Rickettsia slovaca and Rickettsia raoultii in Dermacentor marginatus and Dermacentor reticulatus ticks from Slovak Republic

First records of Secretargas transgariepinus (Argasidae) in Libya and Jordan: corrections of collection records and detection of microorganisms

The primarily bat-associated argasid tick, Secretargas transgariepinus (White, 1846), is a member of the Afrotropical and southern Palaearctic fauna. Probably because of its secretive life style, little is known about this species and records of its collection are scant. Based on morphological revisions of the available specimens, we report new Middle Eastern records for this tick species that had been misidentified as other bat-associated argasid taxa. These specimens are larvae from three localities, and represent the first records of S. transgariepinus from two countries: one larva from Sabratha (Libya) was collected from an unidentified bat species (possibly Eptesicus isabellinus), seven larvae from Azraq-Shishan (Jordan), and 78 larvae from Shamwari (Jordan) were all collected from Otonycteris hemprichii. Twenty larvae from Shamwari were also tested for the presence of both, viral or bacterial microorganisms by PCR. Three ticks were found to be infected with the Murid gammaherpesvirus 68 (MHV-68), one with Borrelia burgdorferi sensu lato, and four with a Rickettsia sp. closely related to Rickettsia slovaca. The findings represent a first evidence for the occurrence of these possible pathogens in S. transgariepinus.

Detection of Rickettsia raoultii in Vermipsylla alakurt-Like Fleas of Sheep in Northwestern China

INTRODUCTION

To date, a total of 2574 validated flea species have been discovered. Vermipsyllidae is a family of fleas that comprises at least eight species. Vermipsylla is a genus of the family Vermipsyllidae within the order Siphonaptera of fleas. Here a novel Vermipsylla species was described, and rickettsial agent was also detected in it.

METHODS

A total of 128 fleas were collected directly from 260 pastured sheep in China. Of these, eight representative fleas (four males and four females) were identified by key morphological features. Meanwhile, 120 flea DNAs, including six flea samples for molecular taxonomy, were subjected to Rickettsia spp. DNA detection. The molecular identity of fleas was determined by amplification and sequenmce analysis of four genetic markers (the 28S rDNA genes, the 18S rDNA genes, the mitochondrial cytochrome c oxidase subunit I and subunit II). In addition, five Rickettsia-specific gene fragments were used to identify the species of the rickettsial agents. The amplified products were sequenced and phylogenetically analyzed.

RESULTS

The morphological characteristics of the flea species identified in this study were similar to Vermipsylla alakurt, but presented difference in hair number of the metepimeron, the third tergum, the genitals and the tibiae of hind leg. The 18S rDNA, 28S rDNA and COII genetic markers from fleas showed the highest identity to those of V. alakurt, shared 98.45% (954/969), 95.81% (892/931) and 85.86% (571/665) similarities, respectively. However, the COI sequence showed the highest identity to that of Dorcadia ioffi with 88.48% (576/651) similarity. Rickettsia raoutii tested positive in 14.17% (17/120) flea DNA samples.

CONCLUSION

Our study reports the detection of R. raoultii in V. alakurt-like fleas infesting sheep in China.

Molecular Survey of Rickettsia raoultii in Ticks Infesting Livestock from Pakistan with Notes on Pathogen Distribution in Palearctic and Oriental Regions

Ticks are hematophagous ectoparasites that transmit different pathogens such as Rickettsia spp. to domestic and wild animals as well as humans. Genetic characterizations of Rickettsia spp. from different regions of Pakistan are mostly based on one or two genetic markers and are confined to small sampling areas and limited host ranges. Therefore, this study aimed to molecularly screen and genetically characterize Rickettsia spp. in various tick species infesting camels, sheep, and goats. All the collected tick specimens were morphologically identified, and randomly selected tick species (148) were screened molecularly for the detection of Rickettsia spp. by amplifying three rickettsial DNA fragments, namely, the citrate-synthase gene (gltA), outer-membrane protein A (ompA), and outer-membrane protein B (ompB). After examining 261 hosts, 161 (61.7%) hosts were found infested by 564 ticks, including 287 (50.9%) nymphs, 171 (30.3%) females, and 106 (18.8%) males in five districts (Kohat, Dera Ismail Khan, Lower Dir, Bajaur, and Mansehra). The highest occurrence was noted for Hyalomma dromedarii (number = 72, 12.8%), followed by Haemaphysalis sulcata (n = 70, 12.4%), Rhipicephalus turanicus (n = 64, 11.3%), Rhipicephalus microplus (n = 55, 9.7%), Haemaphysalis cornupunctata (n = 49, 8.7%), Hyalomma turanicum (n = 48, 8.5%), Hyalomma isaaci (n = 45, 8.0%), Haemaphysalis montgomeryi (n = 44, 7.8%), Hyalomma anatolicum (n = 42, 7.5%), Haemaphysalis bispinosa (n = 38, 6.7%), and Rhipicephalus haemaphysaloides (n = 37, 6.6%). A subset of 148 ticks were tested, in which eight (5.4%) ticks, including four Hy. turanicum, two Ha. cornupunctata, one Ha. montgomeryi, and one Ha. bispinosa, were found positive for Rickettsia sp. The gltA, ompA, and ompB sequences revealed 100% identity and were phylogenetically clustered with Rickettsia raoultii reported in China, Russia, USA, Turkey, Denmark, Austria, Italy, and France. Additionally, various reports on R. raoultii from Palearctic and Oriental regions were summarized in this study. To the best of our knowledge, this is the first report regarding genetic characterization and phylogenetic analysis of R. raoultii from Pakistan. Further studies to investigate the association between Rickettsia spp. and ticks should be encouraged to apprise effective management of zoonotic consequences.

Spotted Fever Group Rickettsiae in Ticks and Small Mammals from Grassland and Forest Habitats in Central Germany

Rickettsiae of the spotted fever group (SFG) are zoonotic tick-borne pathogens. Small mammals are important hosts for the immature life stages of two of the most common tick species in Europe, Ixodes ricinus and Dermacentor reticulatus. These hosts and vectors can be found in diverse habitats with different vegetation types like grasslands and forests. To investigate the influence of environmental and individual factors on Rickettsia prevalence, this study aimed to analyse the prevalence of SFG rickettsiae in ticks and small mammals in different small-scale habitats in central Germany for the first time. Small mammals of ten species and ticks of two species were collected from grasslands and forests in the Hainich-Dün region, central Germany. After species identification, DNA samples from 1098 ticks and ear snips of 1167 small mammals were screened for Rickettsia DNA by qPCR targeting the gltA gene. Positive samples were retested by conventional PCR targeting the ompB gene and sequencing. Rickettsia DNA was detected in eight out of ten small mammal species. Small mammal hosts from forests (14.0%) were significantly more often infected than those from grasslands (4.4%) (p < 0.001). The highest prevalence was found in the mostly forest-inhabiting genus Apodemus (14.8%) and the lowest in Microtus (6.6%), which inhabits grasslands. The prevalence was higher in D. reticulatus (46.3%) than in the I. ricinus complex (8.6%). Adult ticks were more often infected than nymphs (p = 0.0199). All sequenced rickettsiae in I. ricinus complex ticks were R. helvetica, and the ones in D. reticulatus were R. raoultii. Unlike adults, questing nymphs have had only one blood meal, which explains the higher prevalence in I. ricinus adults. Interestingly, habitat type did influence infection probability in small mammals, but did not in ticks. A possible explanation may be the high prevalence in Apodemus flavicollis and A. sylvaticus which were more abundant in the forest.

