Co-exposure to Anaplasma spp., Coxiella burnetii and tick-borne encephalitis virus in sheep in southern Germany

The intracellular bacteria Anaplasma spp. and Coxiella burnetii and the tick-borne encephalitis virus (TBEV) are tick-transmitted pathogens circulating in the southern German sheep population. Knowledge of interaction among Anaplasma spp., C. burnetii and TBEV in sheep is lacking, but together they might promote and reinforce disease progression. The current study aimed to identify co-exposure of sheep to Anaplasma spp., C. burnetii and TBEV. For this purpose, 1,406 serum samples from 36 sheep flocks located in both southern German federal states, Baden-Wuerttemberg and Bavaria, were analysed by ELISAs to determine the antibody levels of the three pathogens. Inconclusive and positive results from the TBEV ELISA were additionally confirmed by a serum neutralisation assay. The proportion of sheep with antibodies against Anaplasma spp. (47.2%), C. burnetii (3.7%) and TBEV (4.7%) differed significantly. Significantly more flocks with Anaplasma spp. seropositive sheep (91.7%) were detected than flocks with antibodies against TBEV (58.3%) and C. burnetii (41.7%), but there was no significant difference between the number of flocks which contained TBEV and C. burnetii seropositive sheep. Seropositivity against at least two pathogens was detected in 4.7% of sheep from 20 flocks. Most co-exposed sheep had antibodies against Anaplasma spp./TBEV (n = 36), followed by Anaplasma spp./C. burnetii (n = 27) and Anaplasma spp./C. burnetii/TBEV (n = 2). Only one sheep showed an immune response against C. burnetii and TBEV. Flocks with sheep being positive against more than one pathogen were widely distributed throughout southern Germany. The descriptive analysis revealed no association between the antibody response of the three pathogens at animal level. Taking the flocks as a cluster variable into account, the exposure to TBEV reduced the probability of identifying C. burnetii antibodies in sheep significantly (odds ratio 0.46; 95% confidence interval 0.24-0.85), but the reason for this is unknown. The presence of Anaplasma spp. antibodies did not influence the detection of antibodies against C. burnetii and TBEV. Studies under controlled conditions are necessary to evaluate any possible adverse impact of co-exposure to tick-borne pathogens on sheep health. This can help to clarify rare disease patterns. Research in this field may also support the One Health approach due to the zoonotic potential of Anaplasma spp., C. burnetii and TBEV.

Molecular detection of Brucella abortus and Brucella melitensis in domestic ruminants and their ticks in selected areas of western Iran

Background

Brucellosis is one of the most important zoonotic diseases caused by Gram-negative bacteria belonging to the genus Brucella. Detection of Brucella species in different countries is of utmost importance.

Aims

This study aimed to detect Brucella abortus and Brucella melitensis in domestic ruminant blood samples and their ticks in western Iran.

Methods

Sampling was conducted on ruminants from August to September 2020 in four different counties of Kurdistan Province, including Divandareh, Marivan, Baneh, and Sanandaj. Totally, 250 blood samples were collected from 250 small ruminants. There were no ticks on the skin of six (2.4%) ruminants, and 244 ticks were isolated from 244 animals. After genomic DNA extraction from all the collected samples, quantitative polymerase chain reaction (qPCR) was performed to detect IS711 gene.

Results

Based on qPCR results, Brucella genus was detected in two blood samples (0.8%) from female sheep and four ticks (1.6%) from male sheep, including three Dermacentor marginatus (1.22%) and one Rhipicephalus turanicus (0.4%). Although B. melitensis was not detected in any tick or blood sample, one tick sample (D. marginatus) was positive for B. abortus.

Conclusion

Considering the positivity of ticks for brucellosis in this study, there is a possibility of Brucella transmission from infected ticks to humans and animals through tick bites, nevertheless, in order to identify the Brucella transmission relationship between ticks and animals, serological tests should be used in future studies.

Update and prognosis of Dermacentor distribution in Germany: Nationwide occurrence of Dermacentor reticulatus

A considerable range expansion of Dermacentor reticulatus has been observed in several European countries, which is concerning in the light of its vector function for several pathogens, including Babesia canis and tick-borne encephalitis virus (TBEV). The present study provides an update on the distribution of Dermacentor ticks in Germany, using a citizen science approach. Ticks were collected by citizens from March 2020 to May 2021, and submitted along with information on the date and location of collection, potential hosts and details about the circumstances of discovery. In total, 3,292 Dermacentor specimens were received, of which 76.4% (2,515/3,292) were identified as D. reticulatus and 23.0% (758/3,292) as D. marginatus, while 0.6% (19/3,292) were too damaged for species-level identification. Dermacentor reticulatus was received from all federal states of Germany. Maxent species distribution models predicted suitable environmental conditions for D. reticulatus throughout Germany. Findings on the vegetation or on pastured animals without travel history confirmed the occurrence of this tick species as far north as the most northern German federal state Schleswig-Holstein. In contrast, the distribution of D. marginatus still appears to be limited to southwestern Germany, although the northward shift of the distribution limit observed in the preceding citizen science study, as compared with previous published distributions, was confirmed. This shift was also predicted by Maxent species distribution models, reflecting the broader distribution of the tick occurrence data contributed by citizens. Most D. reticulatus ticks were found on dogs (1,311/1,960, 66.9%), while D. marginatus was mainly discovered on hoofed animals (197/621, 31.7%) and humans (182/621, 29.3%). Human tick bites were reported in 0.7% (14/1,960) of host-assigned D. reticulatus and 3.4% (21/621) of host-assigned D. marginatus. Further studies to investigate an increasing endemisation of Babesia canis in Germany as well as the relevance of D. reticulatus for TBEV spread throughout the country, e.g., by traveling dogs, are urgently needed. In view of the activity of D. reticulatus during winter or the colder months, which complements that of Ixodes ricinus, a year-round tick protection of at least dogs is strongly recommended.

