Winter activity of questing ticks (Ixodes ricinus and Dermacentor reticulatus) in Germany - Evidence from quasi-natural tick plots, field studies and a tick submission study.

Changing climatic conditions and other anthropogenic influences have altered tick distribution, abundance and seasonal activity over the last decades. In Germany, the two most important tick species are Ixodes ricinus and Dermacentor reticulatus, the latter of which has expanded its range across the country during the past three decades. While I. ricinus was rarely found during the colder months in the past, D. reticulatus is known to be active at lower temperatures. To quantify tick appearance during winter, specimens were monitored in quasi-natural tick plots three times a week. Additionally, the questing activities of these two tick species were observed throughout the year at nine field collection sites that were regularly sampled by the flagging method from April 2020 to April 2022. Furthermore, tick winter activity in terms of host infestation was analysed as part of a nationwide submission study from March 2020 to October 2021, in which veterinarians sent in ticks mainly collected from dogs and cats. All three study approaches showed a year-round activity of I. ricinus and D. reticulatus in Germany. During the winter months (December to February), on average 1.1% of the inserted I. ricinus specimens were observed at the tops of rods in the tick plots. The average questing activity of I. ricinus amounted to 2 ticks/100 m² (range: 1-17) in the flagging study, and 32.4% (211/651) of ticks found infesting dogs and cats during winter 2020/21 were I. ricinus. On average 14.7-20.0% of the inserted D. reticulatus specimens were observed at the tops of rods in the tick plots, while the average winter questing activity in the field study amounted to 23 specimens/100 m² (range: 0-62), and 49.8% (324/651) of all ticks collected from dogs and cats during winter 2020/21 were D. reticulatus. Additionally, the hedgehog tick Ixodes hexagonus was found to infest dogs and cats quite frequently during the winter months, accounting for 13.2% (86/651) of the collected ticks. A generalized linear mixed model identified significant correlations of D. reticulatus winter activity in quasi-natural plots with climatic variables. The combined study approaches confirmed a complementary main activity pattern of I. ricinus and D. reticulatus with climate change-driven winter activity of both species. Milder winters and a decrease of snowfall, and consequently high winter activity of D. reticulatus, among other factors, may have contributed to the rapid spread of this tick species throughout the country. Therefore, an effective year-round tick control is strongly recommended to not only efficiently protect dogs and cats with outdoor access from ticks and tick-borne pathogens (TBPs), but also to limit the further geographical spread of ticks and TBPs to so far non-endemic regions. Further measures, including information of the public, are necessary to protect both, humans and animals, in a One Health approach.

Ticks in the metropolitan area of Berlin, Germany.

A high-resolution city map showing the geographic distribution of 12 tick species (Acari: Argasidae, Ixodidae) that have been recorded from the metropolitan area of Berlin, Germany is presented. A total of 237 tick locations was mapped. These include ten ixodid tick species: Dermacentor reticulatus, Haemaphysalis concinna, Hyalomma rufipes, Ixodes ricinus, Ixodes canisuga, Ixodes hexagonus, Ixodes arboricola, Ixodes frontalis, Ixodes trianguliceps and Rhipicephalus sanguineus sensu lato. The two tick species Hy. rufipes and R. sanguineus s.l. are not endemic to Berlin. Hyalomma rufipes ticks are introduced in Europe with migratory birds from Africa every spring. Rhipicephalus sanguineus s.l. are introduced to Central Europe with dogs that had travelled to or were imported from countries where this tick is endemic. In Germany, they are able to develop and reproduce inside heated buildings. Occurrences of two soft tick species, the pigeon tick Argas reflexus and the short-legged bat tick Carios vespertilionis were also mapped. Other tick species that are likely to be endemic to Berlin and its environs, but for which documented findings or geographical coordinates are lacking, are mentioned. These include the long-legged bat tick I. vespertilionis and the marten tick I. rugicollis documented in Brandenburg, the federal state surrounding Berlin. It can be assumed that if appropriate field studies are carried out, these tick species will also be found in the metropolitan area of Berlin. The high-resolution mapping of all tick species found in a city (like Berlin) forms the basis for further investigations into the impact of climate change and changing land use on ticks and tick-borne diseases, precisely in those habitats where most people will live in the future.

