies the fact that the most common vector for transmission of Lyme disease to humans is the nymphal stage which, being the size of a poppy seed, may well go unnoticed. Infected ticks may act as host for a number of other zoonotic pathogens: Babesia, Anaplasma, Bartonella, Rickettsia and some viruses which may also cause disease in humans and cause a more severe illness if present as a co-infection.
Epidemiological risk is also misrepresented: “forested” areas implies to most people man made forests. Dobson et al recently reported (6) “We see no biological reason to suppose, nor epidemiological data to suggest, that the New Forest, for example, is any more hazardous than large patches of similar woodland elsewhere in the UK, despite its reputation as a hotspot for ticks and Lyme disease.” Duncan does not mention the urban risks from the hedgehog tick and the fox tick.(7)
It is a pity that the resources commended to doctors are either unaccredited sources (the BIA paper, HPA website) or are geared towards the USA (Wolters Kluwer Health). Doctors could more usefully be referred to the Lyme Disease Action website which is accredited to the Department of Health’s Information Standard.
1. British Infection Association. The epidemiology, prevention, investigation and treatment of Lyme borreliosis in United Kingdom patients: A position statement by the British Infection Association. The Journal of infection. 2011 May;62(5):329–38.
2. Smith R, O’Connell S, Palmer S. Lyme disease surveillance in England and Wales, 1986 1998. Emerging infectious diseases [Internet]. 2000;6(4):404–7. Available from: http://www.pubmedcentral.nih.gov/articl ... 8&tool=p...
3. Dillon R, O’Connell S, Wright S. Lyme disease in the U.K.: clinical and laboratory features and response to treatment. Clinical Medicine. 2010 Oct; 10(5):454–7.
4. Lovett JK, Evans PH, O’Connell S, Gutowski NJ. Neuroborreliosis in the South West of England. Epidemiology and infection. 2008 Dec;136(12):1707–11.
5. http://www.lymediseaseaction.org.uk/res ... uidelines/
6. Dobson ADM, Taylor JL, Randolph SE. Tick (Ixodes ricinus) abundance and seasonality at recreational sites in the UK: Hazards in relation to fine-scale habitat types revealed by complementary sampling methods. Ticks and Tick-borne Diseases. 2011 Jun 2(2):67–74.
7. Couper D, Margos G, Kurtenbach K, Turton S. Prevalence of Borrelia infection in ticks from wildlife in south-west England. The Veterinary record. 2010 Dec 25;167(26):1012–4.
Competing interests: None declared