To test or not to test? Laboratory support for the diagnosis of Lyme borreliosis: a position paper of ESGBOR, the ESCMID study group for Lyme borreliosis.

BACKGROUND: Lyme borreliosis (LB) is a tick-borne infection caused by Borrelia burgdorferi sensu lato. The most frequent clinical manifestations are erythema migrans and Lyme neuroborreliosis. Currently, a large volume of diagnostic testing for LB is reported, whereas the incidence of clinically relevant disease manifestations is low. This indicates overuse of diagnostic testing for LB with implications for patient care and cost-effective health management. AIM: The recommendations provided in this review are intended to support both the clinical diagnosis and initiatives for a more rational use of laboratory testing in patients with clinically suspected LB. SOURCES: This is a narrative review combining various aspects of the clinical and laboratory diagnosis with an educational purpose. The literature search was based on existing systematic reviews, national and international guidelines and supplemented with specific citations. IMPLICATIONS: The main recommendations according to current European case definitions for LB are as follows. Typical erythema migrans should be diagnosed clinically and does not require laboratory testing. The diagnosis of Lyme neuroborreliosis requires laboratory investigation of the spinal fluid including intrathecal antibody production, and the remaining disease manifestations require testing for serum antibodies to B. burgdorferi. Testing individuals with non-specific subjective symptoms is not recommended, because of a low positive predictive value.

[The ecology of ticks, tick-borne diseases and biological tick control in Baden-Württemberg]. / Ökologie von Zecken als Überträger von Krankheitserregern in Baden-Württemberg und biologische Zeckenbekämpfung.

Ticks and tick-borne diseases are of great significance for the health of humans and animals. However, the factors influencing their distribution and dynamics are inadequately known. In a project financed by the Baden-Württemberg Ministry of the Environment, Climate and Energy Industry, as part of the program BWPLUS, interdisciplinary specialists work together to determine the influence of weather, (micro)climate, habitat, land use, human activities, and the population dynamics of host animals on the distribution and abundance of ticks and the diseases that they transmit in Baden-Württemberg. The project comprises four modules: the large-scale distribution of ticks in Baden-Württemberg (module 1), detailed studies of host-tick-pathogen interaction in relation to the microclimate (module 2), and the spatial occurrence of important tick-borne pathogens (module 3). The fourth module involves the comprehensive analysis and synthesis of all data in order to determine the relative importance of the factors studied and to develop a risk model. Recently, intensive investigations into tick control have been undertaken using various entomopathogenic fungi and nematodes as well as a parasitoid wasp. Our aim was to determine whether these natural enemies could be used to effectively reduce the number of free-living ticks.

Absorption engineering of NbN nanowires deposited on silicon nitride nanophotonic circuits.

We investigate the absorption properties of U-shaped niobium nitride (NbN) nanowires atop nanophotonic circuits. Nanowires as narrow as 20nm are realized in direct contact with Si3N4 waveguides and their absorption properties are extracted through balanced measurements. We perform a full characterization of the absorption coefficient in dependence of length, width and separation of the fabricated nanowires, as well as for waveguides with different cross-section and etch depth. Our results show excellent agreement with finite-element analysis simulations for all considered parameters. The experimental data thus allows for optimizing absorption properties of emerging single-photon detectors co-integrated with telecom wavelength optical circuits.

Effects of climate change on ticks and tick-borne diseases in europe.

Zoonotic tick-borne diseases are an increasing health burden in Europe and there is speculation that this is partly due to climate change affecting vector biology and disease transmission. Data on the vector tick Ixodes ricinus suggest that an extension of its northern and altitude range has been accompanied by an increased prevalence of tick-borne encephalitis. Climate change may also be partly responsible for the change in distribution of Dermacentor reticulatus. Increased winter activity of I. ricinus is probably due to warmer winters and a retrospective study suggests that hotter summers will change the dynamics and pattern of seasonal activity, resulting in the bulk of the tick population becoming active in the latter part of the year. Climate suitability models predict that eight important tick species are likely to establish more northern permanent populations in a climate-warming scenario. However, the complex ecology and epidemiology of such tick-borne diseases as Lyme borreliosis and tick-borne encephalitis make it difficult to implicate climate change as the main cause of their increasing prevalence. Climate change models are required that take account of the dynamic biological processes involved in vector abundance and pathogen transmission in order to predict future tick-borne disease scenarios.

Pathogens and host DNA in Ixodes ricinus nymphal ticks from a German forest.