Anaplasma phagocytophilum and Anaplasma ovis-Emerging Pathogens in the German Sheep Population

Knowledge on the occurrence of pathogenic tick-borne bacteria Anaplasma phagocytophilum and Anaplasma ovis is scarce in sheep from Germany. In 2020, owners from five flocks reported ill thrift lambs and ewes with tick infestation. Out of 67 affected sheep, 55 animals were clinically examined and hematological values, blood chemistry and fecal examinations were performed to investigate the underlying disease causes. Serological tests (cELISA, IFAT) and qPCR were applied to all affected sheep to rule out A. phagocytophilum and A. ovis as a differential diagnosis. Ticks were collected from selected pastures and tested by qPCR. Most animals (n = 43) suffered from selenium deficiency and endoparasites were detected in each flock. Anaplasma spp. antibodies were determined in 59% of examined sheep. Seventeen animals tested positive for A. phagocytophilum by qPCR from all flocks and A. phagocytophilum was also detected in eight pools of Ixodes ricinus. Anaplasma phagocytophilum isolates from sheep and ticks were genotyped using three genes (16S rRNA, msp4 and groEL). Anaplasma ovis DNA was identified in six animals from one flock. Clinical, hematological and biochemical changes were not significantly associated with Anaplasma spp. infection. The 16S rRNA analysis revealed known variants of A. phagocytophilum, whereas the msp4 and groEL showed new genotypes. Further investigations are necessary to evaluate the dissemination and health impact of both pathogens in the German sheep population particularly in case of comorbidities.

Scalp eschar and neck lymphadenopathy by Rickettsia slovaca after Dermacentor marginatus tick bite case report: multidisciplinary approach to a tick-borne disease

BACKGROUND

Scalp Eschar and Neck LymphAdenopathy after Tick bite is a zoonotic non-pathogen-specific disease most commonly due to Rickettsia slovaca and Rickettsia raoultii. Diagnosis is mostly based only on epidemiological and clinical findings, without serological or molecular corroboration. We presented a clinical case in which diagnosis was supported by entomological identification and by R. slovaca DNA amplifications from the tick vector.

CASE PRESENTATION

A 6-year-old child presented with asthenia, scalp eschar and supraclavicular and lateral-cervical lymphadenopathy. Scalp Eschar and Neck LymphAdenopathy After Tick bite syndrome following a Dermacentor marginatus bite was diagnosed. Serological test on serum revealed an IgG titer of 1:1024 against spotted fever group rickettsiae, polymerase chain reaction assays on tick identified Rickettsia slovaca. Patient was successfully treated with doxycycline for 10 days.

CONCLUSIONS

A multidisciplinary approach including epidemiological information, clinical evaluations, entomological identification and molecular investigations on tick, enabled proper diagnosis and therapy.

Spotted fever group rickettsiae transmitted by Dermacentor ticks and determinants of their spread in Europe

Rickettsiae from the spotted fever group, i.e. the etiological agents of tick-borne lymphadenopathy/Dermacentor-borne necrotic erythema and lymphadenopathy (TIBOLA /DEBONEL) syndrome, are associated with ticks, including Dermacentor marginatus and Dermacentor reticulatus. The expansion of these ticks into new areas increases the risk of infection of their hosts with tick-borne pathogens. The study summarises the importance of 2 species from the genus Dermacentor, i.e. D. marginatus and D. reticulatus, in the spread of spotted fever group rickettsiae in various regions of Europe. The study also focuses on the determinants of the presence of vectors and transmission of rickettsiae, as well as the effects of human infections with these pathogens. The climate changes observed nowadays affect vectors and increase the incidence and spread of tick-borne diseases worldwide. Due to the existing risk of exposure to an increasing number of people, knowledge about the course of these serious diseases and their etiological factors should be disseminated among healthcare professionals as well as in society. There is a great challenge for epidemiological services to provide access to medical and veterinary facilities in order to diagnose and treat rickettsioses. Therefore, the development of a strategy for tick control and the popularisation of knowledge concerning prophylaxis of tick-borne diseases is indispensable.

De novo assembly and analysis of the transcriptome of the Dermacentor marginatus genes differentially expressed after blood-feeding and long-term starvation

Background

The ixodid tick Dermacentor marginatus is a vector of many pathogens wide spread in Eurasia. Studies of gene sequence on many tick species have greatly increased the information on tick protective antigen which might have the potential to function as effective vaccine candidates or drug targets for eco-friendly acaricide development. In the current study, RNA-seq was applied to identify D. marginatus sequences and analyze differentially expressed unigenes.