Bartonella, Rickettsia, Babesia, and Hepatozoon Species in Fleas (Siphonaptera) Infesting Small Mammals of Slovakia (Central Europe)

Fleas (Siphonaptera) as obligate, blood-feeding ectoparasites are, together with ticks, hosted by small mammals and can transmit causative agents of serious infections. This study aimed to determine and characterize the presence and genetic diversity of Bartonella, Rickettsia, and apicomplexan parasites (Babesia, Hepatozoon) in fleas feeding on small mammals from three different habitat types (suburban, natural, and rural) in Slovakia. The most common pathogen in the examined fleas was Bartonella spp. (33.98%; 95% CI: 30.38-37.58), followed by Rickettsia spp. (19.1%; 95% CI: 16.25-22.24) and apicomplexan parasites (4.36%; 95% CI: 2.81-5.91). Bartonella strains belonging to B. taylorii, B. grahamii, B. elizabethae, Bartonella sp. wbs11, and B. rochalimae clades were identified in Ctenophthalmus agyrtes, C. congener, C. assimilis, C. sciurorum, C. solutus, C. bisoctodentatus, Palaeopsylla similis, Megabothris turbidus, and Nosopsyllus fasciatus within all habitats. The presence of Rickettsia helvetica, R. monacensis, and rickettsiae, belonging to the R. akari and R. felis clusters, and endosymbionts with a 96-100% identity with the Rickettsia endosymbiont of Nosopsyllus laeviceps laeviceps were also revealed in C. agyrtes, C. solutus, C. assimilis, C. congener, M. turbidus, and N. fasciatus. Babesia and Hepatozoon DNA was detected in the fleas from all habitat types. Hepatozoon sp. was detected in C. agyrtes, C. assimilis, and M. turbidus, while Babesia microti was identified from C. agyrtes, C. congener, and P. similis. The present study demonstrated the presence of zoonotic pathogens in fleas, parasitizing the wild-living small mammals of southwestern and central Slovakia and widens our knowledge of the ecology and genomic diversity of Bartonella, Rickettsia, Babesia, and Hepatozoon.

Update on prevalence of Babesia canis and Rickettsia spp. in adult and juvenile Dermacentor reticulatus ticks in the area of Poland (2016-2018)

Ornate dog tick, Dermacentor reticulatus is an important vector of Babesia canis, and Rickettsia spp. and other pathogens of veterinary and public health interest. The current study is the first to investigate the long-term changes in prevalence of these pathogens in expanding tick populations in Central Europe. Molecular techniques (PCR, sequencing) were applied for the detection of pathogen DNA in adult (n = 2497) and juvenile ticks (1096 larvae and 410 nymphs). DNA of Rickettsia spp. was identified in 35% of adults and 12.6% of juvenile ticks. DNA of B. canis was detected in 3% of adult ticks and only in ticks from the Eastern region (regional prevalence 6%). As previously, no B. canis-positive ticks were found in Western Poland, including ticks from Wrocław area (n = 298). DNA of B. canis was identified in 0.33% of juvenile ticks (in 3 pools of larvae and 2 nymphs) from the Eastern region. In the current study we confirmed high occurrence of R. raoultii in adults ticks from all four zones and relatively high prevalence of B. canis in the Eastern population of D. reticulatus, corresponding well with high incidence of canine babesiosis in this area of Poland. Finally, we confirmed R. raoultii and B. canis infection in all life stages of D. reticulatus ticks.

Culture Isolate of Rickettsia felis from a Tick

Although the cat flea, Ctenocephalides felis, has been identified as the primary vector of Rickettsia felis, additional flea, tick, mite, and louse species have also been associated with this bacterium by molecular means; however, the role of these arthropods in the transmission of R. felis has not been clarified. Here, we succeeded in culture isolation of R. felis from a host-seeking castor bean tick, Ixodes ricinus, the most common tick in Slovakia. The bacterial isolation was performed on XTC-2 cells at 28 °C using the shell-vial technique. An evaluation of the growth properties was performed for both the XTC-2 and Vero cell lines. We observed R. felis in the infected host cells microscopically by Gimenez staining and immunofluorescence assay. The R. felis isolate was purified by gradient ultracentrifugation and visualized by electron microscopy. Fragments of the genes gltA, ompA, ompB, htrA, rpoB, sca4, rffE, and rrs were amplified and compared with the corresponding sequences of the type strain URRWXCal2 and other R. felis culture -isolated strains. We did not detect any nucleotide polymorphisms; however, plasmid pRFδ, characteristic of the standard strain, was absent in our isolate. Herein, we describe the first successful isolation and characterization of a tick-derived R. felis strain “Danube”, obtained from an I. ricinus nymph.

Molecular Detection of Zoonotic and Non-Zoonotic Pathogens from Wild Boars and Their Ticks in the Corsican Wetlands

Corsica is the main French island in the Mediterranean Sea and has high levels of human and animal population movement. Among the local animal species, the wild boar is highly prevalent in the Corsican landscape and in the island’s traditions. Wild boars are the most commonly hunted animals on this island, and can be responsible for the transmission and circulation of pathogens and their vectors. In this study, wild boar samples and ticks were collected in 17 municipalities near wetlands on the Corsican coast. A total of 158 hunted wild boars were sampled (523 samples). Of these samples, 113 were ticks: 96.4% were Dermacentor marginatus, and the remainder were Hyalomma marginatum, Hyalomma scupense and Rhipicephalus sanguineus s.l. Of the wild boar samples, only three blood samples were found to be positive for Babesia spp. Of the tick samples, 90 were found to be positive for tick-borne pathogens (rickettsial species). These results confirm the importance of the wild boar as a host for ticks carrying diseases such as rickettsiosis near wetlands and recreational sites. Our findings also show that the wild boar is a potential carrier of babesiosis in Corsica, a pathogen detected for the first time in wild boars on the island.

Ticks and their epidemiological role in Slovakia: from the past till present

In Slovakia, 22 tick species have been found to occur to date. Among them, Ixodes ricinus, Dermacentor reticulatus, D. marginatus and marginally Haemaphysalis concinna, H. inermis and H. punctata have been identified as the species of public health relevance. Ticks in Slovakia were found to harbour and transmit zoonotic and/or potentially zoonotic agents such as tick-borne encephalitis virus (TBEV), spirochaetes of the Borrelia burgdorferi sensu lato (s.l.) complex, the relapsing fever sprirochaete Borrelia miyamotoi, bacteria belonging to the orders Rickettsiales (Rickettsia spp., Anaplasma phagocytophilum, Neoehrlichia mikurensis), Legionellales (Coxiella burnetii), and Thiotrichales (Francisella tularensis), and Babesia spp. parasites (order Piroplasmida). Ixodes ricinus is the principal vector of the largest variety of microorganisms including viruses, bacteria and piroplasms. TBEV, B. burgdorferi s.l., rickettsiae of the spotted fever group, C. burnetii and F. tularensis have been found to cause serious diseases in humans, whereas B. miyamotoi, A. phagocytophilum, N. mikurensis, Babesia microti, and B. venatorum pose lower or potential risk to humans. Distribution of TBEV has a focal character. During the last few decades, new tick-borne encephalitis (TBE) foci and their spread to new areas have been registered and TBE incidence rates have increased. Moreover, Slovakia reports the highest rates of alimentary TBE infections among the European countries. Lyme borreliosis (LB) spirochaetes are spread throughout the distribution range of I. ricinus. Incidence rates of LB have shown a slightly increasing trend since 2010. Only a few sporadic cases of human rickettsiosis, anaplasmosis and babesiosis have been confirmed thus far in Slovakia. The latest large outbreaks of Q fever and tularaemia were recorded in 1993 and 1967, respectively. Since then, a few human cases of Q fever have been reported almost each year. Changes in the epidemiological characteristics and clinical forms of tularaemia have been observed during the last few decades. Global changes and development of modern molecular tools led to the discovery and identification of emerging or new tick-borne microorganisms and symbionts with unknown zoonotic potential. In this review, we provide a historical overview of research on ticks and tick-borne pathogens in Slovakia with the most important milestones and recent findings, and outline future directions in the investigation of ticks as ectoparasites and vectors of zoonotic agents and in the study of tick-borne diseases.

Climate and the seasonal abundance of the tick Dermacentor reticulatus

Dermacentor reticulatus (Ixodida: Ixodidae, Fabricius 1794) is one of the most widely distributed and abundant tick species in central Europe and is a vector for a range of pathogens. Nevertheless, many aspects of its ecology and distribution remain poorly understood. To quantify the seasonal abundance of this species in the U.K. and the environmental factors that determine this, weekly sampling at sites throughout Wales and southern England was undertaken for 12 months. This showed that the activity of adult D. reticulatus peaked February and March and that no individuals were collected between May and mid-October; no questing tick activity was observed when the 5-day average temperature was greater than 15 °C. A single nymph was collected by dragging, confirming speculation over the nidicolous status of larval and nymphal stadia. Laboratory analysis found that D. reticulatus were able survive cold shock and the lower lethal temperature was estimated to be between -18 and -20 °C. Habitat was significantly associated with tick activity, with higher numbers of ticks collected from low lying vegetation in marsh environments than from exposed grassland or woodland. A strong association was observed between activity and saturation deficit suggesting that the seasonal pattern of activity seen in the field, within the sites where it was abundant, is more strongly determined by temperature than humidity. Range expansion within the U.K. should be expected, bringing with it an elevated disease risk for animal and human hosts.

