Austrian hard ticks as vectors of Borrelia burgdorferi, overview

Bacteria and protozoa with pathogenic potential in Ixodes ricinus ticks in Viennese recreational areas

Ixodes ricinus is the most relevant vector for tick-borne diseases in Austria and responsible for the transmission of Borrelia burgdorferi sensu lato (s. l.), which causes Lyme borreliosis in humans; however, also other bacteria and protozoa can be found in ticks and have the potential of infecting people and animals. In this study we collected ticks in popular recreational areas in the city of Vienna in the years 2019 and 2020 and analyzed them for the presence of such putative pathogenic microorganisms. By using reverse line blot (RLB) hybridization we detected DNA of B. burgdorferi s. l., Rickettsia spp., Babesia spp., Candidatus Neoehrlichia mikurensis (CNM) and Anaplasma phagocytophilum. Moreover, we also screened them for the relapsing fever spirochete Borrelia miyamotoi employing real-time PCR. The most frequently detected pathogens were B. burgdorferi s. l. in 28.6% of the ticks in 2019 and 21.3% of the ticks in 2020. The genus Rickettsia was detected in 13.8% of the ticks from 2019 and only in 4.6% from 2020. Babesia spp. were detected in 5.7% in 2019 and 4.2% in 2020. Furthermore, we detected CNM in 4.0% (2019) and 5.6% (2020), A. phagocytophilum in 0.5% (2019) and 1.3% (2020) and finally B. miyamotoi in 3.3% (2019) and 1.7% (2020). Collectively, we show that various microorganisms are prevalent in ticks collected in Vienna and identify hotspots for B. miyamotoi, which we have detected for the first time in the city.

Vector Surveillance and Pathogen Detection in the Working Areas of Military Working Dogs in Eastern Austria

Vector-borne diseases play a major role in human and veterinary medicine worldwide. A previous study detected asymptomatic vector-borne pathogens in military working dogs stationed at a military base in eastern Austria, and a follow-up survey of potential arthropod vectors was conducted in spring 2019 and 2020 in the vicinity of the base to evaluate the presence of vectors and their carrier status for a range of canine and zoonotic pathogens. A total of 1324 ticks (nymphs and adults of Ixodes ricinus, comprising 92.9% of the collected specimens, and adults of Haemaphysalis inermis, a tick previously only rarely described in Austria, Haemaphysalis concinna, and Dermacentor reticulatus) were collected by flagging. In 44.1% (125/284) of all pools (n = 284), one infectious agent was found; in 27.8% (79/284) and in 1.1% (3/284), two and three different agents, respectively, could be identified. Overall, 72.9% of the pools contained at least one pathogen (Borrelia spp., Rickettsia spp., Bartonella spp., and Babesia microti). Borrelia mijamotoi, B. lustinaniae, and B. microti were previously only described in single cases in Austria. Mosquitoes were collected with BG-Sentinel traps monthly during the summer of 2019. A total of 71 individuals from 11 species were collected. No filarioid DNA was detected in the mosquito sample pools, although Dirofilaria repens had been present in the dogs from the military site. In conclusion, vector surveillance should be combined with the surveillance of an exposed population whenever possible to estimate the infection risks for dogs and their handlers.

