Lyme disease

The risk of exposure to Lyme disease is greatest in late spring and early summer, so now is the time to ensure that we and our patients are aware of the risks posed by tick bites.

Pharmacists have an important role in preventing and treating Lyme disease through:

• Provision of patient education in relation to reducing the risk of a tick bite;
• Providing advice and information on the importance of prompt tick removal;
• Recognising the signs and symptoms of Lyme disease;
• Promoting the timely use of appropriate antibiotic therapy (optimal drug choice, dose and duration) for the treatment of Lyme disease as per the HSE national antibiotic prescribing guidelines on www.antibioticprescribing.ie.

Introduction

Lyme disease (also known as Lyme borreliosis) is an infection caused by Borrelia bacteria. It is transmitted to humans through the bite of a tick infected with Borrelia bacteria. Infected ticks are active from spring to autumn and this is when we expect to see cases of Lyme disease most frequently in Ireland.

Lyme disease can be prevented with early identification and removal of ticks. If symptoms of Lyme disease are identified early, there is a high cure rate with optimal antibiotic treatment.

Lyme disease can affect anyone but is most common among hill-walkers, hikers, campers and others whose leisure activities or work takes place in tick habitats or those who are in contact with certain animals e.g. deer and sheep. Ticks can be found in both urban and rural environments but are most likely to be found in the following areas:

• Shady and humid woodland clearings with grass;
• Open grassland, parkland, fields and bushes;
• Walking paths, especially those bordered by long grasses;
• Wooded and forested areas;
• Vegetation close to lakes and seaside beaches.

Erythema migrans versus bite reaction

Figure A: Image of Erythema Migrans Typical ‘bulls-eye’ rash	Figure B: Image of a bite reaction
Not usually itchy or painful; Flat, red macule or papule at bite site; May appear from 3 days to 30 days after tick bite and lasts for weeks.	Usually hot, itchy and painful; Often raised papule, central punctum; and Usually develops and recedes within 48 hours.

Recognising Lyme disease

The first stage of Lyme disease may present as a skin rash and/or flu-like symptoms. The most common noticeable evidence of early infection is an expanding red rash with a central clearing at the site of the tick bite (known as erythema migrans or a ‘bulls-eye’ rash – see figure A)). It usually develops between three days and a month after a tick bite and lasts for several weeks. Not everyone with Lyme infection develops a rash and this ‘bulls-eye’ pattern is only present in some cases. The rash occurs in about 60% of patients (less frequently in children). It is important to be aware that a rash (that is not erythema migrans) can develop as a reaction to a tick bite. This rash (see figure B) usually develops and recedes within 48 hours from the time of the tick bite.

Advice to reduce the risk of being bitten by a tick:

1. Cover skin while walking outdoors and tuck trousers into socks
2. Use insect repellent on clothes and skin – products containing DEET are best
3. Stick to paths whenever possible
4. Wear light-coloured clothing so ticks are easier to spot and brush off

Ticks tend to attach and feed on the legs (50% of all bites) and arms (20% of all bites) of adults. Less commonly they bite on the torso, head, neck and groin. This highlights the importance of keeping arms and legs covered and checking these areas after returning from typical tick habitats. In children, ticks most commonly bite the head region, around the hairline (40%) and around the neck (40%). These would be the most important areas to check on a child.

Patients may also complain of influenza-like symptoms such as headache, sore throat, neck stiffness, fever, muscle aches and general fatigue. Occasionally, there may be more serious symptoms involving the nervous system, joints, the heart or other tissues. These complicated infections generally require referral to specialist services. Although severe disease is rare, it most frequently arises due to previously unrecognised early Lyme disease or inadequate initial treatment.

Preventing Lyme disease

The single most important measure that will prevent Lyme disease is the prevention of transmission of the bacteria from an infected tick to a person and this involves either:

1. Preventing ticks biting in the first place or
2. If a person has been bitten, the removal of any ticks at the earliest opportunity

Only a small number of ticks are infected with the bacteria that cause Lyme disease and therefore tick bites do not always result in a person becoming infected. The longer the tick has been attached to the skin, the greater the chance of being infected. There is compelling evidence to suggest that if a tick is removed as soon as it bites or in the hours following a bite, the risk of infection will be low. This is why it is important that a person checks themselves, family and pets for attached ticks immediately following exposure to typical tick habitats.

If a tick bite is identified, Lyme disease can be prevented with appropriate antibiotic post-exposure prophylaxis, however antibiotics are not always warranted. Think of the 36-hour timeframe: If the tick has been attached for less than 36 hours, the risk of Lyme disease is very low and antibiotics are not recommended. If it is unknown how long the tick has been attached or if it has been attached for greater than 36 hours, a single dose of doxycycline can be offered as post-exposure prophylaxis.

There is currently no evidence available to support the use of alternate prophylactic antibiotics for Lyme disease. As the risk of infection is low and Lyme disease is readily treatable once symptoms develop, watchful waiting in the case of contraindication to doxycycline is recommended instead of antibiotic prophylaxis.

Treating Lyme disease

Appropriate antibiotics minimise the likelihood of the development of late stage infection and long term complications of Lyme disease. All patients with symptoms of Lyme disease, including erythema migrans (‘bulls-eye’ skin rash) should be treated with an appropriate course of antibiotics. The HSE national antibiotic guidelines for Lyme disease are available for pharmacists to access for further guidance on the recommended antibiotic choice, dose and duration of treatment (www.antibioticprescribing.ie).

Some people who are diagnosed and treated for Lyme disease continue to have symptoms such as tiredness, aches and loss of energy that can last for years. Antibiotics are not recommended where Lyme disease has previously been adequately treated as there is no demonstrable clinical benefit from prolonged antibiotic therapy and the risk of harm outweighs the benefit. In this case, supportive management can be offered (e.g. management of chronic pain, fatigue, depression, sleep disturbance) and specialist advice sought if necessary.

“Lyme disease can be avoided by not getting tick bites or by removing ticks as soon as possible.”  

References available upon request.

All images courtesy of antibioticprescribing.ie

References: (not for publication)

1. Health Service Executive 2021, Lyme disease. [online] Available at https://www.hse.ie/eng/services/list/2/gp/antibiotic-prescribing/conditions-and-treatments/skin-soft-tissue/lyme-disease/lyme-disease.html. [accessed 22 April 2022]
2. Clinical Practice Guidelines by the Infectious Diseases Society of America (IDSA), American Academy of Neurology (AAN), and American College of Rheumatology (ACR): 2020 Guidelines for the Prevention, Diagnosis and Treatment of Lyme Disease. Published 30/11/20.
3. Red Book (2018): Report of the Committee on Infectious Diseases, 31st Edition. The Committee on Infectious Diseases of the American Academy of Paediatrics.
4. McKeown P. May 2022. ‘Lyme disease: Raising Awareness’. Epi-Insight. The Health Service Executive – The Health Protection Surveillance Centre. Volume 23. Issue 3.