Atlas of ticks (Acari: Argasidae, Ixodidae) in Germany.

An updated and increased compilation of georeferenced tick locations in Germany is presented here. This data collection extends the dataset published some years ago by another 1448 new tick locations, 900 locations of which were digitized from literature and 548 locations are published here for the first time. This means that a total of 3492 georeferenced tick locations is now available for Germany. The tick fauna of Germany includes two species of Argasidae in the genera Argas and Carios and 19 species of Ixodidae in the genera Dermacentor, Haemaphysalis, and Ixodes, altogether 21 tick species. In addition, three species of Ixodidae in the genera Hyalomma (each spring imported by migratory birds) and Rhipicephalus (occasionally imported by dogs returning from abroad with their owners) are included in the tick atlas. Of these, the georeferenced locations of 23 tick species are depicted in maps. The occurrence of the one remaining tick species, the recently described Ixodes inopinatus, is given at the level of the federal states. The most common and widespread tick species is Ixodes ricinus, with records in all 16 federal states. With the exception of Hamburg, Dermacentor reticulatus was also found in all federal states. The occurrence of the ixodid ticks Ixodes canisuga, Ixodes frontalis, Ixodes hexagonus and I. inopinatus were documented in at least 11 federal states each. The two mentioned argasid tick species were also documented in numerous federal states, the pigeon tick Argas reflexus in 11 and the bat tick Carios vespertilionis in seven federal states. The atlas of ticks in Germany and the underlying digital dataset in the supplement can be used to improve global tick maps or to study the effects of climate change and habitat alteration on the distribution of tick species.

High efficacy of a dimeticone-based pediculicide following a brief application: in vitro assays and randomized controlled investigator-blinded clinical trial.

BACKGROUND: Increasing resistance of head lice against neurotoxic agents and safety concerns have led to the search for treatment alternatives. Dimeticones with a physical mode of action are safe, and bear a reduced risk for the development of resistance. METHODS: We performed in vitro bioassays to assess pediculicidal and ovicidal activities of a new dimeticone-based product, and a randomized controlled clinical trial to assess efficacy, following 10 min application. Of 153 individuals screened, 100 participants with active head louse infestations were randomly assigned to treatment with either a dimeticone-based test product, or a 0.5% permethrin-based reference product (50 participants per group). Participants received two topical applications of either the test (10 min) or reference products (45 min) at days 0 and 7 or 8. Outcome measures included the efficacies of treatment and their safety, as well as global and local tolerability at baseline, and days 1, 7, and 10. RESULTS: After 10 min exposure, all lice treated with the dimeticone test product were classified as non-viable in the in vitro assay. Ovicidal activity after treatment of eggs with the dimeticone test product was 96.8%. In the clinical trial, 96 patients completed all study visits. In the full analysis set (FAS) population, on day 1 after one application, 98% of patients were cured in the test group, as compared to 84% cured in the reference group. All participants in both groups were free of head lice on day 10, following two applications (100% cure rate). In total, 42 adverse events (AEs) in 23 patients of both treatment groups were recorded, with the majority of AEs classified as mild. CONCLUSIONS: We have shown a high level of pediculicidal and ovicidal activity, and clinical efficacy and safety, of a brief application of a new dimeticone-based product. The short application time and reduced risk for the development of resistance are key drivers for improved patients' compliance. TRIAL REGISTRATION: EU Clinical Trials Register EudraCT  2016-004635-20 . Registered 14 November 2016.

A Density Map of the Tick-Borne Encephalitis and Lyme Borreliosis Vector Ixodes ricinus (Acari: Ixodidae) for Germany.