Preliminary Evidence of Rickettsia slovaca and Rickettsia conorii Infection in the Sera of Sheep, Dogs and Deer from an Area of Northern Spain

Limited information is available on the presence of rickettsial infection in animal reservoirs in Spain. Antibodies against Rickettsia slovaca and Rickettsia conorii were therefore sought in the sera of farm, domestic and wild animals (n = 223 samples) in an area of northern Spain. Indirect immunofluorescence assays showed: (A) 17/120 and 16/120 (14.2% and 13.3%) of serum samples from sheep (farm animals) reacted with R. slovaca and R. conorii antigens, respectively; (B) 10/73 and 10/73 (13.7% and 13.7%) of samples from dogs (domestic animals) did the same; (C) as did 22/30 and 20/30 (73.3% and 66.6%) of samples from deer (wild animals) (overall titre range: 1/40 to 1/1280). The prevalence of both types of infection was significantly greater in the wild animals than either the farm or domestic animals. The largest titres were recorded for R. slovaca in all three groups.

Detection of Rickettsia raoultii in Dermacentor reticulatus and Haemaphysalis inermis ticks in Slovakia

Ticks are vector arthropods responsible for the transmission of several pathogenic agents that affect both human and animal health worldwide. In this study our objective was to analyse, using molecular tools, the bacterial community of Dermacentor reticulatus and Haemaphysalis inermis ticks collected in south-eastern Slovakia. Using real-time PCR, we identified the presence of Rickettsia spp. DNA at levels of 14/59 (23.72 %) and 29/173 (16.76 %) in D. reticulatus and H. inermis, respectively. In addition, using standard PCR and sequencing, we identified the presence of Rickettsia raoultii DNA in 13 ticks belonging to the two investigated species. Rickettsia raoultii blast results revealed an average identification percentage of 99.62 %. Following the results of this molecular study there is a possibility that D. reticulatus and H. inermis play a potential role in the transmission of R. raoultii. To prove the possibility of validity of this hypothesis, we suggest performing experimental models in future studies. Our results can serve as preliminary data for future transmission models.

Replication Kinetics of Rickettsia raoultii in Tick Cell Lines

Rickettsia raoultii is one of the causative agents of tick-borne lymphadenopathy in humans. This bacterium was previously isolated and propagated in tick cell lines; however, the growth characteristics have not been investigated. Here, we present the replication kinetics of R. raoultii in cell lines derived from different tick genera (BME/CTVM23, RSE/PILS35, and IDE8). Tick cell cultures were infected in duplicate with cryopreserved R. raoultii prepared from homologous cell lines. By 12–14 days post infection, 100% of the cells were infected, as visualized in Giemsa-stained cytocentrifuge smears. R. raoultii growth curves, determined by rickettsiae-specific gltA qPCR, exhibited lag, exponential, stationary and death phases. Exponential phases of 4–12 days and generation times of 0.9–2.6 days were observed. R. raoultii in BME/CTVM23 and RSE/PILS35 cultures showed, respectively, 39.5- and 37.1-fold increases compared to the inoculum. In contrast, multiplication of R. raoultii in the IDE8 cultures was 110.1-fold greater than the inoculum with a 7-day stationary phase. These findings suggest variation in the growth kinetics of R. raoultii in the different tick cell lines tested, amongst which IDE8 cells could tolerate the highest levels of R. raoultii replication. Further studies of R. raoultii are needed for a better understanding of its persistence within tick populations.

Rickettsiae in red fox (Vulpes vulpes), marbled polecat (Vormela peregusna) and their ticks in northwestern China

BACKGROUND

Previously, twelve Rickettsia species were identified in ticks, fleas, sheep keds (Melophagus ovinus), bats (Pipistrellus pipistrellus) and a tick-bitten patient in the Xinjiang Uygur Autonomous Region (XUAR) in northwestern China. Here we aimed to molecularly detect rickettsial agents in red fox (Vulpes vulpes), marbled polecat (Vormela peregusna) and their ticks.

METHODS

During 2018-2019, 12 red foxes, one marbled polecat and their ticks were sampled in two counties and a city of the XUAR. The heart, liver, spleen, lung and kidney of these 13 carnivores were dissected, followed by DNA extraction. Hard ticks were identified both morphologically and molecularly. All samples were examined for the presence of rickettsiae by amplifying four genetic markers (17-kDa, gltA, ompA, sca1).

RESULTS

A total of 26 adult ticks and 28 nymphs (38 Ixodes canisuga, nine Ixodes kaiseri, six Haemaphysalis erinacei and one Dermacentor marginatus) were collected from red foxes, and four Ha. erinacei ticks were removed from the marbled polecat. Analysis of cytochrome c oxidase subunit I (COI) gene sequences indicated that 2-32 nucleotides differed between I. canisuga, I. kaiseri and Ha. erinacei from northwestern China and Europe. Rickettsia raoultii was detected in three red foxes, Candidatus Rickettsia barbariae in a red fox, Rickettsia sibirica in a red fox and a marbled polecat, and R. raoultii in two tick species (I. canisuga and D. marginatus).

CONCLUSIONS

To the best of our knowledge, I. canisuga and I. kaiseri have not been previously reported from red foxes in China. The DNA of R. sibirica and R. raoultii was detected for the first time in the organs of red foxes, and R. sibirica in the organs of a marbled polecat. This is also the first molecular evidence for the presence of R. raoultii in I. canisuga. Our findings expand the range of tick-borne pathogens in wildlife species and associated ticks in China.

Host-parasite interactions of rodent hosts and ectoparasite communities from different habitats in Germany

Background

Small mammals are important maintenance hosts of ectoparasites as well as reservoir hosts for many arthropod-borne pathogens. In Germany, only a few studies have investigated ectoparasite communities on small mammals in their natural habitats. The aim of this study was to assess the species diversity and parameters influencing the mean intensity and prevalence of macroscopically visible ectoparasites, such as fleas, predatory mites and ticks.

Methods

A total of 779 small mammals and 3383 ticks were available from earlier investigations for the data analysis of the current study from three differently structured study sites. In addition, fleas and predatory mites were collected from the captured rodents and taxonomically identified. Regression analyses were conducted on the group (ticks/mites/fleas) and species levels using hurdle models for the abundance of ectoparasite groups and a negative binomial model for the abundance of species.

Results

Nearly 90% of the small mammals analyzed were infested with ectoparasites, with an average of 7.3 specimens per host. Hosts were infested with up to six species of ectoparasites simultaneously. In total, 12 flea, 11 mite and three tick species were detected. Ticks were more prevalent than fleas or mites, with > 80% of the hosts in urban and forest areas hosting ticks and around 60% of hosts presenting fleas, and only 20–40% of hosts presenting mites. Polyparasitism had a statistically significant influence on the prevalence of the investigated tick, mite and flea species, with odds ratios of > 1.0. Trapping location, season and host characteristics had significant influences on some—but not all—of the investigated species.

Conclusions

The diversity of flea species was unexpectedly high and higher than that reported in comparable studies, which can be explained by the differently structured habitats and regions examined in this study. Polyparasitism was a key influencing factor and had a positive effect on the prevalence and/or abundance of the predominant tick, flea and mite species occurring on small mammals. Season, trapping location, host species and sex of the host species also had an influence on the prevalence and mean intensity of certain, but not all, ectoparasite species.

