Lyme disease - Lyme borreliosis: Europe-wide coordinated surveillance and action needed?

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http://www.eurosurveillance.org/ew/2006/060622.asp#1

Lyme borreliosis: Europe-wide coordinated surveillance and action
needed?

R Smith1, J Takkinen2, Editorial team3
(eurosurveillance.weekly@hpa.org.uk)

1National Public Health Service for Wales, Cardiff, Wales, United
Kingdom
2European Centre for Disease Prevention and Control, Stockholm, Sweden
3Eurosurveillance editorial office

Lyme borreliosis (Lyme disease) is an infection caused by the
spirochete
bacteria Borrelia burgdorferi sensu lato, which are transmitted by
bites
from infected ticks of the Ixodes genus (mainly Ixodes ricinus in
Europe). Lyme borreliosis is the most prevalent arthropod-transmitted
human infection in northern Europe, North America and temperate Asia.
In
Europe, ticks are usually found in mixed deciduous woodland or moorland

areas where the microclimate supports their life cycles, and there are
small mammals and birds serving as hosts. Four genospecies (B.
burgdorferi sensu stricto, B. afzelii, B. garinii and possibly B.
valaisiana) cause Lyme borreliosis and all have been detected in
Europe.
There is evidence for varying clinical presentations of Lyme
borreliosis
caused by these different genospecies [1].

Like syphilis, Lyme borreliosis is a multisystem infection, which has
several stages and symptoms that mimic other infections. After an
initial infection, which is localised to the site of the tick bite, and

commonly characterised by an red rash expanding around the area of the
tick bite (erythema migrans), the bacteria may spread to other sites in

the body. Some patients also have non-specific influenza-like symptoms,

such as tiredness, headaches, and aches and pains in the muscles and
joints. Secondary sites of infection may include the nervous system,
joints and heart and may lead to severe neurological complications
(neuroborreliosis) and chronic arthritis [2]. Early detection of
erythema migrans is crucial, as the disease is easily treated with
antibiotics at this stage, preventing the development of later, more
severe stages of the disease.

Detection and reporting of Lyme borreliosis
Characteristic clinical signs of Lyme borreliosis such as erythema
migrans, if present, are a good indicator of the disease. Diagnosis
takes into account the risk of tick exposure. Supporting evidence is
provided by laboratory investigation, usually antibody tests.

Although this infection is most commonly diagnosed during the summer,
coinciding with greatest tick activity, cases are reported throughout
the year, probably because unspecific symptoms cause delays in both
consultation and diagnoses, and also because of the long incubation
period of some clinical manifestations. Different case definitions are
in use throughout Europe. Misdiagnosis (mainly overdiagnosis) can occur

because clinical presentations are not unique to Lyme borreliosis
[2].The European Concerted Action on Lyme Borreliosis network (EUCALB,
http://www.oeghmp.at/eucalb/) has published a consensus case definition
[3].

Problems with comparing data in Europe
Approaches to collecting data on the incidence of Lyme borreliosis vary

considerably across Europe. Very few countries have made Lyme
borreliosis a mandatorily notifiable disease, and there are currently
no
plans to add this to the listed diseases covered by European
Community-coordinated disease surveillance [4].

In the majority of countries, data is collected mainly through
diagnostic laboratories reporting available details of patients with
positive test results. Drawbacks of laboratory data include
under-reporting of erythema migrans, varying patterns of test
referrals,
varying criteria for serological diagnoses and inclusion of
seropositivity which may be due to past infection. Other sources of
incidence estimates include voluntary reporting, GP/physician surveys,
and hospital in- and out-patient diagnoses. Differences in data sources

used, and in biases in those sources, make it difficult to draw
meaningful comparisons between countries. At present national
surveillance systems and routine diagnostic reporting is probably the
best way of obtaining epidemiological data throughout Europe; however,
this should be complemented by specific human seroprevalence studies.

Based on available data, the highest reported incidence of Lyme
borreliosis is found in central Europe, with an estimated incidence of
206 per 100 000 population in Slovenia (based on laboratory reports)
and
135 per 100 000 population in Austria (based on physician surveys)
(Table). In southern Europe, incidence appears to be much lower, with
an
incidence of less than 1 per 100,000 (fewer than 30 cases per year) in
Portugal and Italy. However, focal areas of higher incidence can occur
in countries where the incidence is generally low.

Table. Reported cases or estimated cases and incidence by European
country, source Eurosurveillance Editorial Advisors and others.
large variation in methods used to acquire data in different European
countries

Trends in incidence of Lyme borreliosis
The data presented here, and also the results of some other studies,
indicate that the incidence of Lyme borreliosis may be increasing in
certain European countries, assuming that surveillance systems have
been
stable [6]. Nine of 16 European countries with time-series data
available (Table) show evidence of increasing incidence of Lyme
borreliosis, although these data are only for a relatively short time
period of five years, and may not reflect the longer term trend.
Increases have been seen in Poland, eastern Germany, Slovenia,
Bulgaria,
Norway, Finland, Belgium, Britain (England & Wales and Scotland) and
the
Netherlands. The fairly large increase that occurred between 2003 and
2004 was 44% in Belgium, 74% in Norway, 51% in Finland, and 73% in
Bulgaria.