The castor bean tick Ixodes ricinus (L.) is the principal vector for a variety of viral, bacterial, and protozoan pathogens causing a growing public-health issue over the past decades. However, a national density map of I. ricinus is still missing. Here, I. ricinus nymphs in Germany were investigated by compiling a high-resolution map depicting the mean annually accumulated nymphal density, as observed by monthly flagging an area of 100 m2 Input data comprise ticks collected at 69 sampling sites. The model domain covers an area of about 357,000 km2 (regional scale). Two negative binomial regression models were fitted to the data to interpolate the tick densities to unsampled locations using bioclimatic variables and land cover, which were selected according to their significance by the Akaike information criterion (AIC). The default model was fitted to the complete dataset resulting in AIC = 842. An optimized model resulted in a significantly better value of AIC = 732. Tick densities are very low in urban (green) areas. Maximum annual densities up to 1,000 nymphs per 100 m2 are observed in broad-leaved forests. The tick maps were verified by leave-one-out cross-validation. Root mean square errors of RMSE = 137 and RMSE = 126 nymphs per 100 m2 were estimated for the two models, respectively. These errors are of the order of the interannual variation of the tick densities. The compilation of a high-resolution density map of unfed nymphal I. ricinus for Germany provides a novel, nationwide insight into the distribution of an important disease vector.

Geographical distribution of Dermacentor marginatus and Dermacentor reticulatus in Europe.

The goal of this paper is to present up-to-date maps depicting the geographical distribution of Dermacentor species in Europe based on georeferenced sampling sites. Therefore, a dataset was compiled, resulting in 1286 D. marginatus (Sulzer, 1776) and 1209 D. reticulatus (Fabricius, 1794) locations. Special emphasis is given to the region of the European Alps depicting a presumable climate barrier of the mountains and to overlaps in the distribution of both species as well as on the situation in eastern European countries. For the latter newly described Dermacentor findings comprise 59 locations in Romania and 62 locations in Ukraine. The geographical distributions of both species in Europe range from Portugal to Ukraine (and continue to the east of Kazakhstan). Although it is well known that D. marginatus is adapted to a warmer and drier climate at more southern latitudes and D. reticulatus to a moderately moist climate at more northern latitudes, the distribution limits of both species were not well known. Here, the northern and southern distribution limits for both species in Europe, as determined from the georeferenced database, were specified for D. marginatus by the belt of 33-51° N latitude and for D. reticulatus by the belt of 41-57° N latitude. Thus, overlapping species distributions were found between 41° N and 51° N.

Repellent efficacy of DEET, Icaridin, and EBAAP against Ixodes ricinus and Ixodes scapularis nymphs (Acari, Ixodidae).

Repellent efficacy of 10% EBAAP (3-[N-butyl-N-acetyl]-aminopropionic acid, ethyl ester) and 10% Icaridin ((2-(2-hydroxyethyl)-1-piperidinecarboxylic acid 1-methylpropyl ester)) were evaluated against 20% DEET (N,N-diethyl-3-methylbenzamide) in human subject trials against ticks. Responses of host-seeking nymphs of the European castor bean tick (Ixodes ricinus L.; Acari: Ixodidae) and the North American blacklegged tick (I. scapularis Say; Acari: Ixodidae) were compared. Tests were carried out according to the US-EPA standard protocol with ethanolic solutions of the active ingredients of repellents being applied to the forearm of 10 volunteers. The upward movement of ticks was monitored until repellent failure taking up to 12.5 h. Application of 20% DEET resulted in median complete protection times (CPT; Kaplan-Meier median) between 4 and 4.5 h, while 10% EBAAP yielded CPTs of 3.5-4h. No significant differences were found between the efficacies of two repellents nor between the two species tested. The median of the CPT of a 10% Icaridin solution was 5h in nymphs of I. scapularis, but 8h in those of I. ricinus (P<0.01). Based on these studies, EBAAP and Icaridin are efficacious alternatives to DEET in their repellent activity against nymphs of the two Ixodes ticks with Icaridin demonstrating particularly promising results against I. ricinus. Future research should investigate whether similar results occur when adult Ixodes ticks or other tick species are tested.

Long-term in vitro cultivation of Borrelia miyamotoi.