The Unexpected Holiday Souvenir: The Public Health Risk to UK Travellers from Ticks Acquired Overseas

Overseas travel to regions where ticks are found can increase travellers' exposure to ticks and pathogens that may be unfamiliar to medical professionals in their home countries. Previous studies have detailed non-native tick species removed from recently returned travellers, occasionally leading to travel-associated human cases of exotic tick-borne disease. There are 20 species of tick endemic to the UK, yet UK travellers can be exposed to many other non-native species whilst overseas. Here, we report ticks received by Public Health England's Tick Surveillance Scheme from humans with recent travel history between January 2006 and December 2018. Altogether, 16 tick species were received from people who had recently travelled overseas. Confirmed imports (acquired outside of the UK) were received from people who recently travelled to 22 countries. Possible imports (acquired abroad or within the UK) were received from people who had recently travelled to eight European countries. Species-specific literature reviews highlighted nine of the sixteen tick species are known to vector at least one tick-borne pathogen to humans in the country of acquisition, suggesting travellers exposed to ticks may be at risk of being bitten by a species that is a known vector, with implications for novel tick-borne disease transmission to travellers.

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.

Detection of pathogens in ixodid ticks collected from animals and vegetation in five regions of Ukraine

The distribution and prevalence of zoonotic pathogens infecting ixodid ticks in Western Europe have been extensively examined. However, data on ticks and tick-borne pathogens in Eastern Europe, particularly Ukraine are scarce. The objective of the current study was, therefore, to investigate the prevalence of Anaplasma phagocytophilum, Anaplasmataceae, Rickettsia spp., Babesia spp., Bartonella spp., and Borrelia burgdorferi sensu lato in engorged and questing ixodid ticks collected from five administrative regions (oblasts) of Ukraine, namely Chernivtsi, Khmelnytskyi, Kyiv, Ternopil, and Vinnytsia. The ticks were collected from both wild and domestic animals and from vegetation. Of 524 ixodid ticks collected, 3, 99, and 422 ticks were identified as Ixodes hexagonus, Ixodes ricinus, and Dermacentor reticulatus, respectively. DNA samples individually extracted from 168 questing and 354 engorged adult ticks were subjected to pathogen-specific PCR analyses. The mean prevalence in I. ricinus and D. reticulatus were, respectively: 10 % (10/97) and 3 % (12/422) for A. phagocytophilum; 69 % (67/97) and 52 % (220/422) for members of the Anaplasmataceae family; 25 % (24/97) and 28 % (117/422) for Rickettsia spp.; 3 % (3/97) and 1 % (6/422) for Babesia spp.; and 9 % (9/97) and 5 % (20/422) for Bartonella spp. Overall, between the five cities, there was no significant difference in the prevalence of any of the pathogens for the respective ticks (p > 0.05). The prevalence of B. burgdorferi s. l. in the questing and engorged I. ricinus varied from 0 to 27 % and 14-44%, respectively, with no statistical significance identified between the five cities (p > 0.05). In addition to reporting the updated data for Kyiv and Ternopil, this study is the first to provide the prevalences of the tick-borne pathogens for Chernivtsi, Khmelnytskyi, and Vinnytsia. This investigation is also the first to detect Neoehrlichia mikurensis in ixodid ticks from Ukraine. These new data will be useful for medical and veterinary practitioners as well as public health officials when diagnosing infections and when implementing measures to combat tick-borne diseases in Ukraine.

Epidemiology, Clinical Aspects, Laboratory Diagnosis and Treatment of Rickettsial Diseases in the Mediterranean Area During COVID-19 Pandemic: A Review of the Literature

The purpose of the present review is to give an update regarding the classification, epidemiology, clinical manifestation, diagnoses, and treatment of the Rickettsial diseases present in the Mediterranean area.

We performed a comprehensive search, through electronic databases (Pubmed – MEDLINE) and search engines (Google Scholar), of peer-reviewed publications (articles, reviews, and books).

The availability of new diagnostic tools, including Polymerase Chain Reaction and nucleotide sequencing has significantly modified the classification of intracellular bacteria, including the order Rickettsiales with more and more new Rickettsia species recognized as human pathogens. Furthermore, emerging Rickettsia species have been found in several countries and are often associated with unique clinical pictures that may challenge the physician in the early detection of the diseases.

Rickettsial infections include a wide spectrum of clinical presentations ranging from a benign to a potentially life treating disease that requires prompt recognition and proper management. Recently, due to the spread of SARS-CoV-2 infection, the differential diagnosis with COVID-19 is of crucial importance. The correct understanding of the clinical features, diagnostic tools, and proper treatment can assist clinicians in the management of Rickettsioses in the Mediterranean area.

Collection of immature Dermacentor reticulatus (Fabricius, 1794) ticks from vegetation and detection of Rickettsia raoultii in them

It is commonly assumed that Dermacentor reticulatus immature life stages are nidicolous and therefore cannot be collected from vegetation. However, in June and July of 2018 and 2019, a total of 47 questing D. reticulatus larvae and two nymphs were collected by the flagging method in two different sites close to the city of Leipzig, Germany. To confirm their role in the transmission of tick-borne pathogens, 45 larvae (pooled by 2 in 21 pools and 1 pool with three individuals) and one nymph were tested either by conventional or real-time PCR for the presence of Bartonella spp., Neoehrlichia mikurensis, Rickettsia spp., and Babesia spp. All samples tested negative for Bartonella spp., N. mikurensis, and Babesia spp.; while the minimal infection rate of larvae for Rickettsia spp. was 42%, and the one tested nymph was also positive. Sequencing partial ompB genes revealed the presence of Rickettsia raoultii in larvae and nymph. Further research needs to be done to determine under which circumstances immature D. reticulatus ticks are found outside the burrows of their hosts and can be collected from vegetation.

Ability of Adult Dermacentor reticulatus Ticks to Overwinter in the Temperate Climate Zone

Dermacentor reticulatus ticks, one of the most important vectors and reservoirs of tick-borne diseases in Europe, are widespread in the temperate climate zone and in some localities in the subtropical climate zone of the western Palaearctic region. These ticks occur in a large area characterised by a varied climate type, vegetation, and availability of potential hosts. Hence, they exhibit high ecological plasticity and adaptability to periodically adverse conditions. The aim of the present study was to investigate the ability of D. reticulatus adults to overwinter in the natural habitat. Specimens marked with a permanent oil marker on the festoons were placed in their natural habitats for the winter. Concurrently, tick survival in laboratory conditions at a temperature of 5 °C and 18 °C was assessed as a control. The groups were compared with each other by determination of the weight of fat bodies. In the field conditions, 67.9% females and 60.0% males survived the winter. There was no significant difference in the survival of ticks in the laboratory. A significantly lower fat body weight was found in the group of ticks overwintering in the field conditions and exhibiting questing activity between spring and late autumn during the following year. On the population scale, adult D. reticulatus ticks are able to survive the winter in temperate climate conditions at a level ensuring a further increase in their population size. In adverse weather conditions, ticks enter diapause, thus maximally reducing the utilisation of the content of their fat bodies. This facilitates long-term survival in the environment.

Molecular investigation of Rickettsia spp. and Francisella tularensis in ticks from three provinces of Turkey

Ticks are obligate hematophagous ectoparasites as well as mechanical and biological vectors of a wide variety of microbial pathogens. To date, 19 tick-borne diseases have been reported from Turkey. In this study, ticks collected from Aydın, İzmir and Şanlıurfa provinces of Turkey were identified using morphological and molecular methods. After the presence of bacterial DNA was checked, Rickettsia spp. and Francisella tularensis were investigated in bacterial DNA-positive tick specimens by PCR. Furthermore, amplicons belonging to tick specimens and positive bacterial samples were sequenced and processed for BLAST, alignment and phylogenetic analysis. As a result, seven tick species were identified: Rhipicephalus sanguineus, Rh. bursa, Rh. turanicus, Hyalomma marginatum, Hy. aegyptium, Hy. anatolicum and Haemaphysalis erinacei. Fifty-five tick specimens tested positive for bacterial DNA and among them, rickettsial DNA was found in five ticks (infection rate = 9.1%) belonging to Hy. marginatum, Hy. aegyptium, Rh. bursa and Rh. turanicus. Of the five Rickettsia-positive ticks, three contained Rickettsia aeschlimannii, one Ri. massiliae and one an unidentified Rickettsia sp. No Francisella tularensis DNA was detected. Sequence analysis of the ompB gene indicated two novel single nucleotide polymorphisms (SNP) in two different Ri. aeschlimannii strains and two novel SNPs as well as a novel insertion (GACGGT) were found in Rickettsia sp. This study indicated the presence of polymorphic Rickettsia species in ticks from Turkey.

