Borrelia burgdorferi sensu lato and spotted fever group rickettsiae in small rodents and attached ticks in the Northern Apennines, Italy

A systematic review and meta-analysis of the prevalence of tick-borne SFGR in China from 2000 to 2022

BACKGROUND

Ticks carry and transmit a wide range of pathogens (bacteria, viruses, and protozoa) that pose significant threats to human and animal health worldwide. Only few meta-analyses have been conducted on the distribution of ticks and tick-borne spotted fever group rickettsia (SFGR). Therefore, this study aims to examine the tick species and SFGR positivity in China in order to provide support for further research and improvements in the prevention and control of tick-borne diseases.

METHODOLOGY

This systematic review was performed in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Relevant Chinese and English studies were retrieved from PubMed, Embase, Cochrane Library, Web of Science, China National Knowledge Infrastructure (CNKI), VIP database, Chinese Biomedical literature database (CBM) and Wanfang database from inception to January 9, 2023. Pooled SFGR positive rate was meta-analyzed using a random effects model and heterogeneity was assessed by the I2 index. Publication bias was also evaluated by funnel plot and Egger's test. The meta-analysis was performed on R studio 4.0.4.

PRINCIPAL FINDINGS

Meta-analysis of 57 studies published between 2000 and 2022 involving 39,380 ticks revealed a pooled SFGR positive rate of 21.4% (Q = 6423.74, I2 = 99%, Q-p<0.001, 95% CI: 15.0-29.6). Most studies of tick-borne SFGR infection rate were conducted in forest areas and developed animal husbandry areas in the northern region. There were slightly more tick species in the southern region, but the differences in tick species (Feeding tick 31.5%, 95%CI: 15.7-53.2, Questing tick 11.5%, 95%CI: 4.4-26.7, Q = 3.29, Q-p = 0.19) between areas (Northern area 20.4%, 95%CI: 14.1-28.7, Southern area 25.5%, 95%CI: 15.0-29.6, Q = 0.21, Q-p = 0.64) were not statistically significant. The most common tick species were Dermacentor silvarum (13%), Ixodes persulcatus (11%) and Haemaphysalis Iongicornis (10%), and the most prevalent SFGR species were Rickettsia raoultii (20%), Rickettsia heilongjiangiensis (11%), and some uncultured species (18%).

CONCLUSIONS

This study examined the distribution of tick-borne SFGR in China. Our findings revealed that the main tick species were D. silvarum, I. persulcatus and H. iongicornis, and the common SFGR species were R. raoultii, R. heilongjiangiensis, and some uncultured species. Further studies are warranted to identify the potential vectors of SFGR and to better understand the epidemiology and pathogenesis of tick-borne diseases in China.

Prevalence of Lyme Disease and Relapsing Fever Borrelia spp. in Vectors, Animals, and Humans within a One Health Approach in Mediterranean Countries

The genus Borrelia has been divided into Borreliella spp., which can cause Lyme Disease (LD), and Borrelia spp., which can cause Relapsing Fever (RF). The distribution of genus Borrelia has broadened due to factors such as climate change, alterations in land use, and enhanced human and animal mobility. Consequently, there is an increasing necessity for a One Health strategy to identify the key components in the Borrelia transmission cycle by monitoring the human-animal-environment interactions. The aim of this study is to summarize all accessible data to increase our understanding and provide a comprehensive overview of Borrelia distribution in the Mediterranean region. Databases including PubMed, Google Scholar, and Google were searched to determine the presence of Borreliella and Borrelia spp. in vectors, animals, and humans in countries around the Mediterranean Sea. A total of 3026 were identified and screened and after exclusion of papers that did not fulfill the including criteria, 429 were used. After examination of the available literature, it was revealed that various species associated with LD and RF are prevalent in vectors, animals, and humans in Mediterranean countries and should be monitored in order to effectively manage and prevent potential infections.

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.