Borrelia are fastidious bacteria some of which are difficult to grow in vitro. Here, we report a method for successful continuous in vitro cultivation of the emerging pathogen Borrelia miyamotoi. The type and quantity of serum as well as the atmosphere were critical for successful in vitro cultivation. Optimal growth was achieved using 50% pooled human serum and an atmosphere of 6% CO2.

The first German map of georeferenced ixodid tick locations.

BACKGROUND: Georeferenced locations of ixodid ticks are required to depict the observed distribution of species. Further, they are used as input data for species distribution models also known as niche models. The latter were applied to describe current and future (projected) tick distributions. Beside model assumptions and selected climate parameters, the number of georeferenced tick locations available as a digital dataset is of fundamental importance for the reliability of such models. For Germany, however, no comprehensive dataset of ixodid tick species exists. The goal of this study was to put together all the available information on ixodid tick locations in Germany to produce such a digital dataset and to visualize it in a map. FINDINGS: A total of 2,044 georeferenced locations of ixodid ticks in Germany were compiled from two existing datasets (altogether 993 locations) and an extensive literature study (1,051 locations). The resulting digital dataset comprises the following tick species: Ixodes ricinus (1,855 locations), Ixodes apronophorus (1), Ixodes frontalis (1), Ixodes hexagonus (1), Ixodes trianguliceps (4), Dermacentor marginatus (77), Dermacentor reticulatus (96), Haemaphysalis concinna (8) and Hyalomma marginatum (1). The data were used to draw a tick map for Germany, showing I. ricinus occurring in the whole federal territory, while D. marginatus has been restricted to the climatically favoured region of the Rhine valley. Clustered locations of D. reticulatus were also documented in the Rhine valley as well as in Berlin and its vicinity. CONCLUSIONS: The introduced map depicts for the first time the available geographical coordinates of ixodid tick locations in Germany. The digital dataset used to draw the map is provided to the scientific community as a basis for further investigations such as species distribution modelling.

Tick repellents for human use: prevention of tick bites and tick-borne diseases.

Ticks are arthropods and the most important vectors of major human diseases after mosquitoes. Due to their impact on public health, in vitro and in vivo assays have been developed to identify molecules with repellent activities on ticks. Repellents are useful to reduce tick bite exposure and the potential transmission of pathogens; they can be used topically or in impregnated clothing. Presently, mainly synthetic molecules are commercialized as skin repellents, e.g., N,N-diethyl-meta-toluamide (DEET), IR3535, picaridin or KBR 3023, and para-menthanediol. Permethrin is largely used for fabric impregnation. Intensive research has been conducted to identify new molecules with repellent activity and more recently, plant-derived molecules, as an alternative to synthetic molecules.

Efficacy testing of several Ixodes ricinus tick repellents: different results with different assays.

In the European Union (EU), tick repellents for humans need to be registered and approved by the authorities in order to be marketed. As there are currently no specific technical guidelines for product evaluation, we compared 3 different test methods: the mechanical moving object bioassay (MOB), and 2 assays involving human volunteers. For the latter, procedures according to the U.S. Environmental Protection Agency (EPA) and the Stiftung Warentest (StiWa), a German consumer care organization, were used. Two repellents, Autan(®) (AU), based on 20% Picaridin [2-(2-hydroxyethyl)-1-piperidinecarboxylic acid-1-methylpropyl ester], and ZeckWeck (ZW), based on 12.5g/100g Citriodiol™ (main compound: p-menthane-3,8-diol) were tested with all 3 assays. Three repellents, Anti Brumm(®) naturelle, based on 20% Citriodiol™ (main compound: p-menthane-3,8-diol), G090141, based on 20% EBAAP (ethyl buthyl acetyl aminopropionate), and G090152, based on 10% decanoic acid (capric acid), which is contained in Zanzarin(®), were tested according to the EPA and the StiWa procedures. The EPA assay indicated a significantly higher repellency of the products AU and G090141 than the StiWa test, but no difference between assays could be detected for the remaining 3 products. Also the corresponding protection times were significantly longer (approximately 4h) when determined according to EPA versus to StiWa for 3 of the products, whilst the difference was insignificant for ZW and G090152. Additionally, significantly lower numbers of ticks initially walked onto the repellent-treated skin when tested according to EPA versus to StiWa in all products except ZW and G090152. Thus, the StiWa protocol appears to pose higher demands on a repellent than the EPA method. Contrary to expectation, the MOB showed the same or even lower product efficacy when compared to the EPA and StiWa tests. Particularly, the percentage of ticks clinging to repellent-treated filter paper was significantly higher than the proportion of ticks walking onto treated skin in the other assays. This could mean that in nature more ticks may probably cling to a human protected by a given repellent than the EPA or the StiWa assay might suggest. Nevertheless, the MOB produced results that are quite similar to the tests involving human volunteers.