Circulation of Rickettsia species and rickettsial endosymbionts among small mammals and their ectoparasites in Eastern Slovakia

Bacteria belonging to the genus Rickettsia are known as causative agents of vector-borne zoonotic diseases, such as spotted fevers, epidemic typhus and endemic typhus. Different species of ticks, mites and fleas could act as reservoirs and arthropod vectors of different pathogenic Rickettsia species. The aim of this work was to establish active surveillance of Rickettsia spp. in mites, ticks and fleas collected from small mammals (rodents and shrews) in Eastern Slovakia. A total of 964 animal ear biopsies, 871 mites, 667 ticks and 743 fleas were collected from small mammals in the Košice region, Eastern Slovakia. All specimens were identified using specialized taxonomic keys, and were conserved in ethanol until DNA extraction was performed. After DNA extraction, identification of Rickettsia species was performed by PCR-based methods. The total prevalence of rickettsiae from ear biopsies was 4.6% (95% CI, 3.2-5.9), in tested mites 9.3% (95% CI, 7.4-11.2), 17.2% (95% CI, 14.3-20.1) in I. ricinus ticks and 3.5% (95% CI, 2.2-4.8) in fleas. Sequence analysis of the partial gltA gene and Rickettsia helvetica-, Rickettsia slovaca-, Rickettsia raoultii- species specific real-time PCR tests revealed the presence of R. helvetica, R. slovaca, unidentified Rickettsia and rickettsial endosymbionts. These pathogenic and symbiotic species were confirmed in the following ectoparasite species-Laelaps jettmari, Haemogamasus nidi, Laelaps agilis and Eulaelaps stabularis mites, Ixodes ricinus ticks, Ctenophthalmus solutus, C. assimilis and Megabothris turbidus fleas infesting host-Apodemus agrarius, A. flavicollis, Microtus arvalis and Myodes glareolus small mammals. These results confirm the circulation of R. helvetica, R. slovaca, unidentified Rickettsia and rickettsial endosymbionts in mites, ticks and fleas collected on small mammals in the Košice region, Eastern Slovakia.

Detection of Rickettsia spp. in Fleas Collected from Small Mammals in Slovakia, Central Europe

This survey is aimed at investigation of species composition of fleas removed from small terrestrial mammals captured in rural, suburban, and urban types of habitat and molecular screening of the presence and diversity of Rickettsia species in collected ectoparasites. In total, 279 fleas (Siphonaptera) belonging to 9 species of 2 families, Ceratophyllidae and Hystrichopsyllidae, were collected from 115 (46%) out of 250 trapped small mammals of eight species (Apodemus agrarius, Apodemus flavicollis, Apodemus uralensis, Myodes glareolus, Microtus arvalis, Microtus subterraneus, Crocidura leucodon, and Sorex minutus). Rickettsia spp. were found in 2.5% (7/279) of tested fleas, namely in Ctenophthalmus agyrtes, Ctenophthalmus solutus, Ctenophthalmus uncinatus, Megabothris turbidus, and Amalareus penicilliger. Rickettsia felis, Rickettsia helvetica, and unidentified Rickettsia species were detected in fleas infesting small mammals in Eastern Slovakia. The results of the study suggest that some species of rickettsiae have a different range of arthropod vectors.

Density of Dermacentor reticulatus Ticks in Eastern Poland

Dermacentor reticulatus, the ornate cow tick, is second only to Ixodes ricinus as the most important reservoir and vector of infectious diseases in Europe. In recent years, the distribution of D. reticulatus ticks has expanded into new territories, including increased population densities in areas of their previous occurrence. Our investigations around this consisted of two stages. In the first stage, we monitored the seasonal activity of D. reticulatus ticks in Polesie National Park in 2014-2019. The second stage, which was carried out in 2019 at the peak of the spring (March) and autumn (October) activity of this species, included assessment of the density of D. reticulatus ticks in the entire province. To this end, the study area was divided into 101 equal plots that were surveyed for ticks. The seasonal activity of D. reticulatus in Polesie National Park showed peaks of activity in autumn in 2014-2018 and in spring in 2019. A total of 19,559 adult D. reticulatus specimens were collected, with a mean of 96.8 specimens/100 m² in Lublin Province. The area of Lublin Province is characterized by a high density of the ornate cow tick. An increase in the surface area of meadows and fallow land has contributed to a rise in the number of local populations of D. reticulatus ticks.

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.

Optimized fixation of actin filaments for improved indirect immunofluorescence staining of rickettsiae

Objective

The objective was to investigate fixative solutions: 3.7% formaldehyde, 4% paraformaldehyde, 4% paraformaldehyde in the cytoskeletal buffer and 4% paraformaldehyde in PHEM buffer (containing PIPES, HEPES, EGTA and MgCl₂), applicable for immunofluorescence assay.

Results

Herein we optimized this serological technique, testing four fixative solutions, for the sensitive detection of rickettsial antigens, and preservation of intracellular structures of the host cells, particularly filamentous actin. Rickettsial antigens were presented equally well both with formaldehyde and all paraformaldehyde-based fixations, but only protocol with 4% paraformaldehyde in PHEM buffer allowed accurate imaging of actin filaments, and simultaneously allows monitoring of rickettsiae using actin-based motility during infection inside the host cells.

Prevalence and molecular characterization of Rickettsia spp. in questing ticks from north-western Spain

Tick-borne rickettsioses, most of them belonging to the spotted fever group (SFG), have been recognized as important emerging vector-borne zoonotic diseases. In order to determine the presence of Rickettsia spp. in questing ticks from north-western Spain, 1056 Ixodes ricinus, 19 Dermacentor marginatus, 17 Dermacentor reticulatus and one Ixodes acuminatus were processed. Rickettsia DNA was detected by PCR targeting rOmpA and rOmpB genes. A total of 219 (20.7%) I. ricinus, 19 (100%) D. marginatus and four D. reticulatus (23.5%) were positive. The prevalence was significantly higher in I. ricinus from coastal areas and in winter. Five species were identified: Rickettsia felis, Rickettsia monacensis, Rickettsia raoultii, Rickettsia slovaca and "Candidatus Rickettsia rioja". Our results reveal a significant presence of some pathogenic Rickettsia species in questing tick populations from this area which involves a noticeable risk of rickettsiosis. As R. raoultii, R. slovaca and "Ca. R. rioja" DNA were identified in I. ricinus, considered an unusual vector for these Rickettsia species, further studies are needed to unravel the role of that tick species in the maintenance and transmission of these three Rickettsia species in north-western Spain.

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.

Comparative proteomics of the vector Dermacentor reticulatus revealed differentially regulated proteins associated with pathogen transmission in response to laboratory infection with Rickettsia slovaca

BACKGROUND

Tick-borne rickettsial diseases are caused by pathogens acquired from hard ticks. In particular, Rickettsia slovaca, a zoonotic infectious bacterium causing tick-borne lymphadenopathy (TIBOLA), is transmitted by the vectors Dermacentor spp. that can be found all over Europe. Although recent studies point out the extreme complexity of bacteria-induced effects in these blood-feeding vectors, the knowledge of individual molecules involved in the preservation and transmission of the pathogen is still limited. System biology tools, including proteomics, may contribute greatly to the understanding of pathogen-tick-host interactions.

METHODS

Herein, we performed a comparative proteomics study of the tick vector Dermacentor reticulatus that was experimentally infected with the endosymbiotic bacterium R. slovaca. Rickettsia-free ticks, collected in the southern region of Slovakia, were infected with the bacterium by a capillary tube-feeding system, and the dynamics of infection was assessed by quantitative PCR method after 5, 10, 15 and 27 days.

RESULTS

At the stage of controlled proliferation (at 27 dpi), 33 (from 481 profiled) differentially abundant protein spots were detected on a two-dimensional gel. From the aforementioned protein spots, 21 were successfully identified by tandem mass spectrometry.

CONCLUSIONS

Although a few discovered proteins were described as having structural or housekeeping functions, the vast majority of the affected proteins were suggested to be essential for tick attachment and feeding on the host, host immune system evasion and defensive response modulation to ensure successful pathogen transmission.