Methods

To obtain a broader picture of gene sequences and changes in expression level, RNA-seq was performed to obtain the whole-body transcriptome data of D. marginatus adult female ticks after engorgement and long-term starvation. Subsequently, the real-time quantitative PCR (RT-qPCR) was applied to validate the RNA-seq data.

Results

RNA-seq produced 30,251 unigenes, of which 32% were annotated. Gene expression was compared among groups that differed by status as newly molted, starved and engorged female adult ticks. Nearly one third of the unigenes in each group were differentially expressed compared to the other two groups, and the most numerous were genes encoding proteins involved in catalytic and binding activities and apoptosis. Selected up-regulated differentially expressed genes in each group were associated to protein, lipids, carbohydrate and chitin metabolism. Blood-feeding and long-term starvation also caused genes differentially expressed in the defense response and antioxidant response. RT-qPCR results indicated 6 differentially expressed transcripts showed similar trends in expression changes with RNA-seq results confirming that the gene expression profiles in transcriptome data is in consistent with RT-qPCR validation.

Conclusions

Obtaining the sequence information of D. marginatus and characterizing the expression pattern of the genes involved in blood-feeding and during starvation would be helpful in understanding molecular physiology of D. marginatus and provides data for anti-tick vaccine and drug development for controlling the tick.

Dermacentor marginatus and Dermacentor reticulatus, and Their Infection by SFG Rickettsiae and Francisella-Like Endosymbionts, in Mountain and Periurban Habitats of Northwestern Italy

We investigated the distribution of Dermacentor spp. and their infection by zoonotic bacteria causing SENLAT (scalp eschar neck lymphadenopathy) in Turin province, northwestern Italy. We collected ticks in a mountain and in a periurban park, from vegetation and different animal sources, and we sampled tissues from wild boar. Dermacentor marginatus (n = 121) was collected in both study areas, on vegetation, humans, and animals, while D. reticulatus (n = 13) was exclusively collected on wild boar from the periurban area. Rickettsia slovaca and Candidatus Rickettsia rioja infected 53.1% of the ticks, and R. slovaca was also identified in 11.3% of wild boar tissues. Bartonella spp. and Francisella tularensis were not detected, however, Francisella-like endosymbionts infected both tick species (9.2%). Our findings provide new insights on the current distribution of Dermacentor spp. and their infection with a spotted-fever group rickettsiae in the Alps region. Wild boar seem to play a major role in their eco-epidemiology and dispersion in the study area. Although further studies are needed to assess the burden of rickettsial diseases, our results highlight the risk of contracting SENLAT infection through Dermacentor spp. bites in the region.

Spotted fever group rickettsiae in Dermacentor marginatus from wild boars in Italy

Following the increase in wild boar population recorded in urban and peri-urban areas throughout Europe, the present survey aimed to assess the occurrence of zoonotic tick-borne pathogens (TBPs) in wild boars living in southern Italy and in their ticks for evaluating the potential risk of infection for animals and humans. From October to December 2019, a total of 176 ticks collected from 93 wild boars andtheir spleen samples were molecularly screened for selected TBPs. Overall, all the wild boars were infested by ticks (mean intensity, 1.9) with Dermacentor marginatus and Ixodes ricinus being identified in 99.4% and 0.6%, respectively. Out of 93 wild boars, 17 (18.3%) were infested by ticks which scored positive to spotted fever group (SFG) Rickettsia species. Rickettsia slovaca and Rickettsia raoultii were identified in 16 (9%) and 1 (0.6%) D. marginatus, respectively, whereas a single I. ricinus (0.6%) was infected by R. slovaca. A single wild boar (1.1%) tested positive to R. slovaca. All ticks and wild boars scored negative to Babesia/Theileria spp., Ehrlichia spp., Anaplasma spp., Candidatus Neoehrlichia spp., Coxiella burnetii and Borrelia burgdorferi sensu lato complex. Data herein obtained suggest that wild boars are involved in the maintenance of D. marginatus in the environment as in peri-urban areas herein investigated. An integrated management approach is advocated for wild boar population control and in preventing the potential risk of TBPs infection in animals and humans.

Vectors, molecular epidemiology and phylogeny of TBEV in Kazakhstan and central Asia

BACKGROUND

In the South of Kazakhstan, Almaty Oblast' (region) is endemic for tick-borne encephalitis, with 0.16-0.32 cases/100,000 population between 2016-2018. The purpose of this study was to determine the prevalence and circulating subtypes of tick-borne encephalitis virus (TBEV) in Almaty Oblast' and Kyzylorda Oblast'.

METHODS

In 2015 we investigated 2341 ticks from 7 sampling sites for the presence of TBEV. Ticks were pooled in 501 pools and isolated RNA was tested for the presence of TBEV by RT-qPCR. For the positive samples, the E gene was amplified, sequenced and a phylogenetic analysis was carried out.