Maps of ticks (Acari: Argasidae, Ixodidae) for Austria and South Tyrol, Italy

A first compilation of georeferenced tick locations in Austria and South Tyrol, Italy, is presented here. This allows the tick fauna to be examined in the various climatic regions of the European Alps. The dataset comprises 424 tick locations of Austria and 48 tick locations of South Tyrol, which were digitized from literature and visualized in the form of geographical maps. The tick fauna of Austria includes two species of Argasidae in the genera Argas and Carios and 15 species of Ixodidae in the genera Dermacentor, Haemaphysalis, and Ixodes, altogether 17 tick species. In addition, two 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 18 tick species are depicted in maps. The occurrence of the one remaining tick species, Ixodes inopinatus, is given at the level of the federal states. The first Austrian distribution map of the long-legged bat tick Ixodes vespertilionis, which was reported from 21 caves, deserves special mention. The most common and widespread tick species is Ixodes ricinus, with records in all nine federal states of Austria, followed by Ixodes canisuga, Ixodes hexagonus, and I. vespertilionis in six federal states each. Haemaphysalis concinna and Dermacentor reticulatus are only endemic in the eastern plains, while Dermacentor marginatus only occurs in the west, in the Tyrolean Alpine valleys. Eight tick species were reported from South Tyrol, Italy. There, the most frequently flagged tick from the vegetation is also I. ricinus, while D. marginatus and Haemaphysalis punctata are often collected from sheep. The locations are shown together with those from North and East Tyrol on a separate Tyrol map. The tick atlas in Austria and South Tyrol as well as the underlying digital dataset in the supplement contribute to the closing of data gaps in global distribution maps of ticks and improve the data basis for new species distribution models.

Approaches for Reverse Line Blot-Based Detection of Microbial Pathogens in Ixodes ricinus Ticks Collected in Austria and Impact of the Chosen Method

Ticks transmit a large number of pathogens capable of causing human disease. In this study, the PCR-reverse line blot (RLB) method was used to screen for pathogens in a total of 554 Ixodes ricinus ticks collected from all provinces of Austria. These pathogens belong to the genera Borrelia, Rickettsiae, Anaplasma/Ehrlichia (including "Candidatus Neoehrlichia"), Babesia, and Coxiella The pathogens with the highest detected prevalence were spirochetes of the Borrelia burgdorferisensu lato complex, in 142 ticks (25.6%). Borrelia afzelii (80/142) was the most frequently detected species, followed by Borrelia burgdorferisensu stricto (38/142) and Borrelia valaisiana (36/142). Borrelia garinii/Borrelia bavariensis, Borrelia lusitaniae, and Borrelia spielmanii were found in 28 ticks, 5 ticks, and 1 tick, respectively. Rickettsia spp. were detected in 93 ticks (16.8%): R. helvetica (39/93), R. raoultii (38/93), R. monacensis (2/93), and R. slovaca (1/93). Thirteen Rickettsia samples remain uncharacterized. "Candidatus Neoehrlichia mikurensis," Babesia spp. (B. venatorum, B. divergens, B. microti), and Anaplasma phagocytophilum were found in 4.5%, 2.7%, and 0.7%, respectively. Coxiella burnetii was not detected. Multiple microorganisms were detected in 40 ticks (7.2%), and the cooccurrence of Babesia spp. and "Candidatus Neoehrlichia mikurensis" showed a significant positive correlation. We also compared different PCR-RLBs for detection of Borrelia burgdorferisensu lato and Rickettsia spp. and showed that different detection approaches provide highly diverse results, indicating that analysis of environmental samples remains challenging.IMPORTANCE This study determined the wide spectrum of tick-borne bacterial and protozoal pathogens that can be encountered in Austria. Surveillance of (putative) pathogenic microorganisms occurring in the environment is of medical importance, especially when those agents can be transmitted by ticks and cause disease. The observation of significant coinfections of certain microorganisms in field-collected ticks is an initial step to an improved understanding of microbial interactions in ticks. In addition, we show that variations in molecular detection methods, such as in primer pairs and target genes, can considerably influence the final results. For instance, detection of certain genospecies of borreliae may be better or worse by one method or the other, a fact of great importance for future screening studies.

Seasonal and spatial distribution of ixodid tick species feeding on naturally infested dogs from Eastern Austria and the influence of acaricides/repellents on these parameters

Background

Effective control of tick infestation and pathogen transmission requires profound knowledge of tick biology in view of their vector function. The particular time of the year when the different tick species start to quest and the favoured sites on the canine host are of major interest. The efficacy of acaricides/repellents to control ticks in the field requires observation.

Methods

To address these issues, 90 dogs, grouped in “untreated”, “acaricide/repellent” (permethrin) and “acaricide only” (fipronil) animals and subjected to tick infestation under natural conditions in Burgenland (Eastern Austria), were examined. The number and species of ticks occurring during and outside the protection time was evaluated during a period of 11 months and the biting location on the dogs’ skin was recorded.