The Eurasian shrew and vole tick Ixodes trianguliceps: geographical distribution, climate preference, and pathogens detected

The Eurasian shrew and vole tick Ixodes trianguliceps Birula lives in the nests and burrows of its small mammalian hosts and is-along with larvae and nymphs of Ixodes ricinus or Ixodes persulcatus-one of the most commonly collected tick species from these hosts in its Eurasian range. Ixodes trianguliceps is a proven vector of Babesia microti. In this study, up-to-date maps depicting the geographical distribution and the climate preference of I. trianguliceps are presented. A dataset was compiled, resulting in 1161 georeferenced locations in Eurasia. This data set covers the entire range of I. trianguliceps for the first time. The distribution area between 8[Formula: see text] W-105[Formula: see text] E and 40-69[Formula: see text] N extends from Northern Spain to Western Siberia. To investigate the climate adaptation of I. trianguliceps, the georeferenced locations were superimposed on a high-resolution map of the Köppen-Geiger climate classification. The Köppen profile for I. trianguliceps, i.e., a frequency distribution of the tick occurrence under different climates, shows two peaks related to the following climates: warm temperate with precipitation all year round (Cfb), and boreal with warm or cold summers and precipitation all year round (Dfb, Dfc). Almost 97% of all known I. trianguliceps locations are related to these climates. Thus, I. trianguliceps prefers climates with warm or cold summers without dry periods. Cold winters do not limit the distribution of this nidicolous tick species, which has been recorded in the European Alps and the Caucasus Mountains up to altitudes of 2400 m. Conversely, I. trianguliceps does not occur in the Mediterranean area with its hot and dry summers.

Transmission Cycle of Tick-Borne Infections and Co-Infections, Animal Models and Diseases

Tick-borne pathogens such as species of Borrelia, Babesia, Anaplasma, Rickettsia, and Ehrlichia are widespread in the United States and Europe among wildlife, in passerines as well as in domestic and farm animals. Transmission of these pathogens occurs by infected ticks during their blood meal, carnivorism, and through animal bites in wildlife, whereas humans can become infected either by an infected tick bite, through blood transfusion and in some cases, congenitally. The reservoir hosts play an important role in maintaining pathogens in nature and facilitate transmission of individual pathogens or of multiple pathogens simultaneously to humans through ticks. Tick-borne co-infections were first reported in the 1980s in white-footed mice, the most prominent reservoir host for causative organisms in the United States, and they are becoming a major concern for public health now. Various animal infection models have been used extensively to better understand pathogenesis of tick-borne pathogens and to reveal the interaction among pathogens co-existing in the same host. In this review, we focus on the prevalence of these pathogens in different reservoir hosts, animal models used to investigate their pathogenesis and host responses they trigger to understand diseases in humans. We also documented the prevalence of these pathogens as correlating with the infected ticks’ surveillance studies. The association of tick-borne co-infections with other topics such as pathogens virulence factors, host immune responses as they relate to diseases severity, identification of vaccine candidates, and disease economic impact are also briefly addressed here.

A Systematic Review of the Distribution of Tick-Borne Pathogens in Wild Animals and Their Ticks in the Mediterranean Rim between 2000 and 2021

Tick-borne pathogens (TBPs) can be divided into three groups: bacteria, parasites, and viruses. They are transmitted by a wide range of tick species and cause a variety of human, animal, and zoonotic diseases. A total of 148 publications were found on tick-borne pathogens in wild animals, reporting on 85 species of pathogens from 35 tick species and 17 wild animal hosts between 2000 and February 2021. The main TBPs reported were of bacterial origin, including Anaplasma spp. and Rickettsia spp. A total of 72.2% of the TBPs came from infected ticks collected from wild animals. The main tick genus positive for TBPs was Ixodes. This genus was mainly reported in Western Europe, which was the focus of most of the publications (66.9%). It was followed by the Hyalomma genus, which was mainly reported in other areas of the Mediterranean Rim. These TBPs and TBP-positive tick genera were reported to have come from a total of 17 wild animal hosts. The main hosts reported were game mammals such as red deer and wild boars, but small vertebrates such as birds and rodents were also found to be infected. Of the 148 publications, 12.8% investigated publications on Mediterranean islands, and 36.8% of all the TBPs were reported in seven tick genera and 11 wild animal hosts there. The main TBP-positive wild animals and tick genera reported on these islands were birds and Hyalomma spp. Despite the small percentage of publications focusing on ticks, they reveal the importance of islands when monitoring TBPs in wild animals. This is especially true for wild birds, which may disseminate their ticks and TBPs along their migration path.

