The theme of the World Health Day in April 2014 was vector-borne diseases- 'Small Bite: Big Threat'. For many people this conjured up thoughts of Malaria, Dengue or West Nile Virus but, few people in the UK are aware that the UK's most common vector-borne human infection is Lyme disease.[i]

Although Lyme disease in endemic in the UK few people actually know what it is. Caught early and treated with antibiotics, years of debilitating health problems can be prevented. Yet, many general practitioners (GPs) lack knowledge of the disease and the recommended diagnostic tests lack the sensitivity and specificity to detect early cases or late manifestations of the disease, such as chronic or autoimmune-related infections. As a result the incidence of the disease is seriously underestimated with many cases going undiagnosed or misdiagnosed.

Lyme disease is an infection caused by a family of genetically diverse bacteria called Borrelia burgdorferi. The bacteria are transmitted to humans by ticks, small spider-like insects which live in long grass, woods, and other damp vegetation where they feed on the blood of deer and other mammals. Much like the organism that causes Malaria, the bacteria take different forms throughout their lifecycle, which makes them difficult to detect and leads to a diverse range of symptoms. Symptoms are initially mild and limited to the locality of the bite, but if left untreated chronic Lyme disease often develops which can have devastating, long term effects.

Patients treated with appropriate antibiotics in the early stages of Lyme disease usually recover rapidly and completely. Nevertheless, one of the greatest barriers to effective, early treatment remains GPs lack of awareness of the complexity of the disease, or the diverse symptoms with which patients may present. As a result, too many patients suffer the long-term or chronic impact of Lyme disease and are misdiagnosed with multiple sclerosis, chronic fatigue syndrome and arthritis.

The incidence of Lyme borreliosis has been monitored in England and Wales by the Health Protection Agency (HPA), now part of Public Health England (PHE), since 1996. Since 2010, every microbiology laboratory (including those in the private sector) in England is required to notify all laboratory diagnoses of borreliosis to the Health Protection Agency (now Public Health England). Laboratory-confirmed reports of Lyme disease have risen steadily since surveillance began. In 2011 there were 959 confirmed cases and in 2012, 998[ii]. In acknowledging the significant difficulties in diagnosing Lyme disease, PHE suggest the truer figure is likely to be around 2,000 - 3,000 new cases each year. However, Lyme disease patient groups believe the number to be closer to 15,000 cases a year.[iii]

Factors that may have contributed to the increase include the geographical migration of ticks as a result of successive mild winters, an explosion in the deer population and increased recreational travel to high endemic areas, including walking, trekking, and mountain biking in the UK and abroad.

There are a number of significant challenges in diagnosing Lyme disease:

  • patients may not be aware that they have been infected as ticks are typically invisible to the naked eye and inject a local anaesthetic-like substance so bite goes unnoticed (the longer the tick is in place, the higher the risk of infection)
  • Lyme disease is difficult for GPs to diagnose as the most common, and in some cases only manifestation is erythema migrans (known as the'bull's eye' rash) which appears between three and 30 days after a bite. However around 30 to 40 per cent of patients do not present with a rash (not the 90 per cent cited on the NHS website[iv]), but present with a range of non-specific 'flu-like symptoms, tiredness, headaches, arthralgia (joint pains) and myalgia (muscle aches). Even where there is a rash, this varies in appearance and size (from two to 30 centimeters), expanding over several days or weeks
  • there is no definitive laboratory test for Lyme disease. Since June 2012, the Lyme disease testing service in the UK has been carried out by the Rare and Imported Pathogens Laboratory (RIPL) in Porton Down using a two-tier testing system recommended by American and European authorities comprising: the C6 antigen based enzyme linked immunosorbent assay (ELISA) test; followed by the immuno-blotting (western blotting) test. If the results of both the ELISA test and the Western Blot test are positive, a confident diagnosis of Lyme disease can usually be made.[v]

The manufacturers of both the ELISA and Western Blot tests, however, clearly state that a negative result should NOT be taken as meaning you don't have Lyme disease. Indeed if an initial test is negative, but symptoms persist, there should be a repeat sample 3-4 weeks after the initial test. 

In 2013, PHE launched a series of leaflets to raise awareness of Lyme disease and other tick-borne illnesses among health professionals and the public[vi] and in May this year issued guidelines for referral pathways for patients suspected of having Lyme disease[vii]. This guidance clarifies that the significance of any result, negative or positive, should be interpreted carefully by clinicians in the overall context of the patient's clinical symptoms and exposure risk to ticks. Specifically, patients seen by a GP with an Erythema migrans rash at the time of consultation should be treated with antibiotics indicated for Lyme disease; while patients without a rash but with symptoms suggestive of Lyme disease, and a credible risk of tick exposure, should have serum taken and sent to an NHS laboratory for testing. 

For patients there is currently no vaccine available to prevent Lyme disease. Meanwhile, clinicians have to interpret symptoms which may not match the "classic symptoms" of Lyme and rely on tests which lack sensitivity and specificity. As a result there is some way to go before Lyme's disease can be diagnosed and treated effectively. Work is on-going to equip the GP community to diagnose better and instigate earlier treatment. However, in the absence of an accurate diagnostic test, raising public awareness about risks and prevention and how to identify symptoms early is key if we are to reduce the debilitating effects of this relatively rare, but potentially devastating disease.

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