RESULTS

A total of 48 pools were TBEV-positive by the RT-qPCR. TBEV-positive ticks were only detected in three districts of Almaty Oblast' and not in Kyzylorda Oblast'. The positive TBEV pools were found within Ixodes persulcatus, Haemaphysalis punctata and Dermacentor marginatus. These tick species prevailed only in Almaty Oblast' whereas in Kyzylorda Oblast' Hyalomma asiaticum and D. marginatus are endemic. The minimum infection rates (MIR) in the sampling sites were 4.4% in Talgar, 2.8% in Tekeli and 1.1% in Yenbekshikazakh, respectively. The phylogenetic analysis of the generated sequences indicates that TBEV strains found in Almaty Oblast' clusters in the Siberian subtype within two different clades.

CONCLUSIONS

We provided new data about the TBEV MIR in ticks in Almaty Oblast' and showed that TBEV clusters in the Siberian Subtype in two different clusters at the nucleotide level. These results indicate that there are different influences on the circulating TBEV strains in south-eastern Kazakhstan. These influences might be caused by different routes of the virus spread in ticks which might bring different genetic TBEV lineages to Kazakhstan. The new data about the virus distribution and vectors provided here will contribute to an improvement of monitoring of tick-borne infections and timely anti-epidemic measures in Kazakhstan.

Sequence identification and expression profile of seven Dermacentor marginatus glutathione S-transferase genes

Dermacentor marginatus is a widespread tick species and a vector of many pathogens in Eurasia. Due to the medical importance of D. marginatus, control measures are needed for this tick species. Currently tick control approaches rely mostly on acaricide application, whereas wrong and irrational acaricide use may result in drug resistance and residue problems. Vaccination as an alternative approach for tick control has been proven to be effective towards some tick species. However, immunization against D. marginatus has not yet reached satisfactory protection. The effort of in silico based analysis could predict antigenicity and identify candidates for anti-tick vaccine development. We carried out an in silico analysis of D. marginatus glutathione S-transferases (DmGSTs) in order to identify blood-feeding induced GSTs as antigens that can be used in anti-tick vaccine development. Phylogenetic analysis, linear B-cell epitope prediction, homology modeling, and conformational B-cell epitope mapping on the GST models were performed to identify highly antigenic DmGSTs. Relative gene expressions of the seven GSTs were profiled through real-time quantitative PCR (RT-qPCR) to outline GSTs up-regulated during blood feeding. The phylogenetic analysis indicated that the seven GSTs belonged to four classes of GST, including one in epsilon-class, one in zeta-class, one in omega-class, and four in mu-class. Linear B-cell epitope prediction revealed mu-class GSTs share similar conserved antigenic regions. The conformational B-cell epitope mapped on the homology model of the GSTs displayed that GSTs of mu-class showed stronger antigenicity than that of other classes. RT-qPCR revealed DmGSTM1 and DmGSTM2 were positively related to blood feeding. In sum, the data suggest that DmGSTM1 and DmGSTM2 could be tested for potential anti-tick vaccine trials.

The Spatial Distribution of Dermacentor Ticks (Ixodidae) in Germany-Evidence of a Continuing Spread of Dermacentor reticulatus

In Europe, two tick species of the genus Dermacentor occur, Dermacentor marginatus and Dermacentor reticulatus. When the spatial distribution of both species in Germany was studied comprehensively for the first time in 1976, D. marginatus populations were recorded along the Rhine and Main river valleys in southwestern Germany, while D. reticulatus was very rare. In the last 50 years, however, a considerable range expansion of D. reticulatus has been noted in several European countries. To assess the current distribution of Dermacentor spp. in Germany, citizens were asked to send in ticks suspected to belong to the genus Dermacentor or that were of “unusual” appearance. From February 2019 until February 2020, 3,902 Dermacentor ticks were received in total. Of those, 15.48% (604/3,902) were identified as D. marginatus and 84.24% (3,287/3,902) as D. reticulatus, while 11 specimens could not be identified to species level. The majority of D. reticulatus specimens was collected from dogs (1,212/2,535; 47.12%), while D. marginatus was mostly collected from horses (184/526; 34.98%). Our results confirm that the adults of both Dermacentor species are active all year round. D. reticulatus specimens were sent in from all federal states except the Free and Hanseatic City of Hamburg, while D. marginatus specimens were only received from locations in southwestern Germany. Overall, data obtained from this citizen-science study show that D. reticulatus has significantly expanded its range, especially in northern Germany. Regarding D. marginatus, new locations northwest of the previous range were detected, although the distribution has remained rather stable as compared to D. reticulatus. The spread of D. reticulatus, the vector of Babesia canis, is of major importance for veterinarians and dog owners in terms of canine babesiosis outbreaks or endemization in hitherto B. canis-free areas. Thus, veterinarians and veterinary students need to be informed about the new situation to be able to give adequate advice to dog owners on the extended D. reticulatus range and appropriate control measures.

