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Lyme borreliosis in Wales 1990 - 2004 This report is on occurrence of serologically confirmed Lyme borreliosis in Welsh residents during the period 1990 to 2004. Lyme borreliosis (Lyme disease) is an infection caused by Borrelia burgdorferi, spiral bacteria that are transmitted by bites from infected ticks of the Ixodes ricinus complex. It is acquired in temperate regions of the northern hemisphere, usually in forested, woodland or heathland areas which support the life-cycles of ticks and the small mammals and birds that are borrelial reservoir hosts. Several pathogenic genospecies of B. burgdorferi have been identified, and there is some evidence for variation in types of clinical presentations caused by the different genospecies. The earliest, most common and sometimes the only manifestation of Lyme borreliosis is erythema migrans which may appear between 3 and 30 days following a tick bite. Some patients also have rather non-specific “flu-like” symptoms with tiredness, headaches, arthralgia or myalgia. Neuroborreliosis is the most common complication of Lyme borreliosis in the UK, chronic neuroborreliosis is however rare and probably caused by direct infection of the nervous system. Lyme arthritis is rare in patients with UK-acquired infection and more common when the disease is acquired in Europe or North America. A small proportion of patients who may have been appropriately treated may go on to develop a post-infection syndrome (post Lyme syndrome) resembling chronic fatigue syndrome or fibromyalgia. Similar symptoms can however be triggered by other infectious and non-infectious conditions. Serological diagnosis in England and Wales follows an internationally recommended two-step approach using commonly available antibody screening tests, followed by immunoblotting or reactive or equivocal samples to assess the specificity of reactions. The number of serologically confirmed reports in England and Wales has continued to rise in recent years. Epidemiology of Lyme borreliosis in Wales Forty one reports of Lyme borreliosis were received from laboratories in Wales during the period (Table 1., Figure 1). Figure 1. Lyme borreliosis in Wales 1990 - 2004 10 8 6 4 2 0 1990 1992 1994 1996 1998 2000 2002 2004 Lyme borreliosis is not notifiable under public health legislation in England and Wales, it is however notifiable under health and safety legislation (RIDDOR 95) to the Health and Safety Executive (HSE) when acquired as a result of “Work involving exposure to ticks…”. Twenty one reports were made on CoSurv by laboratories in Wales, 20 reports were received directly from the HPA Lyme Diagnostic Unit (LDU) in Southampton. All the reports made on CoSurv were also reported to the England and Wales Zoonoses Surveillance Unit at CDSC Wales (ICDS, NPHS) by the LDU in Southampton. The number of cases reported to HSE remains low. 1 Table 1. Year 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 Number 2 0 0 1 1 1 2 2 7 0 0 5 10 3 7 Age and sex distribution of cases The sex distribution of cases reported in Wales (F;M; 0.78 : 1.0) is similar to that seen in the national picture where an approximately equal male to female ratio has been reported. This distribution reflects the largely recreational sources of infection commonly reported with this disease. Any dissimilarity between the England and Wales figures are probably due to the low number of cases reported from Wales. Reports were received from patients in all age groups: Table 2. Agegroup Number (%) Wales England & Wales 1990-2004 2004 01 - 14 5 (12) 12% 15 - 24 3 (7) 5% 25 - 39 10 (24) 16% 40 - 64 13 (32) 49% > 65 6 (15) 15% Not stated 4 (10) 2% Sources of Lyme borreliosis Not all infections were acquired in Wales; 15 (37%) patients reported overseas travel as the likely source of infection; most acquired their infection in northern European countries or in the United States; Germany (4), France (3), Italy (1), Denmark (1) United States (6). Included in these figures are one patient who was a New Jersey resident on holiday in the UK, one who was resident in Denmark and a German national who became infected in, and was initially diagnosed in Germany. Three patients reported travel within the UK as a likely source of infection (Lake District, Scotland and north-east Wales to north-west Wales); one patient experienced tick bites as a resident of rural north Wales and one patient, a forestry worker in the Dolgellau area, had frequent exposures to deer and also experienced frequent tick bites. A report of Lyme borreliosis acquired on the Brecon Beacons during the Foot and Mouth disease cull by a member of the armed forces is not included in this report as he was resident in the South West Health Region of England. Similarly, this report does not include patients from elsewhere in the UK who identified travel