Download Lyme borreliosis in Wales 1990 - 2004

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.
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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
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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
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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
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