Unfed nymphs of Ixodes ricinus were collected from vegetation in a forest on the outskirts of Berlin, Germany and were analyzed for host and pathogen DNA. Pathogens were detected in 47% of the ticks. Borrelia afzelii was the commonest pathogen detected, followed by Rickettsia helvetica. Other pathogens included B. valaisiana, B. garinii, B. burgdorferi sensu stricto, Anaplasma phagocytophilum, and a relapsing fever-like Borrelia. Most of the host DNA detected was of rodent origin and was associated with infection by B. afzelii, R. helvetica, and A. phagocytophilum. Bird DNA was associated with B. valaisiana and B. garinii, and ruminant DNA with A. phagocytophilum. B. afzelii was also found in two ticks that contained bird DNA.

Borrelia burgdorferi sensu lato in Ixodes ricinus ticks and rodents in a recreational park in south-western Ireland.

Ixodes ricinus ticks infected with Borrelia burgdorferi sensu lato were numerous on the edges of paths and roads in a recreational park in south-western Ireland. The abundance of ticks at different sites was related to the presence of deer, but a negative relationship was shown between tick abundance and tick infection rates. This is thought to be due to the deposition of large numbers of uninfected ticks by deer, which are apparently not good reservoir hosts of B. burgdorferi s.l. Blood meal analysis only detected deer DNA in uninfected nymphs. Reservoir competent rodents, Apodemus sylvaticus and Clethrionomys glareolus, were abundant at all sites and a high proportion of captured specimens were infested with larval ticks. However, very few rodents were infected with B. burgdorferi s.l. and none of the unfed infected nymphs analysed for the identity of their larval blood meal had fed on rodents. The spirochaetes detected in I. ricinus in the study area may be poorly adapted to rodents or are not transmitted readily because of the absence of nymphal infestation. The majority of spirochaetes in these ticks were apparently acquired from non-rodent hosts, such as birds.

Chemoprophylaxis for Lyme borreliosis?

Chemoprophylaxis is a term which describes treatment with an antimicrobial chemotherapeutic before, during or shortly after an actual or suspected exposure to an infectious agent in order to prevent clinical disease, which may be severe or even fatal. Lyme borreliosis is considered the most frequent ixodid-tick-transmitted human bacterial infection in the northern hemisphere. For several years there has been a debate on the prophylactic application of antimicrobial chemotherapeutics after an attached Ixodes tick was removed. Would this measure prevent a subsequent borrelia infection and would it be practical? People are exposed to tick-bites mostly during leisure spent in recreational areas which are often tick infested. The proportion of I. ricinus ticks infected with B. burgdorferi s. l. varies from area to area and in a given area also from year to year (infection rate up to a maximum of 55%). The transmission rate strongly depends on the duration of feeding, but it could be shown that the critical time of feeding is much shorter for European I. ricinus than for the North American I. scapularis or I. pacificus ticks. Nevertheless, even the low risk of complications despite the very good chance of treating erythema migrans successfully seems to justify prophylactic treatment for some investigators whilst others do not see an argument for this. Double blinded studies in the USA showed a relatively low frequency of illness after vector tick-bite and absence of disseminated disease manifestations. The efficacy of prophylactic antibiotic treatment after tick-bites is not established. Suggestions to examine removed ticks for borrelia in order to obtain indication for prophylactic antibiotic treatment will fail in practice because of high costs and uncertainty in verifying the transmission. Do we need blinded studies in central Europe on a representative number of cases, although it is known that Lyme borreliosis can be treated effectively even in its second and third stage and has never caused a fatal outcome? We conclude that only a reliable diagnosis of symptoms is the basis for a rational antibiotic treatment, and that instead of chemoprophylaxis for Lyme borreliosis after a vector tick-bite the wait and watch policy is recommended.

The pigeon tick (Argas reflexus): its biology, ecology, and epidemiological aspects.

The European pigeon tick, Argas reflexus (F.), is in central Europe predominantly an urban pest parasitizing wild and domesticated pigeons, Columba livia. Under certain circumstances, however, it also bites humans, occasionally causing an IgE-mediated type-I allergy. Control of A. reflexus is very difficult because of a number of remarkable morphological, physiological, and behavioural features of the tick. The present study aimed at elucidating the distribution and the frequency of occurrence of A. reflexus in Berlin and its possible vector role for Borrelia burgdorferi sensu lato (s. l.). Buildings reported by occupiers to be infested with A. reflexus were personally examined. In addition, the carrier status of this soft tick for B. burgdorferi (s. l.) was investigated in three German towns by an indirect immunofluorescence assay. A total of 188 Berlin buildings was found to be infested with A. reflexus between 1989 and 1998. Infestations were found in 17 out of the 21 districts, clustering in the inner city. There was only a single Borrelia-positive tick out of 800 sampled in Berlin, Leipzig, and Hannover using the genus specific antibody H9724. The same tick was PCR-negative for B. burgdorferi outer surface protein A. Neither these results nor those of other studies on the occurrence of antibodies against B. burgdorferi in pigeons suggest that field populations of A. reflexus and/or pigeons in central Europe harbour the causative agent of Lyme borreliosis.