to Wales as a possible source of their infection. Clinical presentations No clinical details other than a report of erythema migrans in 23 cases, were reported for 30 patients. Amongst those patients reporting symptoms, some would have presented with more than one. Twenty three patients reported tick bites or tick exposures. Arthritis was reported in two 2 patients both of whom received tick bites overseas (Italy and Forests in Northern Germany). Five patients reported arthralgia and/or myalgia. Two patients reported facial palsies (bilateral in one case, and radiculopathy was identified in another patient). Headache, flu-like illness and other non-specific symptoms were also reported by six patients. Information is seldom provided on the nature of any treatment given to the patient. Temporal trend Fifty one percent of all cases had first specimen dates (as a proxy for date of exposure or onset which are frequently unknown) in the months of July, August and September with 27% of reports occurring in the first 6 months of the year and 22% in the final quarter. Table 3. Month (’90 -’04) 1 2 3 4 5 6 7 8 9 10 11 12 Reports 2 0 2 0 2 5 6 9 6 4 3 2 Lyme borreliosis in children Reports of Lyme borreliosis were received for 5 children under 15 years of age during the period; in a further case reported in a 16 year old female it is likely that she acquired her infection when aged about 13, whilst the family were resident in northern Germany. Of the 5 children under 15 years at the time of report, four were known to have acquired their infections overseas USA (2), Denmark (1), Germany (1) and in one case there was no history. One of the US cases was a New Jersey resident on holiday in the UK and the case from Denmark was in a Danish resident. Discussion The number of reports of Lyme borreliosis arising from exposures in Wales remains low although in England and Wales taken as a single unit, serologically confirmed cases have continued to rise since the introduction of enhanced surveillance in 1996/1997. Whilst this may represent in part, a true increase in incidence, the role of enhanced surveillance cannot be discounted. Forty one percent of reports submitted by laboratories in Wales were for infections acquired elsewhere, predominantly overseas, this is slightly above the proportion of overseas acquired infections (c. 25%) reported for England and Wales as a whole. Despite appropriate tick habitats being present throughout Wales, the number of infections remains low. The reports listed here are made up of voluntary submissions by microbiologists in Welsh laboratories (50%) and reports received directly from the HPA Lyme Diagnostic Unit in Southampton (50%), however neither include patients with early Lyme borreliosis diagnosed and treated and in which microbiological confirmation is not sought; these cases are not recorded elsewhere. Climatic factors such as drought or prolonged cold weather can affect tick populations and activity significantly, which may also affect the incidence of Lyme borreliosis from year to year. Throughout Europe, heterogenous deciduous woodlands appear to provide particularly favourable ecological conditions for the host species that maintain both ticks and spirochaetes. Changing ecological and environmental conditions including altered patterns of land utilisation may also affect tick populations and those of animals which act as borrelial hosts. There is strong evidence to show that both the prevalence of B. burgdorferi infected ticks and the 3 incidence of Lyme borreliosis in Europe in highest in eastern countries and decreases westward across the continent, including the British Isles. There is no vaccine currently available in Europe: a vaccine was available in the USA but was withdrawn in 2002; it was unlikely to have been effective against European borrelial genospecies. Further reading Association of Medical Microbiologists (AMM) http://www.amm.co.uk/newamm/files/factsabout/fa_lyme.htm Centers for Disease Control and Prevention: www.cdc.gov/ncidod/dvbid/lyme/index.htm European Concerted Action on Lyme Borreliosis EUCALB (European Concerted Action of Lyme Borreliosis) http://www.oeghmp.at/eucalb/ Health Protection Agency: www.hpa.org.uk/infections/topics_az/zoonoses/lyme_borreliosis/menu.htm Smith RMM, O’Connell S, Palmer SR. Lyme Disease Surveillance in England and Wales. Emerging Infectious Diseases 2000; 6 (4): 404-07. http://www.cdc.gov/ncidod/eid/vol6no4/smith.htm). Sood,S K. Effective retrieval of Lyme disease information on the Web. Clinical Infectious Diseases 2002; 35:451-464 http://www.journals.uchicago.edu/CID/journal/issues/v35n4/020270/020270.html Wormser GP, Nadelman RB, Dattwyler RJ, et al. Practice Guidelines for the treatment of Lyme Disease. Clin Infect Dis 2000; 31 (suppl): S1-S14. http://www.journals.uchicago.edu/CID/journal/issues/v31nS1/000342/000342.html 4