Caracterization of glutathione S-transferase of Dermacantor marginatus and effect of the recombinant antigen as a potential anti-tick vaccine

Dermacentor marginatus is one of the main tick species in northwestern China, and is a vector of various tick-borne pathogens. Tick control method largely depends on chemical agents, but the disadvantages of using such approach would cause environmental damage and the risk of developing tick resistance to acaricides. Vaccination of tick protective antigen is an eco-friendly approach which is an alternative and promising method to mitigate tick infestation in livestock. In the study, a mu-class glutathione S-transferase (GST) sequence of D. marginatus was cloned and the recombinant protein (rDmGST) was expressed. Transcriptional level of the GST was measured together with native GST activity of the tick. Finally, A vaccine trial on rabbits against D. marginatus was proceeded to evaluate the anti-tick effect of rDmGST. Results reveled that the CDs of the D. margiantus glutathione S-transferase mu 1 gene has 669 base pair nucleotide sequence encoding a 223 amino acid. The deduced GST protein sequence had over 95 % similarity with that of D. variabilis. The rDmGST was efficiently expressed soluble and purified by His trap affinity chromatography. Enzyme activity of native GST and transcriptional profiles of the GST showed up-regulation in different stages and organs of D. marginaus during blood feeding. Polyclonal antibody reacted with rDmGST in Western blotting. Tick challenge on rDmGST inoculated rabbits showed reductions in adult female engorgement rate, total egg mass and egg hatching rate with an overall vaccine efficacy of 43.69 %. The results of the experiment indicated the GST has potential value to be an effective protective antigen of D. marginatus.

The mitochondrial genome of the ornate sheep tick, Dermacentor marginatus

The ornate sheep tick, Dermacentor marginatus, is widespread in Europe. Its vector role of various zoonotic pathogens received much attention in these regions. However, the genomic resources of the ticks are limited. In this study, the complete mitochondrial genome of a single female D. marginatus collected in Slovakia was sequenced through the Illumina HiSeq sequencing platform. The mitochondrial genome is 15,067 bp long and contains 13 protein-coding genes, two ribosomal RNA genes and 22 transfer RNA genes. The overall G+C content is 21.6%. The gene order is identical to that of Metastriata ticks. The codon usage pattern is similar with that of other tick species. As in other ticks, two truncated tRNA genes were observed. Two control regions were found between tRNA-Leu and tRNA-Cys, tRNA-Ile and rrnS, respectively. The mitochondrial genome contains three noncoding regions, which is similar to that in D. nitens. The noncoding region located between rrnS and tRNA-Val is shorter than that of other Dermacentor species. Phylogenetic analyses indicate that D. marginatus is clustered with other Dermacentor species. These findings are helpful for exploring the systematics and evolution of ticks in the future.

Molecular investigation of the natural transovarial transmission of tick-borne pathogens in Turkey

This study aimed to investigate the presence of the natural transovarial transmission of tick-borne pathogens in unfed larvae obtained from engorged female ticks from domestic animals in Turkey. Larvae (n = 4530, 151 pools) obtained from 75 engorged female ticks and female carcasses were screened for the presence of certain tick-borne pathogens by PCR. The presence of transovarial transmission of Babesia occultans was detected in Hyalomma marginatum and Hy. excavatum, while Ba. ovis in Rhipicephalus bursa. Theileria annulata was detected only in Hy. excavatum and Rh. turanicus female carcasses, but not in their examined progenies. Additionally, Rickettsia aeschlimannii and Rickettsia raoultii were detected in Hy. marginatum and Dermacentor marginatus females, respectively, and all their examined larvae. Besides, Ri. slovaca was detected in a De. marginatus female carcass and its one of two examined larvae pools. The presence of mixed Ba. occultans and Ri. aeschlimannii infection was also determined in an Hy. marginatum female and its larvae. This is the first demonstration of transovarial transmission of Ba. occultans in naturally infected Hy. excavatum. These data suggested that Hy. excavatum may act as vector in the natural cycle of Ba. occultans.

The bacterial microbiome of field-collected Dermacentor marginatus and Dermacentor reticulatus from Slovakia

Background

The important roles of microbial flora in tick biology and ecology have received much attention. Dermacentor marginatus and Dermacentor reticulatus are known vectors of various pathogens across Europe, including Slovakia. However, their bacterial microbiomes are poorly explored.

Methods

In this study, bacterial microbiomes of field-collected D. marginatus and D. reticulatus from Slovakia were characterized using 16S rRNA high-throughput sequencing.

Results

Different analyses demonstrated that the D. marginatus and D. reticulatus microbiomes differ in their diversity and taxonomic structures. Furthermore, species- and sex-specific bacteria were detected in the two species. A possible bacterial pathogen “Candidatus Rhabdochlamydia sp.” was detected from D. marginatus males. Among the observed bacteria, Rickettsia showed high abundance in the two species. Several maternally inherited bacteria such as Coxiella, Arsenophonus, Spiroplasma, Francisella and Rickettsiella, were abundant, and their relative abundance varied depending on tick species and sex, suggesting their biological roles in the two species.

Conclusions

The bacterial microbiomes of field-collected D. marginatus and D. reticulatus were shaped by tick phylogeny and sex. Maternally inherited bacteria were abundant in the two species. These findings are valuable for understanding tick-bacteria interactions, biology and vector competence of ticks.

Electronic supplementary material

The online version of this article (10.1186/s13071-019-3582-9) contains supplementary material, which is available to authorized users.

