CLINICAL RISK REDUCTION


Lyme borreliosis – L


Dr James Douglas provides a useful summary of this rare but oſten debilitating condition


YME borreliosis (previously Lyme disease) is caused by a tick-borne spirochete and is an important zoonosis seen with increasing


prevalence in Scotland and parts of England, including the New Forest. Primary Lyme borreliosis can easily be prevented by tick removal and the rash cured with antibiotics but the secondary disease has a gathering clinical reputation as a rare multi-system mimic. Lyme disease was first described as an outbreak of


juvenile arthritis in Lyme, Connecticut, in the USA in 1975. It has subsequently become widely prevalent across Northern Europe along with other tick-borne diseases, including viral tick-borne encephalitis (not yet reported in the UK). In Scotland approximately 200 people per year have new positive serology1


but there is a much greater


disease burden being reported by GPs who make the clinical diagnosis of erythema migrans (see image on page opposite). Te exact prevalence of erythema migrans2


is uncertain because the Lyme serology is


negative. GPs, A&E, out-of-hours and relevant specialists all need to be aware of the presentations of Lyme borreliosis.


Prevalence and ecology A survey of Scottish blood donors (n=1440) showed 4.2 per cent positive Lyme serology3


, although with


regional variations in prevalence north and west. Highland has the highest percentage of seropositive donors at 8.6 per cent. Te interpretation of these data is difficult but may indicate recovery by human host immunity in the healthy population of Scottish blood donors, who may be more likely to engage in outdoor activities. Tere are no case reports worldwide for transfusion transmitted Lyme borreliosis. In Scotland, the Ixodes ricinus ticks transmits the


Borrelia spirochete by attaching to the human host and injecting its stomach contents over about 24 hours. Te tick can be widely distributed in affected areas including moorland, gardens and picnic sites4


References


1. Mavin S, Watson EJ, Evans R 2015 Distribution and presentation of Lyme borreliosis in Scotland - analysis of data from a national testing laboratory. JR Coll Physicians Edinb 45:196- 200


2. British Infection Association 2011 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 62: 329-338


3. Munro H, Mavin S, Duffy K, Evans R, Jarvis LM 2015 Letter to the Editor: Seroprevalence of Lyme Borreliosis in Scottish blood donors Transfusion Medicine. 25: 284-286


.


It lives at ground level in bracken and grass, being passed around by rodents, birds, deer and sheep. Te ticks attach themselves to humans on legs, behind the knees, in groins, armpits and the natal cleſt; thus the patient may not recall a tick bite or rash. Tere is


16


4. James MC, Bowman AS, Forbes KJ, Lewis F, McLeod JE, Gilbert L 2013 Environmental determinants of Ixodes ricinus ticks and the incidence of Borrelia burgdorferi sensu lato, the agent of Lyme borreliosis in Scotland. Parasitology 140(2): 237-46


seasonal prevalence with peaks in spring and autumn. Te ticks have a two-year life cycle. Te growing interest in countryside pursuits such


as walking and camping may have increased the prevalence of Lyme borreliosis in humans. Occupational groups including forestry, estate, ecologists and outdoor instructors are at particular risk of infection. Prevention of tick bites is the best way of avoiding


Lyme borreliosis and an important public health message. Walkers should be encouraged to stick to paths and dress well-covered to prevent access to skin (e.g. trousers tucked into socks). Both children and adults should be checked for ticks aſter outdoor activities, especially in the hair and behind the knees. Ticks should be removed promptly with a special plastic removal tool and not with fingernails or ordinary tweezers. Tick bites do not always result in borreliosis: at


worst only 10 per cent of ticks are affected. Proper and prompt removal effectively eliminates the chance of Lyme borreliosis.


Presentation and early management A rash on the legs or arms aſter exposure to ticks may be erythema migrans. Urban GPs need to consider late Lyme borreliosis in people with neurological or joint symptoms having returned from UK or other Northern European hotspots. Around 70 per cent of patients will give a clear history of tick bite and rash. Te classic bull’s-eye rash of erythema migrans


can be seen but this will evolve over days to coalesce into a red area around the tick bite site and may persist or begin to fade. Te patient may be unable to adequately see their rash behind the knees or in skin folds. Allergic reactions to flying insect bites will usually be raised in contrast to erythema migrans. Lyme serology is unhelpful in diagnosing erythema migrans which is an entirely clinical diagnosis.2 Antibiotics should not be prescribed


prophylactically for a simple tick bite. However, give 2-4 week courses of doxycycline 100mg bd when the diagnosis is erythema migrans. Patients should be encouraged to take photographs of their rash and


SUMMONS


Page 1  |  Page 2  |  Page 3  |  Page 4  |  Page 5  |  Page 6  |  Page 7  |  Page 8  |  Page 9  |  Page 10  |  Page 11  |  Page 12  |  Page 13  |  Page 14  |  Page 15  |  Page 16  |  Page 17  |  Page 18  |  Page 19  |  Page 20  |  Page 21  |  Page 22  |  Page 23  |  Page 24