Species determination and characterization of developmental stages of ticks by whole-animal matrix-assisted laser desorption/ionization mass spectrometry.

Matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) of crude bacterial samples has been introduced as a very cost-efficient and rapid, yet highly informative tool to identify and classify bacteria. The potential of this approach to characterize whole animals, so far preferentially insects, is only evolving. Here, a simple protocol was developed to perform MALDI-MS analysis on extracts from whole ticks of 7 species and 4 developmental stages. Using commercially available software designed for the identification of bacteria, a reference database of spectra was constructed that allowed the species determination of ticks using larvae, nymphs, or adult individuals as starting material. Cluster analysis on the basis of MALDI mass spectra indicated that the primary determinant for the mass spectra was the species, followed by the developmental stages, which formed distinct clusters within the given species. With certain limitations, species identification was also possible using body parts and engorged animals. Spectra of developing Ixodes ricinus eggs showed dramatic changes with time, suggesting that, beyond its usefulness for species determination, MALDI-typing may have applications in developmental biology.

Natural isotope signatures of host blood are replicated in moulted ticks.

This proof-of-concept study demonstrates that stable isotope ratios of nitrogen and carbon (expressed as δ(13)C and δ(15)N) of host blood are faithfully reproduced in unfed nymphal Ixodes ricinus that developed from larvae fed on that host. Measured isotopic discrimination (i.e. the tick-blood spacing) was between -0.1 and 0.7‰ for δ(13)C and 3.8 and 3.9‰ for δ(15)N. Both δ(13)C and δ(15)N increased significantly with tick ageing. The isotopic analysis of unfed ticks has potential for determining the physiological age of unfed ticks, for identifying the season in which the previous stage had fed and for identifying the main hosts utilized by ticks.

Differentiation of medically important Euro-Asian tick species Ixodes ricinus, Ixodes persulcatus, Ixodes hexagonus, and Dermacentor reticulatus by polymerase chain reaction.

Understanding epidemiology of the tick-borne pathogens requires the accurate identification of the vector ticks. Morphological analysis of ticks is difficult and often leads to misidentification. Molecular techniques offer an alternative approach of tick identification. To date, no practical and reliable molecular assays for discrimination of Euro-Asian ticks are available. Our aim was to develop such an assay for discrimination between four Euro-Asian tick species of high medical importance such as Ixodes ricinus, Ixodes persulcatus, Ixodes hexagonus, and Dermacentor reticulatus. As a basis, we have chosen conventional species-specific polymerase chain reaction (PCR), a technique providing a good combination of simplicity and reliability. The DNA information available on ticks was searched for orthologous loci containing stretches of sequence dissimilarity sufficient for designing species-specific primers. ITS2 locus (second internal transcribed region of the rRNA gene cluster) was found to be the most favorable for primer design. Finally, for each of the three Ixodes species a PCR was developed amplifying only for the targeted species. One PCR amplified the entire ITS2 locus of the four species and allowed discrimination of D. reticulatus from the Ixodes species on the basis of the size difference of the respective PCR products. This PCR system was successfully tested for discrimination of the ticks at different maturation stages (larva, nymph, and adult) in engorged and unfed conditions, and therefore it may be useful for large-scale epidemiological studies. Differentiation between the closely related I. ricinus and I. persulcatus, the two species most often occurring in the tick-borne diseases in Eurasia, is of special importance.