Analysis of the environmental and host-related factors affecting the distribution of the tick Dermacentor marginatus

Understanding and responding to the ecological, social and economic conditions that facilitate disease emergence and transmission represents a substantial challenge for epidemiologists and health professionals. In this article we integrate knowledge about the human and the vector population, to provide a context from which to examine the underlying causal factors of D. marginatus-borne diseases emergence in the study area. Within this framework we analyse the biotic and abiotic factors that drive D. marginatus population dynamics and the role of its typical host for dispersal. These investigations suggest that D. marginatus is a tick species prone to spatially overlap its presence with human population presence. Then we consider the public health implications for the residents, when simply carrying out trivial outdoor activities may increase the risk to contact an infected tick.

Brucella melitensis and B. abortus in eggs, larvae and engorged females of Dermacentor marginatus

Brucellosis is a relatively common zoonosis, particularly in the developing countries. Our aim was to cultivate the Brucella wild-type strain from eggs of Dermacentor marginatus, and to molecularly investigate the presence of Brucella DNA in different developmental stages. A total of 350 engorged adult female ticks were collected from sheep and cattle, and individually placed into a single clean breathable tube suitable for laying eggs and for the development of larvae. Detection of Brucella DNA was attempted in engorged female ticks and their offsprings based on the Brucella outer membrane protein gene 22 (omp22) and IS711 gene. Additionally, bacterial isolation in the culture medium of Brucella was performed. The eggs from the Brucella DNA-positive engorged female ticks were positive for Brucella omp22 (4.6%, 16/350). The prevalence was 40.9% (90/220) in larvae, which developed from the Brucella DNA-positive egg batch. Based on BLASTn analysis of IS711 gene, ten (4.1%, 10/242) PCR products were identified as Brucella melitensis in D. marginatus from sheep, while six (5.6%, 6/108) were identified as B. abortus in D. marginatus infesting cattle. B. melitensis biotype 3 was isolated from eggs of D. marginatus. This is the first study which demonstrates the transovarial transmission of Brucella in the D. marginatus. Furthermore, Brucella may be partially transmitted from D. marginatus eggs to larvae (40.9%) in D. marginatus. These findings extend our knowledge on the transmission of Brucella in D. marginatus offsprings.

Crimean-Congo Hemorrhagic Fever Virus and Borrelia burgdorferi sensu lato in Ticks from Kosovo and Albania

Tick-borne diseases pose a serious threat to human health in South-Eastern Europe, including Kosovo. While Crimean–Congo hemorrhagic fever (CCHF) is a well-known emerging infection in this area, there are no accurate data on Lyme borreliosis and tick-borne encephalitis (TBE). Therefore, we sampled and tested 795 ticks. Ixodes ricinus (n = 218), Dermacentor marginatus (n = 98), and Haemaphysalis spp. (n = 24) were collected from the environment by flagging (all from Kosovo), while Hyalomma marginatum (n = 199 from Kosovo, all from Kosovo) and Rhipicephalus bursa (n = 130, 126 from Albania) could be collected only by removal from animal pasture and domestic ruminants. Ticks were collected in the years 2014/2015 and tested for viral RNA of CCHF and TBE viruses, as well as for DNA of Borrelia burgdorferi sensu lato by real-time PCR. In Kosovo, nine ticks were positive for RNA of Crimean–Congo hemorrhagic fever virus and seven for DNA of B. burgdorferi s. l. None of the ticks tested positive for TBEV. CCHF virus was detected in one H. marginatum male specimen collected while feeding on grazing cattle from the Prizren region and in eight R. bursa specimens (five females and three males collected while feeding on grazing sheep and cattle) from the Prishtina region (Kosovo). B. burgdorferi s. l. was detected in seven questing ticks (four male and one female D. marginatus, two I. ricinus one female and one male) from the Mitrovica region (Kosovo). Our study confirmed that CCHF virus is circulating in Kosovo mainly in H. marginatum and R. bursa in the central areas of the country. B. burgdorferi s. l. was found in its major European host tick, I. ricinus, but also in D. marginatus, in the north of the Kosovo. In order to prevent the spread of these diseases and better control of the tick-borne infections, an improved vector surveillance and testing of ticks for the presence of pathogens needs to be established.

Rickettsia spp. in Dermacentor marginatus ticks: analysis of the host-vector-pathogen interactions in a northern Mediterranean area

In this work, we have analyzed the key features of Rickettsia spp. maintenance in Dermacentor marginatus ticks in four regions of the northern Mediterranean area, where extensive investigations are currently lacking. For this purpose, 380 adult D. marginatus ticks were collected from vegetation and wild ungulates during a 3-year study. A host-vector-pathogen interaction approach was applied to investigate the key components of the disease systems and evaluate their respective weight in the intensity of infection in natural foci. A high variability in the R. slovaca infection rate among sampling sites was observed, whereas R. raoultii was sporadically present and at low infection rates. Dermacentor marginatus presence was confirmed in all the investigated regions. The local wild boar population showed a strong association with adult D. marginatus ticks. The results of this investigation suggest that wild boars not only maintain D. marginatus populations by feeding adult ticks, but may also have a potential role in the eco-epidemiology of rickettsioses, as carriers of rickettsiae-infected ticks. The public health implications of these results are discussed.