Tick numbers and activity levels affect the number of cases of Lyme
borreliosis. The prevalence of ticks infected with B. burgdorferi and
the incidence of Lyme borreliosis is higher in central and eastern
Europe and lower in western Europe. Changes in human behaviour (in some

European countries this may include visiting summer houses, hiking,
mushroom or berry picking, hunting or fishing) and the ecology of tick
hosts (eg, increase in populations of animals such as deer) may affect
exposure of humans to ticks. Climate change, resulting in milder
winters
and thus more ticks, is also hypothesised to contribute to increasing
Lyme borreliosis [7]. At the same time, increased awareness of ticks as

vectors, and increasing interest in Lyme disease have undoubtedly
stimulated protective measures and surveillance [8]. A number of other
infections can also be transmitted through the bite of a hard-bodied
(ixodid) tick, including ehrlichiosis, babesiosis, bartonellosis,
tickborne encephalitis, tularemia and possibly Q fever. Changes in the
density and geographic distribution of ticks may eventually be
reflected
in changes in the incidence of both Lyme borreliosis and other
tickborne
infections in some European countries.

Tick bite avoidance is currently the most effective prevention
There is currently no vaccine for Lyme borreliosis. Effective
prevention
relies on increased public education about the disease and avoidance of

tick bites (eg, using protective clothing, insect repellents, and early

detection and removal of ticks).

Workers in high-risk occupations, such as farming and forestry, and
long-term residents of highly-endemic areas are likely to recognise
ticks and to have some awareness of the symptoms of Lyme disease.
Visitors from cities and non- or low endemic regions (for example, on
activity holidays, walking, trekking and mountain biking in these
areas)
often have little or no knowledge of ticks and the disease. Physicians
from these areas may be relatively unfamiliar with, and unsuspecting
of,
the disease. Such people may therefore be vulnerable to both infection
and to under-diagnosis and development of disseminated or chronic
infection after returning home.

Footnote
Websites recommended by the European Union Concerted Action on Lyme
Borreliosis network (EUCALB) for public and/or professional information
are:

· American College of Physicians Online. Initiative on Lyme disease.
http://www.acponline.org/lyme/
· United States Centers for Disease Prevention and Control. Learn
about
Lyme disease. http://www.cdc.gov/ncidod/dvbid/lyme/index.htm
· National Reference Laboratory for Borreliae, Munich University.
Lyme
borreliosis.
http://pollux.mpk.med.uni-muenchen.de/alpha1/nrz-borrelia/miq-lyme/frame-summary.html

Acknowledgements:
With particular thanks to Professor Jeremy Gray at EUCALB, Dr Reinhard
Kaiser, Ms Agnetha Hofhuis, Dr Sarah Randolph, Dr Robert Hemmer, Dr
Bohumir Kriz, Dr Irina Lucenko, Dr Paula Vasconcelos, Dr Mira
Kojouharova, Dr Stefania Salmaso, Dr Rasa Liausediene, Dr Tanya Melillo

Fenech, Dr Alenka Kraigher, , Dr Reinhild Strauss, Dr Germaine Hanquet,

Dr Koen de Schrijver, Dr Ines Steffens, Dr Malgorzata Sadkowska, Dr
Judite Catarino, Mr Norman MacDonald, Dr Lelia Thornton, Dr Chryso
Gregoriadou, Dr Olga Kalakouta, Dr Markku Kuusi, Ms Aase Sten, Dr Eva
Maderova, Dr Hilde Kløvstad, Dr Maria Grazia Pompa, Dr G Stanek

References:

1. Derdakova M, Lencakova D. Association of genetic variability within
the Borrelia Burgdorferi sensu lato witht the ecology, and epidemiology

of Lyme borreliosis in Europe. Ann Agric Environ Med 2005; 12: 165-72
2. European Concerted Action on Lyme Borreliosis. Website.
(http://www.oeghmp.at/eucalb/)
3. Stanek G, O'Connell S, Cimmino M, Aberer E, Kristoferitsch W,
Granström M, et al. European Union Concerted Action on Risk Assessment

in Lyme Borreliosis - Clinical Case Definitions for Lyme Borreliosis.
Wien.Klin.Wochenschr 1996; 108: 741-747, see also EUCALB website
(http://www.oeghmp.at/eucalb/diagnosis_case-definition-outline.html)
4. COMMISSION DECISION of 22 December 1999 on the communicable diseases

to be progressively covered by the Community network under Decision No
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7. Lindgren, E. & Jaenson, T.G.T. 2006. Lyme borreliosis in Europe:
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