An overview of Borreliosis in the UK and Ireland

Although Borreliosis is often described as rare in the UK and Ireland, it may not be as rare as most people think. It has existed for centuries, though not under its modern names (Borreliosis, Lyme disease or Lyme borreliosis). There are several reasons why it may be ignored, dismissed and under recorded:

Diagnostic problems

Borreliosis is difficult to diagnose because it produces a bewildering variety of signs and symptoms, most of which resemble those of other diseases. This can lead to misdiagnosis. Its only specific sign is an Erythema Migrans (EM) rash, which occurs in fewer than 50% of patients. Of the 813 laboratory-confirmed cases of Borreliosis in England and Wales in 2008, only 32% had a documented EM rash (similar to the previous year). Rashes can go undetected if they appear in inaccessible places or they are hidden under thick body hair or hair on the scalp. They can also present in an atypical form instead of the classic “bull’s eye” which is so often depicted in medical journals.

The patient may not recall a tick bite. Of the 813 laboratory-confirmed cases of Borreliosis in England and Wales in 2008, only 40% had a documented tick bite (similar to the previous year).

There is no single 100% reliable test for Lyme disease. In Ireland, physicians have access to the National Virus Reference Laboratory which performs serological tests for Borreliosis. The NHS in the UK currently uses a two-tier testing procedure; firstly an ELISA (Enzyme-Linked Immunosorbent Assay), which is followed (but only if equivocal or positive) by a Western blot or ‘immunoblot’. However, both in the UK and Ireland, these tests rely on the presence of antibodies which may take some weeks to develop after the patient has become infected. In certain cases, a patient with a more established infection may be sero-negative (infected without the presence of antibodies). This is more likely to occur in patients who have received insufficient antibiotic treatment early in the course of the disease, or if they are on certain other types of medication, such as steroids, which can interrupt the antibody response. In such cases, the patient's blood sample can return a false-negative result and further testing may show sero-conversion (the appearance of antibodies where previously there had been none) when they are re-tested at a later date.

Conversely, a patient's blood sample may return a false-positive result if they have previously had an unrecognised or asymptomatic infection but are not currently infected. This can occur in people who are occupationally or recreationally exposed to regular tick bites. False reactions during testing can also occur in people who have been affected by other conditions, such as glandular fever, syphilis, rheumatoid arthritis, other autoimmune conditions and some neurological conditions.

The significance of any result, negative or positive, should be interpreted carefully by clinicians in the overall context of the patient’s clinical and tick-exposure risk history.

Disease prevalence

In England and Wales Borreliosis is not a notifiable disease. Cases are recorded through a enhanced voluntary surveillance scheme where the Health Protection Agency's Lyme Borreliosis Unit (LBU) reports all laboratory-confirmed cases directly to the Zoonoses Surveillance Unit at the National Public Health Service (NPHS), Wales. However, the Health Protection Agency states that, "Reporting levels have improved, but the data remain incomplete because they do not include cases diagnosed and treated on the basis of clinical features such as erythema migrans (the early rash of Lyme borreliosis), without laboratory tests. It is estimated that between 1,000 and 2,000 additional cases of LB occur each year in England and Wales".

In Scotland, Lyme disease is a notifiable condition but many doctors appear not to be aware of this and so cases can go un-recorded. Some doctors consider the yearly statistics to be seriously underestimated, owing to cases that are not reported, patients that are misdiagnosed with other conditions, and asymptomatic carriers of the disease.

In Ireland, Borreliosis is not a notifiable condition, nor is there an enhanced voluntary surveillance scheme. In 2007, 71 specimens, referred to the UK Health Protection Agency’s Lyme Borreliosis Unit from Irish hospital laboratories, were confirmed positive for Lyme borreliosis, suggesting a crude incidence rate of 1.67 per 100,000 for Lyme borreliosis in Ireland that year. However, the Health Protection Surveillance Centre (HPSC), Ireland, considers that the incidence may be much higher. They state that, "When there is not the legal onus on practitioners to report cases of an infectious disease, the knowledge we have about such disease is, accordingly, incomplete. Notification allows identification in a more systematic way, and facilitates following trends in the disease over time".