Presence of host-seeking Ixodes ricinus and their infection with Borrelia burgdorferi sensu lato in the Northern Apennines, Italy

Host-seeking ticks were collected in the Northern Apennines, Italy, by dragging at 35 sites, at altitudes ranging from 680 and 1670 m above sea level (asl), from April to November, in 2010 and 2011. Ixodes ricinus (4431 larvae, 597 nymphs and 12 adults) and Haemaphysalis punctata (11,209 larvae, 313 nymphs, and 25 adults) were the most abundant species, followed by Haemaphysalis sulcata (20 larvae, five nymphs, and 13 adults), Dermacentor marginatus (42 larvae and two adults) and Ixodes hexagonus (one nymph). Greatest numbers of ticks were collected at locations characterised by southern exposure and limestone substratum, at altitudes <1400 m asl; I. ricinus was most abundant in Turkey oak (Quercus cerris) wood, whereas H. punctata was mostly collected in hop hornbeam (Ostrya carpinifolia) wood and on exposed rocks. Ixodes ricinus was also found up to 1670 m asl, in high stand beech (Fagus sylvatica) wood. The overall prevalence of Borrelia burgdorferi sensu lato (sl) in 294 host-seeking I. ricinus nymphs was 8.5 %. Borrelia garinii was the most frequently identified genospecies (64.0 % of positive nymphs), followed by B. valaisiana, B. burgdorferi sensu stricto, B. afzelii, and B. lusitaniae. Based upon the comparison with the results of previous studies at the same location, these research findings suggest the recent invasion of the study area by the tick vector and the agents of Lyme borreliosis.

Long term study of ixodid ticks feeding on red deer (Cervus elaphus) in a meso-Mediterranean climate

Red deer (Cervus elaphus L.) are very valuable in trophy-hunting but also contribute to the preservation of natural areas. They are affected by many parasites and pathogens, including hard ticks that are not only important parasites themselves but can also act as vectors and/or reservoirs of pathogens. Tick phenology is complex insofar as population dynamics depend on environmental conditions, vegetation, host availability and their own intrinsic characteristic. Ticks were collected monthly from January 2007 to December 2014 from red deer on a natural reserve located in a meso-Mediterranean environment in Central Spain. A total of 8978 specimens of ixodid ticks were recovered with a mean Parasitization Index of 65.06 ticks/deer. Red deer were infected the whole year round with a summer-spring pattern and two secondary peaks in February and October. The main species was Hyalomma lusitanicum Koch followed by Rhipicephalus bursa Canestrini and Fanzago, Rhipicephalus pusillus Gil Collado, Dermacentor marginatus Sulzer and Ixodes ricinus L. Hyalomma lusitanicum has a complex life cycle in which several generations initiate their cycle at different times throughout the year, most probably lasting more than 1 year. We also describe the ability of nymphs to feed on large ungulates even though their habitual host is wild rabbit.

Isolation and maintenance of Rickettsia raoultii in a Rhipicephalus sanguineus tick cell line

Rickettsia raoultii, a member of the spotted fever group rickettsiae, has been implicated in cases of DEBONEL/TIBOLA/SENLAT, and has been detected in Dermacentor spp. and Rhipicephalus pumilio ticks by PCR. R. raoultii has been isolated in mammalian and tick cell lines. This study aimed to isolate R. raoultii from Spanish Dermacentor marginatus in tick cell lines. A single adult D. marginatus collected from vegetation in La Rioja (Northen Spain) in October 2012 was surface-sterilised, triturated and aliquots of the homogenate were inoculated into a panel of tick cell lines derived from embryonic Rhipicephalus sanguineus, Rhipicephalus evertsi and Ixodes ricinus. Cultures were maintained at 28 °C with weekly medium changes and checked by Gimenez stain for Rickettsia-like intracellular organisms. After 50 days of incubation, intracellular Rickettsia-like organisms were observed in the R. sanguineus cell line RML-RSE using Gimenez stain. PCR assays and sequencing of fragments of 16S RNA, ompB and ompA genes in DNA extracted from the culture suspension showed 100% identity with R. raoultii. Growth of intracellular microorganisms was not observed in preparations of the other tick cell lines. In conclusion, the tick cell line RML-RSE is a useful system for the isolation and maintenance of R. raoultii.