Water balance of Dermatophagoides pteronyssinus (Acari: Pyroglyphidae) maintained by brief daily spells of elevated air humidity.

A facility was constructed to expose cultured Dermatophagoides pteronyssinus (Trouessart) to 24-h cycles of changing relative humidity; low humidity was interrupted every day by a period of high humidity. The temperature was kept at 16 degrees C, a common temperature on the ground floor of Dutch houses. Partially dehydrated mites were exposed to various humidity regimes in the absence of food and liquid water. Some mites gained weight when moist air was given for only 1.5 h every day. In the presence of food, egg production was recorded when moist air was given for at least 3 h daily, whereas the average relative humidity was quite low and less than the critical equilibrium humidity of D. pteronyssinus. Brief spells of elevated humidity allowed populations to survive much longer in a microclimate that was otherwise too dry, and may be decisive for survival during the winter months. We found that average relative humidity was misleading as an indicator of mite survival and growth conditions.

Ixodes ricinus strains in Europe.

An analysis of cuticular hydrocarbons (CH) of unfed adult Ixodes ricinus ticks collected throughout Europe showed that there are 10 distinct I. ricinus groups. Studies on the seasonal and annual consistency of CH composition and possible effects of host and environmental factors suggested that CHs may be used as a genuine genetic marker for I. ricinus. Preliminary studies compared the vector competence of ticks from three of the most separated I. ricinus groups and the results suggested that there may be significant differences in tick susceptibility to Borrelia afzelii.

European reservoir hosts of Borrelia burgdorferi sensu lato.

Existing knowledge on reservoir hosts of Borrelia burgdorferi sensu lato was collated and reviewed and several species, particularly birds, were identified as reservoir competent. At the present time, 9 small mammals, 7 medium-sized mammals and 16 bird species, including passerines, sea birds and pheasants, appear to be capable of transmitting spirochaetes to ticks and thus of participating in the natural circulation of B. burgdorferi s.l. in Europe. The house mouse, Mus musculus is strongly suspected of reservoir competence and many other small rodent species, particularly in eastern Europe and Russia, have been implicated. Ungulates are not thought to play a major role as reservoir hosts, though co-feeding transmission may permit some tick infection. The criteria for establishment of reservoir status are outlined and a method for identification of host blood meals of previous instars of unfed ticks, developed in a participant laboratory, is briefly described.

Lyme borreliosis habitat assessment.

Tick ecologists throughout Europe provided descriptions of Lyme borreliosis habitats according to a standardised format and data for 105 habitats in 16 countries were received. The data showed that high risk situations, as defined by the presence of large numbers of B. burgdorferi sensu lato-infected nymphal I. ricinus, occur in heterogeneous deciduous woodland, usually with a recreational function and with a diverse fauna, usually including deer. Large numbers of ticks occurred in some other habitats, but infection prevalence was usually low. The situation for adult I. ricinus was similar but less clearly defined. Tick infection rates were found to be lower in western Europe than in the east, and the infection rate in I. persulcatus, the most easterly vector species, was markedly higher than in I. ricinus. In the vast majority of habitats the infection rate in adult I. ricinus was greater than in nymphs. Larvae were rarely found to be infected.

Detection of Borrelia burgdorferi sensu lato in ticks: immunofluorescence assay versus polymerase chain reaction.

Immunofluorescence (IFA) and polymerase chain reaction (PCR) were examined as methods for detecting Borrelia burgdorferi sensu lato spirochaetes in unfed Ixodes ricinus nymphs. Although similar results were produced in some cases, a great deal of variation occurred. Furthermore, in both the highly controlled initial laboratory study, involving 252 shared samples, and the study on field-collected ticks (n = 460), the IFA tended to detect more infected ticks than the PCR. The basis for these findings are as yet undetermined. The development of a quality assurance scheme is recommended so that laboratories can validate their methods and a preliminary feasibility study suggested that such a scheme is practical.

Lyme borreliosis awareness.

A Lyme borreliosis information leaflet has been produced to promote awareness amongst the general public. It was designed to provide a framework for similar material throughout Europe and complements a questionnaire produced to measure awareness of Lyme borreliosis. This questionnaire can be used to determine the impact of educational campaigns using material such as the leaflet. Feasibility studies showed that the questionnaire successfully highlighted predictable differences between sample groups and also that the leaflet performed well in increasing knowledge in low-awareness groups.