Dermacentor reticulatus in Berlin/Brandenburg (Germany): Activity patterns and associated pathogens

Dermacentor reticulatus is one of the most important European tick species. However, its spatial distribution, seasonality and regional vector role are not well known. This study aimed to gather information about abundance patterns of questing ticks and associated pathogens in unfed female adult D. reticulatus in the Berlin/Brandenburg area. Using the flagging method, questing ticks were collected at four sites in 2010-2012 and 2000 D. reticulatus were analysed regarding infection with Rickettsia, Babesia, Borrelia and Anaplasmataceae by conventional or real-time PCR. Dermacentor reticulatus showed a bimodal activity pattern: highest numbers of adult ticks were recorded between March and end of May (mean 50 ticks/h) and from mid-August until end of November (mean 102 ticks/h). During summer, almost complete inactivity was observed (mean 0.4 ticks/h). Sporadic samplings from December to February revealed tick activity also during winter (mean 47 ticks/h), which was characterised by large fluctuations. Using negative binomial regression analysis, significant influences of the variables sampling site, season and temperature on the abundance of questing D. reticulatus were determined. The parameters relative humidity and year were not of significant importance. PCR analyses showed an average prevalence of 64% for Rickettsia sp. Large differences in pathogen frequencies were observed between sampling sites (31.4-78.3%). Regression analysis demonstrated a significant influence of the sampling site but not of season and year. Examinations regarding other pathogen groups indicated prevalences of 0.25% (Borrelia sp.) and 0.05% (Anaplasmataceae) but absence of Babesia sp. Sequencing of positive samples revealed infections with Rickettsia raoultii, Borrelia miyamotoi, Borrelia afzelii and Anaplasma phagocytophilum. The study shows stable populations of D. reticulatus in Berlin/Brandenburg. People should be aware of ticks throughout the year since Ixodes ricinus is co-endemic and active in spring, summer and autumn while adult D. reticulatus are active throughout the year and even in winter during periods of frost as long as it is warming up during the day. Prevalence of R. raoultii in the present study is among the highest described for D. reticulatus. Borrelia miyamotoi was detected for the first time in D. reticulatus, illustrating the importance of screening studies to evaluate the pathogen structure in D. reticulatus populations.

Low-cost light-induced therapy to treat rickettsial infection

Antimicrobial photodynamic therapy uses a nontoxic photosensitizer with the assistance of harmless visible light to activate the photosensitizer. Consequently, the excited state of the photosensitizer interacts with molecular oxygen to produce reactive oxygen species, which have the antimicrobial effect. In this study, we evaluated the effect of photodynamic therapy on Vero cells infected with rickettsia using methylene blue as a photosensitizer along with red light. A significant reduction (by 96%) in the number of viable Rickettsia slovaca was determined by quantitative RT-PCR 48 h after the treatment with methylene blue followed by 30 min of red light excitation. A statistically significant reduction of R. slovaca was also recorded with pretreatment (by 99%). To the best of our knowledge, this result is the first one in the literature to confirm the effectiveness of photodynamic therapy for the elimination of R. slovaca and to suggest this technique as a good supportive treatment for rickettsial infections.

Hard tick (Acari: Ixodidae) species of livestock and their seasonal activity in Boyer-Ahmad and Dena cities of Kohgiluyeh and Boyer-Ahmad Province, Southwest of Iran

Aim:

The present study was carried out to identify the Ixodidae ticks fauna of livestock and their seasonal activity in the cities of Boyer-Ahmad and Dena of Kohgiluyeh Province, south-west of Iran.

Materials and Methods:

Hard ticks from sheep, goats, and cattle were collected manually, stored in 70% ethanol, and identified using morphological characters.

Results:

During the study, a total of 1273 hard ticks from four genera, including Rhipicephalus, Hyalomma, Dermacentor, and Haemaphysalis, were collected. Rhipicephalus sanguineus (s.l.) had the highest frequencies in both cities with 62.08 and 62.88% of collected specimens, followed by Hyalomma scupense with 14.36 and 13.54% in Boyer-Ahmad and Dena, respectively. Furthermore, Hyalomma marginatum with only one sample or 0.12% of collected ticks showed the lowest frequencies in the studied areas. Dermacentor marginatus with three samples or 0.37% was recorded only in Boyer-Ahmad, and Haemaphysalis sulcata with two samples or 0.43% was recorded only in Dena. In both cities, sheep were the most infested ruminant, and the ears in sheep and goats were the most affected areas. The highest activity was observed in spring, and the lowest activity was observed in winter and autumn.

Conclusion:

The results of the present study showed that Hyalomma and Rhipicephalus genera were the most widespread genera in the study areas. Regarding the importance of genera, such as Rhipicephalus, Hyalomma, and Haemaphysalis, in transmitting disease agents and the location of Kohgiloyeh and Boyer-Ahmad Province in the routes of migrant birds, further studies are required to elucidate their exact roles in human and livestock health in these areas.

Transmission of Rickettsia raoultii and Rickettsia massiliae DNA by Dermacentor reticulatus and Rhipicephalus sanguineus (s.l.) ticks during artificial feeding

Background

Tick-borne rickettsial pathogens are emerging worldwide and pose an increased health risk to both humans and animals. A plethora of rickettsial species has been identified in ticks recovered from human and animal patients. However, the detection of rickettsial DNA in ticks does not necessarily mean that these ticks can act as vectors for these pathogens. Here, we used artificial feeding of ticks to confirm transmission of Rickettsia massiliae and Rickettsia raoultii by Rhipicephalus sanguineus (sensu lato) and Dermacentor reticulatus ticks, respectively. The speed of transmission was also determined.

Methods

An artificial feeding system based on silicone membranes were used to feed adult R. sanguineus (s.l.) and D. reticulatus ticks. Blood samples from in vitro feeding units were analysed for the presence of rickettsial DNA using PCR and reverse line blot hybridisation.

Results

The attachment rate of R. sanguineus (s.l.) ticks were 40.4% at 8 h post-application, increasing to 70.2% at 72 h. Rickettsia massiliae was detected in blood samples collected 8 h after the R. sanguineus (s.l.) ticks were placed into the in vitro feeding units. D. reticulatus ticks were pre-fed on sheep and subsequently transferred to the in vitro feeding system. The attachment rate was 29.1 % at 24 h post-application, increasing to 43.6 % at 96 h. Rickettsia raoultii was detected in blood collected 24 h after D. reticulatus was placed into the feeding units.

Conclusions

Rhipicephalus sanguineus (s.l.) and D. reticulatus ticks are vectors of R. massiliae and R. raoultii, respectively. The transmission of R. massiliae as early as 8 h after tick attachment emphasises the importance of removing ticks as soon as possible to minimise transmission. This study highlights the relevance of in vitro feeding systems to provide insight into the vectorial capacity of ticks and the dynamics of tick-borne pathogen transmission.

Diversity of Coxiella-like and Francisella-like endosymbionts, and Rickettsia spp., Coxiella burnetii as pathogens in the tick populations of Slovakia, Central Europe

Ticks are important vectors of pathogens affecting humans and animals worldwide. They do not only carry pathogens but diverse commensal and symbiotic microorganisms are also present in ticks. A molecular screening for tick-borne pathogens and endosymbionts was carried out in Ixodes ricinus, Dermacentor reticulatus and Haemaphysalis inermis questing ticks collected in Slovakia. The presence of Rickettsia spp., Coxiella burnetii, Coxiella-like and Francisella-like microorganisms was evaluated by PCR in 605 individuals and by randomly sequencing 66 samples. Four species of rickettsiae (R. raoultii, R. slovaca, R. helvetica and R. monacensis) were identified and reported with an overall prevalence range between 0.4 and 50.3% (±8.0) depending on tick species, sex and locality. Partial sequencing of the gltA gene of 5 chosen samples in H. inermis showed 99% identity with Candidatus Rickettsia hungarica. The total prevalence of C. burnetii in ticks was 2.2 ± 1.7%; bacteria were confirmed in I. ricinus and D. reticulatus ticks. The sequences from 2 D. reticulatus males and 1 I. ricinus female ticks were compared to GenBank submissions and a 99.8% match was obtained with the pathogenic C. burnetii. Coxiella-like endosymbionts were registered in all three species of ticks from all studied sites with an average prevalence of 32.7 ± 3.7%. A phylogenetic analysis of this Coxiella sp. showed that it does not group with the pathogenic C. burnetii. The prevalence of Francisella-like microorganisms in questing ticks was 47.9 ± 3.9%, however H. inermis (n = 108) were not infested. Obtained sequences were 98% identical with previously identified Francisella-like endosymbionts in D. reticulatus and I. ricinus. Coxiella-like and Francisella-like microorganisms were identified for the first time in Slovakia, they might be considered as a non-pathogenic endosymbiont of I. ricinus, D. reticulatus and H. inermis, and future investigations could aim to assess their role in these ticks. However, this work provided further data and broadened our knowledge on bacterial pathogens and endosymbionts present in ticks in Slovakia to help understanding co-infestations, combined treatments and public health issues linked to tick bites.