Environmental Monitoring and Surveillance of Rodents and Vectors for Francisella tularensis Following Outbreaks of Human Tularemia in Georgia

Tularemia is a re-emerging bacterial zoonosis, broadly distributed across the northern hemisphere. In Georgia, there is a history of human tularemia outbreaks dating back to the 1940s. In response to outbreaks, health officials initiated long-term field surveillance and environmental monitoring. The objective of our study was to obtain information from 57 years of field surveys to identify species that play a role in the occurrence Francisella tularensis subsp. holarctica in the environment in Georgia. We collected historical data on human outbreaks, field collections, population dynamics of the common vole (Microtus arvalis), and conducted surveys on small mammals and vectors from five regions in Georgia during 1956-2012. Bacterial isolation was conducted using standard culturing techniques, and isolation rates for species were obtained for a subset of years. We used a Spearman rank correlation to test for associations between the density of the common vole and isolation rates. From 1956 through 2012, there were four recorded outbreaks of human tularemia (362 cases). A total of 465 bacterial isolates of F. tularensis subsp. holarctica were obtained from 27 species and environmental samples. The number of isolations was highest in the common vole (M. arvalis; 149 isolates; 32%) and Dermacentor marginatus ticks (132 isolates; 28%); isolation rates ranged between 0-0.91% and 0-0.47%, respectively. Population dynamics of the common vole were not correlated with the isolation rate. Given the history of tularemia re-emergence in Georgia, continued field surveys and environmental monitoring may provide an early indication of outbreak risk in humans. In conclusion, our findings provide evidence of long-standing foci of F. tularensis subsp. holarctica that are likely maintained by the common vole-tick cycle.

Defensin from the ornate sheep tick Dermacentor marginatus and its effect on Lyme borreliosis spirochetes

Expression of the previously reported defensin of the tick Dermacentor marginatus (defDM) was analysed in different organs by RT-PCR. mRNA of the defDM gene was detected in the hemolymph, midgut and salivary glands. Moreover defDM was isolated from the tick hemolymph using RP-HPLC and its sequence was determined by mass spectrometry and Edman degradation. Synthetic peptide was used for determining biological activities. The results showed an anti-Gram-positive bacterial role for the defensin. As D. marginatus ticks appear not to be vectors of the Lyme disease agent of the complex Borrelia burgdorferi sensu lato, we tested the influence of defDM on Borrelia afzelii. There is a very clear borrelicidal activity of the defensin, which is concentration dependent and suggests a possible role in the clearing of Borrelia ingested by D. marginatus ticks.

Seasonal dynamics of tick species in an urban park of Rome

Regular collections were obtained in the Natural Reserve of the Insugherata of Rome during 2011 in order to obtain the tick species composition and the respective seasonal dynamics of the area. A total of 325 ticks was collected in selected sites by means of drag sampling. Among the identified species, Rhipicephalus turanicus was the most abundant (72.3%), followed by Ixodes ricinus (19.7%), Dermacentor marginatus (6.5%), Haemaphysalis punctata (1.2%), and Rhipicephalus bursa (0.3%). R. turanicus occurred mainly in pastures, showing a mono-modal seasonal activity pattern from spring to early summer. Questing I. ricinus were prevalent in woodland from October to May, and the seasonal trend of specimens showed a weak peak in winter. Although adult D. marginatus exhibited seasonal dynamics similar to I. ricinus, with an activity period from October to April, this species occurred in a different environment (pasture) and with considerably lower densities. Haemaphysalis punctata and R. bursa were rare, with an apparent autumn and autumn-winter seasonal activity, respectively. While the species diversity recorded appears as an unequivocal consequence of the natural state of the park, the remarkable R. turanicus density could be a direct effect of the recent introduction of wild boar, as carriers, from the close Veio Park. The presence of the species, a proven vector of various diseases in humans and domestic animals, is discussed in the light of the possible risk of tick-bite exposure of park workers and visitors.

Rickettsia slovaca in immature Dermacentor marginatus and tissues from Apodemus spp. in the northern Apennines, Italy

Immature Dermacentor marginatus ticks and tissues from small rodents were tested for infection with Rickettsia slovaca in the northern Apennines, Lucca Province, where tick-borne lymphadenopathy (TIBOLA) was previously reported in people. Prevalence of infestation with D. marginatus was 30.5% (n=131, 95% CI: 22.8-39.2%) in Apodemus spp. and 26.5% (n=34, 95% CI: 12.9-44.4%) in Myodes glareolus, which were captured during 1980 trap nights in 2009 and 2010. Rickettsia slovaca was identified by polymerase chain reaction, targeting the gltA and OmpA genes, in ear biopsies from 8 out of 37 tested Apodemus (22%, 95% CI: 9.8-38.2%), but not from 9 M. glareolus. The prevalence of R. slovaca in D. marginatus feeding on Apodemus spp. was 53% in larvae (n=51, 95% CI: 38.5-67.1%) and 47.5% in nymphs (n=59, 95% CI: 34.3-60.9%). No larvae (0.0%, 95% CI: 0-36.9%), but one nymph removed from M. glareolus was positive (10%, 95% CI: 0.3-44.5%). Prevalence of R. slovaca in host-seeking D. marginatus larvae, collected in the same area, was 42% (n=38; 95% CI: 26.3-59.2%). Prevalence of R. slovaca was greater in larvae feeding on PCR-positive Apodemus than in those feeding on negative mice (78.6% vs. 37.1%). Furthermore, levels of infestation with D. marginatus larvae were greater for R. slovaca-positive mice. The infection of Apodemus spp. was probably the result of repeated bites by transovarially infected larvae. On the other hand, the finding of R. slovaca in mice tissues would be compatible with transmission from these hosts to feeding D. marginatus. Based on such a hypothesis, the most heavily infested Apodemus might play a role as amplifiers of the infection.