Tick-borne encephalitis in the age of general mobility.

The 11th meeting of the International Scientific Working Group on Tick-borne Encephalitis (ISW-TBE) was conducted under the title of, "From childhood to golden age: increased mobility - increased risk of contracting TBE?" Participants from 26 countries, including the United States of America and China, presented reports on the latest developments and trends in local TBE cases, vaccination coverage and risk factors. In particular, the situation of children and the elderly (the "golden agers") was discussed. As the current evidence suggests, the location and extension of endemic areas for TBE have changed over the last few years, along with global warming and the shift of infected ticks to higher altitudes. The increased mobility of the human population adds to the heightened exposure; outdoor activities and international travel are on the rise also, and especially, amongst the 50+ generation, who are already per se at higher risk of disease manifestation, complications and case fatality. Most Europeans travel within Europe, often without sufficient awareness of endemic areas. Only high immunization rates can ensure low disease rates in the long run. To achieve this goal, public education is the sole effective approach for raising the level of awareness. Overall, the risk of any given person to contract TBE should not be regarded as a fixed entity, but rather it must be estimated individually, on the basis of knowledge of the TBE virus endemic areas and risk factors.

Prevention of infectious tick-borne diseases in humans: Comparative studies of the repellency of different dodecanoic acid-formulations against Ixodes ricinus ticks (Acari: Ixodidae).

BACKGROUND: Ticks of the species Ixodes ricinus are the main vectors of Lyme Borreliosis and Tick-borne Encephalitis - two rapidly emerging diseases in Europe. Repellents provide a practical means of protection against tick bites and can therefore minimize the transmission of tick-borne diseases. We developed and tested seven different dodecanoic acid (DDA)-formulations for their efficacy in repelling host-seeking nymphs of I. ricinus by laboratory screening. The ultimately selected formulation was then used for comparative investigations of commercially available tick repellents in humans. METHODS: Laboratory screening tests were performed using the Moving-object (MO) bioassay. All test formulations contained 10% of the naturally occurring active substance DDA and differed only in terms of the quantitative and qualitative composition of inactive ingredients and fragrances. The test procedure used in the human bioassays is a modification of an assay described by the U.S. Environmental Protection Agency and recommended for regulatory affairs. Repellency was computed using the equation: R = 100 - NR/N x 100, where NR is the number of non-repelled ticks, and N is the respective number of control ticks. All investigations were conducted in a controlled laboratory environment offering standardized test conditions. RESULTS: All test formulations strongly repelled nymphs of I. ricinus (100-81% protection) as shown by the MO-bioassay. The majority of ticks dropped off the treated surface of the heated rotating drum that served as the attractant (1 mg/cm2 repellent applied). The 10% DDA-based formulation, that produced the best results in laboratory screening, was as effective as the coconut oil-based reference product. The mean protection time of both preparations was generally similar and averaged 8 hours.Repellency investigations in humans showed that the most effective 10% DDA-based formulation (~1.67 mg/cm2 applied) strongly avoided the attachment of I. ricinus nymphs and adults for at least 6 hours. The test repellent always provided protection (83-63%) against I. ricinus nymphs equivalent to the natural coconut oil based reference product and a better protection (88-75%) against adult ticks than the synthetic Icaridin-containing reference repellent. CONCLUSION: We found that the 10% DDA-based formulation (ContraZeck(R)) is an easily applied and very effective natural repellent against I. ricinus ticks. By reducing the human-vector contact the product minimises the risk of transmission of tick-borne diseases in humans.

Evidence for an increased geographical distribution of Dermacentor reticulatus in Germany and detection of Rickettsia sp. RpA4.