Molecular survey of neglected bacterial pathogens reveals an abundant diversity of species and genotypes in ticks collected from animal hosts across Romania

Background

Ticks are transmitting a wide range of bacterial pathogens that cause substantial morbidity and mortality in domestic animals. The full pathogen burden transmitted by tick vectors is incompletely studied in many geographical areas, and extensive studies are required to fully understand the diversity and distribution of pathogens transmitted by ticks.

Results

We sampled 824 ticks of 11 species collected in 19 counties in Romania. Ticks were collected mainly from dogs, but also from other domestic and wild animals, and were subjected to molecular screening for pathogens. Rickettsia spp. was the most commonly detected pathogen, occurring in 10.6% (87/824) of ticks. Several species were detected: Rickettsia helvetica, R. raoultii, R. massiliae, R. monacensis, R. slovaca and R. aeschlimannii. A single occurrence of the zoonotic bacterium Bartonella vinsonii berkhoffii was detected in a tick collected from a dog. Anaplasma phagocytophilum occurred in four samples, and sequences similar to Anaplasma marginale/ovis were abundant in ticks from ruminants. In addition, molecular screening showed that ticks from dogs were carrying an Ehrlichia species identical to the HF strain as well as the enigmatic zoonotic pathogen “Candidatus Neoehrlichia mikurensis”. An organism similar to E. chaffeensis or E. muris was detected in an Ixodes ricinus collected from a fox.

Conclusions

We describe an abundant diversity of bacterial tick-borne pathogens in ticks collected from animal hosts in Romania, both on the level of species and genotypes/strains within these species. Several findings were novel for Romania, including Bartonella vinsonii subsp. berkhoffii that causes bacteremia and endocarditis in dogs. “Candidatus Neoehrlichia mikurensis” was detected in a tick collected from a dog. Previously, a single case of infection in a dog was diagnosed in Germany. The results warrant further studies on the consequences of tick-borne pathogens in domestic animals in Romania.

Electronic supplementary material

The online version of this article (10.1186/s13071-018-2756-1) contains supplementary material, which is available to authorized users.

High prevalence of Rickettsia helvetica in wild small mammal populations in Germany

Since the beginning of the 21st century, spotted fever rickettsioses are known as emerging diseases worldwide. Rickettsiae are obligately intracellular bacteria transmitted by arthropod vectors. The ecology of Rickettsia species has not been investigated in detail, but small mammals are considered to play a role as reservoirs. Aim of this study was to monitor rickettsiae in wild small mammals over a period of five years in four federal states of Germany. Initial screening of ear pinna tissues of 3939 animals by Pan-Rick real-time PCR targeting the citrate synthase (gltA) gene revealed 296 rodents of seven species and 19 shrews of two species positive for rickettsial DNA. Outer membrane protein gene (ompB, ompAIV) PCRs based typing resulted in the identification of three species: Rickettsia helvetica (90.9%) was found as the dominantly occurring species in the four investigated federal states, but Rickettsia felis (7.8%) and Rickettsia raoultii (1.3%) were also detected. The prevalence of Rickettsia spp. in rodents of the genus Apodemus was found to be higher (approximately 14%) than in all other rodent and shrew species at all investigated sites. General linear mixed model analyses indicated that heavier (older) individuals of yellow-necked mice and male common voles seem to contain more often rickettsial DNA than younger ones. Furthermore, rodents generally collected in forests in summer and autumn more often carried rickettsial DNA. In conclusion, this study indicated a high prevalence of R. helvetica in small mammal populations and suggests an age-dependent increase of the DNA prevalence in some of the species and in animals originating from forest habitats. The finding of R. helvetica and R. felis DNA in multiple small mammal species may indicate frequent trans-species transmission by feeding of vectors on different species. Further investigations should target the reason for the discrepancy between the high rickettsial DNA prevalence in rodents and the so far almost absence of clinical apparent human infections.

Prevalence of different Rickettsia spp. in Ixodes ricinus and Dermacentor reticulatus ticks (Acari: Ixodidae) in north-eastern Poland

In two surveys conducted in April and May 2013, a total of 1148 unfed ticks belonging to two species, Ixodes ricinus and Dermacentor reticulatus, were collected by flagging lower vegetation in 15 different localities throughout the Białowieża Primeval Forest (Podlaskie voivodship; north-eastern Poland) and in its buffer zone. In order to establish their infection rate with Rickettsia spp. individual adult ticks and pooled nymphs were tested by real-time PCR targeting the gltA gene. For the further identification of rickettsial species, positive samples were subjected for nested and semi-nested PCR targeting ompA and 16S rRNA genes, respectively, followed by sequencing analysis. Rickettsial DNA was detected in at least 279 ticks (minimum infection rate [MIR], 23.9%), including 52 nymphal and adult I. ricinus (MIR 8.6%) and 222 adult D. reticulatus (41%). Three species of SFG rickettsiae were identified: Rickettsia helvetica and 'Candidatus R. mendelii' in I. ricinus and R. raoultii in D. reticulatus and I. ricinus. Moreover, unidentified Rickettsia spp. which showed 99.4% identity, among others, with the uncultured Rickettsia sp. isolated from Cicadella viridis leafhopper, Rickettsia endosymbiont of Lasioglossum semilucens bee and R. bellii, were detected in I. ricinus, while Rickettsia sp. 98.3-98.4% homologous to Rickettsia secondary endosymbionts of Curculio spp. weevils was found in D. reticulatus. These results confirm the diversity of rickettsiae occurring in Poland. Further studies are needed to expand the knowledge on the species spectrum, prevalence and epidemiology of SFG rickettsiae in the country.

Spread of Dermacentor reticulatus is associated with the loss of forest area

Changes in tick distribution and abundance are among the main drivers of the (re)emergence of transmitted pathogens. We aimed to uncover the reasons of the reported spread of Dermacentor reticulatus in Poland using a variety of proxies of environmental features, ground-measured temperature and remotely-sensed data of temperature and vegetation. Ground-measured temperature was recorded in 2013-2014, in sites where D. reticulatus presence (n = 16) or absence (n = 16) was confirmed. We specifically aimed to test whether changes in phenology of vegetation and the length of the growing season were correlated with field-derived data regarding the presence/absence of D. reticulatus. We also used categorical descriptions of the habitat to capture the vegetation patterns that might delineate the distribution of the tick. We demonstrated that temperature, phenology of vegetation and length of growing season have no correlation with the occurrence of D. reticulatus in Poland. There is, however, a clear association between the trends of the loss of forests and the presence of the tick. This parameter was two times higher at sites colonized by D. reticulatus in comparison to the sites where the population of the tick is not yet established. A spatial analysis demonstrated that the preferred territories for D. reticulatus are those of a highly fragmented landscape within a large patch of homogeneous vegetation, in the vicinity of permanent water courses or reservoirs.