Results

Of the 700 ticks collected, the most common species in that particular walking area was Ixodes ricinus, followed by Dermacentor reticulatus and Haemaphysalis concinna. Regarding the on-host activity, D. reticulatus displayed more infestations in early spring and late autumn, whereas I. ricinus occurred almost one month later in spring and one month earlier in autumn. H. concinna followed a monophasic pattern of activity with a peak in summer. The preferred feeding sites of the ticks on the dogs were on the head, neck, shoulder and chest. This distribution over the dog’s body was not influenced by the use of the drugs, although on the whole fewer ticks (22.5% of all ticks) were found during the protection time. Interestingly, differences occurred with the use of drugs compared to non-protected dogs with regard to the infestation over the year. Acaricide-treated dogs displayed a higher prevalence in April, May and September, whereas dogs of the acaricide/repellent group showed a higher infestation in March, July, October and November.

Conclusion

The different tick species display different on-dog activity peaks over the year, during which particular canine diseases can be expected and predicted, considering the specific incubation times for each pathogen.

The tick species occurring in this study do not seem to choose particular sites on the dogs. Their arrival place seems to represent the attachment and consequently the feeding sites. The use of acaricides leads to a significantly (p<0.01) lower number of infesting ticks but no change of the distribution pattern on the dogs was observed.

[Pandora's Box: pathogens in Ixodes ricinus ticks in Central Europe]

Among the various species of hard ticks, Ixodes ricinus is the most frequently found tick throughout Europe. As with other ixodid ticks, the developmental cycle runs through three stages. In each stage a blood meal is required in order to develop to the next stage. Ixodes ricinus has been found to feed on more than 300 different vertebrate species. Usually, larval ticks feed on small mammals such as mice and become infected with various microorganisms and viruses, of which some are substantial pathogens to humans. The pathogens remain in the tick during molting and are thus transstadially transmitted to the next developmental stage. Pathogens transmitted to humans are the agents of Lyme borreliosis, the tick-borne encephalitis virus, Rickettsia species, Anaplasma phagocytophilum, occasionally Francisella tularensis, and protozoal Babesia species. Within the scope of an EU project Ixodes ricinus ticks from all federal states of Austria were searched by means of PCR methods for bacterial pathogens such as Anaplasma phagocytophilum, Borrelia burgdorferi sensu lato, Coxiella burnetii, Ehrlichia spp., Francisella tularensis, Rickettsia spp., and protozoal Babesia. Additionally, the prevalence of Bartonella spp. in this tick species was also determined. Besides the singular detection of Coxiella burnetii and Francisella tularensis in one tick collection site the overall prevalence of Anaplasma phagocytophilum, borreliae, rickettsae and babesiae in Ixodes ricinus amounted to 15%, 14%, 6% and surprising 36% and 51%, respectively. Bartonellae were detected in about 7%.

Antigenic and genomic analysis of a Borrelia burgdorferi sensu stricto strain isolated from Ixodes ricinus ticks in Alto Adige-South Tyrol, Italy

A Borrelia burgdorferi sensu lato strain isolated from IXodes ricinus ticks in Alto Adige-South Tyrol (Northern Italy) was analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) of whole cell proteins, Western immunoblotting analysis (WBA) with polyclonal and monoclonal antibodies, and pulsed-field gel electrophoresis (PFGE). The isolate named BZ6 was identified as belonging to the genospecies B. burgdorferi sensu stricto on the basis of its protein profile and its reactivity with monoclonal and polyclonal antibodies. The PFGE study performed with the two rare-cutting restriction enzymes MluI and SmaI confirmed the SDS-PAGE and WBA characterizations, but showed a genetic diversity between the isolate and two out of the three B. burgdorferi sensu stricto strains used in this study as controls, the American type strain B31 and the locally isolated strain BZ1. No difference in the PFGE patterns between the isolate BZ6 and the Swiss strain IRS was noted. Our findings show the value of PFGE analysis for classifying B. burgdorferi sensu lato isolates and for revealing their genetic diversity, and its usefulness for epidemiological investigations.