Two studies were performed to elucidate the current distribution of the tick Dermacentor reticulatus in Germany. In the first one in 2003, a total of 365 dogs from 171 sites in the states of Berlin and Brandenburg was screened for ticks, and the corresponding outdoor sites that the dogs usually visited were searched for host-seeking ticks by the flagging method. A total of 1155 ticks was removed from the dogs. The majority were Ixodes ricinus (88.5%), followed by D. reticulatus (9.1%) and I. hexagonus (2.4%). Altogether, 222 dogs carried I. ricinus (60.8%), 41 D. reticulatus (11.2%) and 15 I. hexagonus (4.1%) ticks. Based on scutal index determination, the removed I. ricinus and D. reticulatus had been feeding on the dogs for a mean of 4.0 and 4.5 days, respectively. The dogs infested with D. reticulatus lived at 26 different sites, all previously unknown as Dermacentor sites. Seven of the sites could be confirmed subsequently by flagging the vegetation for ticks. In the second study, a total of 721 deer was shot at 201 different sites from a total of 160 districts all over Germany during the autumn hunting season 2004. A total of 23 deer (3.2%) originating from 14 sites was infested with D. reticulatus. Hereby, significantly more red deer (Cervus elaphus elaphus) than roe deer (Capreolus capreolus) or fallow deer (Dama dama) harboured D. reticulatus ticks. Only two of the sites found had already been known as D. reticulatus areas, whereas all other sites in Brandenburg, Saxony Anhalt, Hesse and Bavaria had been unknown. The results of both studies show that D. reticulatus presently occurs at far more sites than previously known in Germany and thus most likely has expanded its range. Additionally, a total of 135 D. reticulatus removed from deer was screened for Babesia canis and Rickettsia sp. by PCR. A total of 31 D. reticulatus (23%) were positive for Rickettsia. Sequencing revealed in all cases 100% identity with the strain RpA4 that was first isolated from Rhipicephalus ticks in Russia.

Bites of the European pigeon tick (Argas reflexus): Risk of IgE-mediated sensitizations and anaphylactic reactions.

BACKGROUND: Local and systemic reactions can occur after bites of Argas reflexus (Argas), a soft tick parasitizing pigeons. OBJECTIVE: Risk assessment of IgE-mediated sensitizations and systemic reactions after Argas bites. METHODS: Case histories, skin prick tests (SPTs) with a whole-body extract of Argas containing major allergen Arg r 1, and common inhalants and specific IgE measurements were obtained from 148 subjects who had had Argas bites and 20 volunteers as a control group. RESULTS: Systemic reactions (urticaria, angioedema, dyspnea, cardiovascular dysregulation, unconsciousness) were reported in 12 of 148 (8%); 146 of 148 (99%) had local reactions. Atopy was found in 37 of 146 (25%) with local reactions and 3 of 12 (25%) with systemic reactions. SPT to Argas was positive in 24 of 148 (16%) with a high proportion of atopics 10 of 24 (42%); specific IgE to Argas was detectable in 12 of 135 (8% of 148) with moderate concordance to systemic reactions. No positive SPT or specific IgE results to Argas were obtained in the control group. Immunoblotting of 23 sera revealed an IgE-binding protein in 19 of 23 sera (82%) at 22 kd, indicating a major allergen of Argas. CONCLUSION: Severe anaphylactic reactions were infrequently (approximately 8%) found after bites of the soft tick Argas reflexus. Atopy is a risk factor for skin sensitizations to Argas, but not for systemic reactions after bites by Argas. Using a whole-body extract of Argas, diagnosis through SPT and specific IgE is hampered by false-negative and irrelevant positive results, particularly in atopy.

Test systems for tick repellents.

There is an interest in the development of repellents for personal protection of humans and animals against ticks. Evaluation of new substances or formulations needs adequate test procedures to show efficacy of the compounds. A variety of repellent assays for ticks are described in the literature. Available biotests can be grouped in three categories (i) use of live hosts, (ii) use of some kind of tick attractant associated with hosts, or (iii) no use of attractants at all. The latter are often better to standardize and are cheap, but suffer from a poor ability to filter out weak repellents. The former two are usually more predictive in terms of forecasting the efficacy of the product under practical conditions, although sometimes difficult to standardize, particularly in the field, but usually expensive and time consuming. Therefore, recent developments concentrated on laboratory assays like the Moving-object bioassay or the human volunteer test, allowing the tick to display its host-seeking behaviour as close as possible to that shown in nature, yet offering a standardized procedure.