Multi-omics Analysis Sheds Light on the Evolution and the Intracellular Lifestyle Strategies of Spotted Fever Group Rickettsia spp

Arthropod-borne Rickettsia species are obligate intracellular bacteria which are pathogenic for humans. Within this genus, Rickettsia slovaca and Rickettsia conorii cause frequent and potentially severe infections, whereas Rickettsia raoultii and Rickettsia massiliae cause rare and milder infections. All four species belong to spotted fever group (SFG) rickettsiae. However, R. slovaca and R. raoultii cause scalp eschar and neck lymphadenopathy (SENLAT) and are mainly associated with Dermacentor ticks, whereas the other two species cause Mediterranean spotted fever (MSF) and are mainly transmitted by Rhipicephalus ticks. To identify the potential genes and protein profiles and to understand the evolutionary processes that could, comprehensively, relate to the differences in virulence and pathogenicity observed between these four species, we compared their genomes and proteomes. The virulent and milder agents displayed divergent phylogenomic evolution in two major clades, whereas either SENLAT or MSF disease suggests a discrete convergent evolution of one virulent and one milder agent, despite their distant genetic relatedness. Moreover, the two virulent species underwent strong reductive genomic evolution and protein structural variations, as well as a probable loss of plasmid(s), compared to the two milder species. However, an abundance of mobilome genes was observed only in the less pathogenic species. After infecting Xenopus laevis cells, the virulent agents displayed less up-regulated than down-regulated proteins, as well as less number of identified core proteins. Furthermore, their similar and distinct protein profiles did not contain some genes (e.g., ompA/B and rickA) known to be related to rickettsial adhesion, motility and/or virulence, but may include other putative virulence-, antivirulence-, and/or disease-related proteins. The identified evolutionary forces herein may have a strong impact on intracellular expressions and strategies in these rickettsiae, and that may contribute to the emergence of distinct virulence and diseases in humans. Thus, the current multi-omics data provide new insights into the evolution and fitness of SFG virulence and pathogenicity, and intracellular pathogenic bacteria.

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.

Molecular evidence of Rickettsia spp. in ixodid ticks and rodents in suburban, natural and rural habitats in Slovakia

BACKGROUND

Natural foci of tick-borne spotted fever group (SFG) rickettsiae of public health concern have been found in Slovakia, but the role of rodents in their circulation is unclear. Ticks (Ixodes ricinus, Ixodes trianguliceps, Dermacentor marginatus, Dermacentor reticulatus, Haemaphysalis concinna and Haemaphysalis inermis) and tissues of rodents (Apodemus flavicollis, Apodemus sylvaticus, Myodes glareolus, Microtus arvalis, Microtus subterraneus and Micromys minutus) were examined for the presence of SFG rickettsiae and Coxiella burnetii by molecular methods. Suburban, natural and rural habitats were monitored to acquire information on the role of ticks and rodents in the agents' maintenance in various habitat types of Slovakia.

RESULTS

The overall prevalence of rickettsial infection in questing I. ricinus and D. marginatus was 6.6% and 21.4%, respectively. Rickettsia helvetica, R. monacensis and non-identified rickettsial species were detected in I. ricinus, whereas R. slovaca and R. raoultii were identified in D. marginatus. Rickettsia spp.-infected I. ricinus occurred during the whole tick questing period. Rickettsia helvetica dominated (80.5%) followed by R. monacensis (6.5%). The species were present in all studied habitats. Rickettsia slovaca (66.7%) and R. raoultii (33.3%) were identified in D. marginatus from the rural habitat. Apodemus flavicollis was the most infested rodent species with I. ricinus, but My. glareolus carried the highest proportion of Rickettsia-positive I. ricinus larvae. Only 0.5% of rodents (A. flavicollis) and 5.2% of engorged I. ricinus removed from My. glareolus, A. flavicollis and M. arvalis were R. helvetica- and R. monacensis-positive. Coxiella burnetii was not detected in any of the tested samples. We hypothesize that rodents could play a role as carriers of infected ticks and contribute to the maintenance of rickettsial pathogens in natural foci.

CONCLUSIONS

Long-term presence of SFG Rickettsia spp. was confirmed in questing ticks from different habitat types of Slovakia. The results suggest a human risk for infection with the pathogenic R. helvetica, R. monacensis, R. slovaca and R. raoultii.

The enzootic life-cycle of Borrelia burgdorferi (sensu lato) and tick-borne rickettsiae: an epidemiological study on wild-living small mammals and their ticks from Saxony, Germany

BACKGROUND

Borrelia burgdorferi (sensu lato) and rickettsiae of the spotted fever group are zoonotic tick-borne pathogens. While small mammals are confirmed reservoirs for certain Borrelia spp., little is known about the reservoirs for tick-borne rickettsiae. Between 2012 and 2014, ticks were collected from the vegetation and small mammals which were trapped in Saxony, Germany. DNA extracted from ticks and the small mammals' skin was analyzed for the presence of Rickettsia spp. and B. burgdorferi (s.l.) by qPCR targeting the gltA and p41 genes, respectively. Partial sequencing of the rickettsial ompB gene and an MLST of B. burgdorferi (s.l.) were conducted for species determination.

RESULTS

In total, 673 small mammals belonging to eight species (Apodemus agrarius, n = 7; A. flavicollis, n = 214; Microtus arvalis, n = 8; Microtus agrestis, n = 1; Mustela nivalis, n = 2; Myodes glareolus, n = 435; Sorex araneus, n = 5; and Talpa europaea, n = 1) were collected and examined. In total, 916 questing ticks belonging to three species (Ixodes ricinus, n = 741; Dermacentor reticulatus, n = 174; and I. trianguliceps, n = 1) were collected. Of these, 474 ticks were further investigated. The prevalence for Rickettsia spp. and B. burgdorferi (s.l.) in the investigated small mammals was 25.3 and 31.2%, respectively. The chance of encountering Rickettsia spp. in M. glareolus was seven times higher for specimens infested with D. reticulatus than for those which were free of D. reticulatus (OR: 7.0; 95% CI: 3.3-14.7; P < 0.001). In total, 11.4% of questing I. ricinus and 70.5% of D. reticulatus were positive for Rickettsia spp. DNA of B. burgdorferi (s.l.) was detected only in I. ricinus (5.5%). Sequence analysis revealed 9 R. helvetica, 5 R. raoultii, and 1 R. felis obtained from 15 small mammal samples.

CONCLUSION

Small mammals may serve as reservoirs for Rickettsia spp. and B. burgdorferi (s.l.). While the prevalence for Rickettsia spp. in M. glareolus is most likely depending on the abundance of attached D. reticulatus, the prevalence for B. burgdorferi (s.l.) in small mammals is independent of tick abundance. Dermacentor reticulatus may be the main vector of certain Rickettsia spp. but not for Borrelia spp.

First report of Rickettsia raoultii and R. slovaca in Melophagus ovinus, the sheep ked

BACKGROUND

Melophagus ovinus (Diptera: Hippoboscidae), a hematophagous ectoparasite, is mainly found in Europe, Northwestern Africa, and Asia. This wingless fly infests sheep, rabbits, and red foxes, and causes inflammation, wool loss and skin damage. Furthermore, this parasite has been shown to transmit diseases, and plays a role as a vector. Herein, we investigated the presence of various Rickettsia species in M. ovinus.

METHODS

In this study, a total of 95 sheep keds were collected in Kuqa County and Alaer City southern region of Xinjiang Uygur Autonomous Region, northwestern China. First, collected sheep keds were identified on the species level using morphological keys and molecular methods based on a fragment of the 18S ribosomal DNA gene (18S rDNA). Thereafter, to assess the presence of rickettsial DNA in sheep keds, the DNA of individual samples was screened by PCR based on six Rickettsia-specific gene fragments originating from six genes: the 17-kilodalton antigen gene (17-kDa), 16S rRNA gene (rrs), surface cell antigen 4 gene (sca4), citrate synthase gene (gltA), and outer membrane protein A and B genes (ompA and ompB). The amplified products were confirmed by sequencing and BLAST analysis ( https://blast.ncbi.nlm.nih.gov/Blast.cgi?PROGRAM=blastn&PAGE_TYPE=BlastSearch&LINK_LOC=blasthome ).

RESULTS

According to its morphology and results of molecular analysis, the species was identified as Melophagus ovinus, with 100% identity to M. ovinus from St. Kilda, Australia (FN666411). DNA of Rickettsia spp. were found in 12 M. ovinus samples (12.63%, 12/95). Rickettsia raoultii and R. slovaca were confirmed based on phylogenetic analysis, although the genetic markers of these two rickettsial agents amplified in this study showed molecular diversity.

CONCLUSIONS

This is the first report of R. raoultii and R. slovaca DNA in M. ovinus. Rickettsia slovaca was found for the first time around the Taklimakan Desert located in China. This finding extends the geographical range of spotted fever group rickettsiae.