Prevalence of Borrelia burgdorferi (sensu lato) in Ixodes ricinus (L.) populations in France, according to a phytoecological zoning of the territory

Ixodes ricinus is considered as the main vector of Lyme Borreliosis in France. The aim of our investigations was to obtain a comprehensive view of the spatial risk linked to the distribution of the species in our country. Previous studies [1] have provided strong evidence that the species populations are widely distributed, so the objective of the present work was to ascertain the bacteriological infection of the tick by the agent of the zoonosis (Borrelia burgdorferi, sensu lato), over the French territory, whatever the ecological conditions may be. For this purpose, we kept the same framework as that used in our acarological investigation, a phytoecological zoning of the territory into 54 geographically separate and ecologically distinct units distributed into three climatic zones. Batches of ticks, picked up in these different phytoecological units (only two thirds of which were sampled), were submitted for bacteriological investigation. A total of 4,673 ticks were examined, individually, for the presence of Borrelia burgdorferi, by immunofluorescence. Percentages of infection according to the various stages of Ixodes ricinus free stages, collected by flagging, were as follows: 4.95% in 3,247 nymphs, 11.2% in 699 males, 12.5% in 727 females. Larvae were ignored. Practically all the tested units harboured the bacterium. The percentage of tick samples (25 ticks or more) absolutely free of Borrelia, wherever they came from, is very low (not exceeding 10 percent of the sampled forests). Our study confirms the assessment of a widespread distribution of the zoonosis in France which was, until now, exclusively based on an approximate distribution of limited human cases observed in the country.

Infection rate of Ixodes ricinus ticks with Borrelia afzelii, Borrelia garinii, and Borrelia burgdorferi sensu stricto in Slovenia

In spring 1993, Ixodes ricinus ticks were collected from six regions of Slovenia to determine their overall rate of infection with Borrelia burgdorferi sensu lato and to assess the frequency of individual species in these tick populations. Ticks were dissected and midgut tissue inoculated into modified Barbour-Stoenner-Kelly (BSK II) medium. Borrelia isolates were differentiated into separate species using species-specific polymerase chain reaction (PCR) primers and by large restriction fragment pattern (LRFP) analysis. Infected ticks were found in all six regions surveyed. Spirochaetes were isolated from 69 of 363 ticks (19%): the isolation rate from adult female ticks was 35% (23/66 ticks cultured), from adult male ticks 22% (20/91), and from nymphal ticks 13% (26/206). Determination of the species of 60 isolates revealed that 32 were Borrelia afzelii (53%), 20 were Borrelia garinii (33%), and 8 were Borrelia burgdorferi sensu stricto (13%). In the Ljubljana region Borrelia afzelii and Borrelia garinii predominated (43% and 40%, respectively), whereas Borrelia burgdorferi sensu stricto constituted only 17% of isolates. In three other regions of the country Borrelia afzelii was isolated exclusively, although the number of isolates investigated was small. This study demonstrates the presence of all three European species of Borrelia burgdorferi sensu lato within the Slovenian tick population and also within a geographic area of less than 100 m2.

Bovine borreliosis: comparison of simple methods for detection of the spirochaete in the blood

Natural Borrelia infection occurring in a calf was followed up using stained blood and buffy coat smears and direct observation of blood and buffy coat in order to compare these spirochaete detection methods. Direct examination of the platelet-plasma interface of the microhaematocrit capillary tubes after centrifugation allowed detection of two parasitaemias that were not seen in Giemsa stained blood smears. An ascending Babesia bigemina infection seemed to suppress the Borrelia parasitaemia. Spirochaetes were detected in five out of 37 Boophilus decoloratus ticks recovered from the infected calf. The blood and the haemolymph stages of Borrelia were measured. After treatment with oxytetracycline the spirochaete could no longer be detected.