An increasing threat

Cases of tick-borne disease have increased due to a number of probable factors:

1. Warmer winters and moist summers allow more ticks to survive and to complete their life-cycle more quickly;


2. An increase in certain species of animals, which are favoured by ticks as hosts, can act as an increased reservoir for disease and better support the tick population;


3. A reduction in sheep-dipping, motivated by concerns over the carcinogenic effects of the active ingredients on human health, and cost implications for farmers, has reduced effective control of ticks;


4. A greater number of people are involved in outdoor recreational activities and are spending more regular and prolonged periods in tick habitat.

Other potential contributors to the spread of Borreliosis and other tick-borne diseases are:

1. An increased frequency of foreign travel, not only by people but now also by their pets, which have the potential to import infected ticks. The Pet Travel Scheme (PETS) requires pets to be treated for ticks not less than 24 hours, and not more than 48 hours, before checking in with an approved transport company, but animals are still reported to be entering the UK carrying infected ticks;


2. Pets travelling abroad can be exposed to diseases which may then be transmitted to British ticks once the animals have returned to the UK.

A cocktail of infections

The "sheep tick" or "wood tick", Ixodes ricinus, can infect livestock (and sometimes humans) with the Louping- ill virus. It can also carry Borreliosis, along with co-infections such as Anaplasmosis, Babesiosis, and possibly Bartonellosis. These co-infections can make the diagnosis and treatment of Borreliosis patients more problematic. Unfortunately Ixodes ricinus has a varied taste for prey, including birds, reptiles, livestock, many small mammals such as rats, hedgehogs and squirrels, and also human beings. Because many tick-host species are freely mobile, they can drop infected ticks in other areas (sometimes across oceans) or act as reservoirs of infection, ready to pass on pathogens to local ticks, thus spreading the disease.

Urban ticks

It is commonly supposed that one can only be bitten by ticks in such places as meadows and woodland, and then only in acknowledged "hot spots", such as the New Forest or the Highlands of Scotland. However, tick sampling by scientists has shown that ticks infected with Borrelia bacteria can be found in many areas, including the London parks. A case of urban-acquired Borreliosis would often be overlooked by doctors simply because the patient didn't report a countryside visit in an acknowledged "hot spot".

Urban Borreliosis is an issue that is little considered but could have serious implications for many people, including the homeless, who frequently sleep in parks and cemeteries. Birds, hedgehogs and squirrels, domestic dogs and cats, can all carry ticks and all visit urban gardens. DEFRA (Department for Environment, Food, and Rural Affairs) describes Borrelia and Bartonella bacteria to be endemic to UK dogs and cats.

Rats and mice too are possible reservoirs for these diseases, and they can infest buildings as well as parks and gardens. The National Pest Technicians Association's annual survey revealed a marked increase in both rat and mouse problems across the United Kingdom in 2007/8, with over 90% of pest control professionals reporting higher levels of rat activity in recent years, and just under 80% greater mouse activity.

Pigeon colonies on buildings (such as King's College, Cambridge) have been demonstrated to be a haven for Argas reflexus, a soft tick which will readily attach to humans, and which is known to be a potential carrier of Borreliosis. The World Health Organisation has highlighted urban sprawl as an increasing contributor to the spread of zoonotic diseases, including Borreliosis.

Awareness is essential

It is important for residents of the UK and Ireland to become more aware of these facts, to take sensible precautions against tick bites, to learn how to remove an attached tick without increasing their own risk of infection, to recognise infection in themselves and others and to access prompt diagnosis and treatment if infection is suspected.

Passing on this information to family, friends and colleagues will also dramatically increase the level of awareness which, in turn, will help combat the rise in incidence of tick-borne disease. Simple and informative leaflets are available from BADA-UK.