Molecular Prevalence of Selected Tick-Borne Pathogens in Dermacentor reticulatus Collected in a Natural Park in Italy

Dermacentor reticulatus is one of the most important vectors of tick-borne pathogens (TBPs) in Europe causing diseases in animals and humans. A longitudinal study was planned, aimed to detect the molecular prevalence of tick-borne pathogens, i.e., Babesia spp. and the spotted fever group Rickettsiae, and its seasonal variation in D. reticulatus questing ticks to define the temporal infection risk. Ticks were collected monthly over a period of 15 months in a peri-urban park in Lombardy, Italy. DNA extraction and molecular analyses were performed. Statistical analysis was carried out. Out of 488, 53 (P = 10.9%) adult questing ticks were positive for Babesia DNA. A higher prevalence was revealed in male (32/241, P = 13.3%) than in female (21/247, P = 8.5%) ticks. Positive ticks were mostly collected in winter months (P = 13.3%) compared to early (P = 7.9) and late (P = 12.8) spring months. A similar percentage of positive ticks was evidenced in transects 1 and 3 (5.8% and 6.5%, respectively); instead, a significant higher prevalence was recorded in transect 2 (P = 16.0%). Obtained sequences confirmed a homology of 100% with B. canis sequences deposited in GenBank. No ticks tested positive for Rickettsia spp. DNA (0/488, P = 0%). The conspicuous circulation of B. canis infection in D. reticulatus adult questing ticks confirms their role in the epidemiology of canine babesiosis and requires preventive measures for dogs in this recreational area. Even if no tick was positive for the spotted fever group Rickettsia, its capacity as a vector of zoonotic pathogens should not be neglected.

Habitat suitability map of <em>Ixodes ricinus</em> tick in France using multi-criteria analysis

The tick Ixodes ricinus is widely distributed across Europe and is responsible for the transmission of several pathogens to humans and animals. In this study, we used a knowledge-based method to map variations in habitat suitability for I. ricinus ticks throughout continental France and Corsica. The multi-criteria decision analysis (MCDA) integrated four major biotic and abiotic factors known to influence tick populations: climate, land cover, altitude and the density of wild ungulates. For each factor, habitat suitability index (HSI) values were attributed to different locations based on knowledge regarding its impact on tick populations. For the MCDA, two methods of factor combination were tested, additive and multiplicative, both which were evaluated at the spatial scales of departments and local municipalities. The resulting habitat suitability maps (resolution=100x100 m) revealed that conditions are suitable for I. ricinus over most of France and Corsica. Particularly suitable habitats were located in central, north-eastern and south-western France, while less-suitable habitats were found in the Mediterranean and mountainous regions. To validate the approach, the HSI scores were compared to field data of I. ricinus nymph abundance. Regardless of scale, the correlation between abundance indicator and HSI score was stronger for the additive than for the multiplicative approach. Overall, this study demonstrates the value of MCDA for estimating habitat suitability maps for I. ricinus abundance, which could be especially useful in highlighting areas of the tick's distribution where preventive measures should be prioritised.

The bacterial biome of ticks and their wildlife hosts at the urban-wildland interface

Advances in sequencing technologies have revealed the complex and diverse microbial communities present in ticks (Ixodida). As obligate blood-feeding arthropods, ticks are responsible for a number of infectious diseases that can affect humans, livestock, domestic animals and wildlife. While cases of human tick-borne diseases continue to increase in the northern hemisphere, there has been relatively little recognition of zoonotic tick-borne pathogens in Australia. Over the past 5 years, studies using high-throughput sequencing technologies have shown that Australian ticks harbour unique and diverse bacterial communities. In the present study, free-ranging wildlife (n=203), representing ten mammal species, were sampled from urban and peri-urban areas in New South Wales (NSW), Queensland (QLD) and Western Australia (WA). Bacterial metabarcoding targeting the 16S rRNA locus was used to characterize the microbiomes of three sample types collected from wildlife: blood, ticks and tissue samples. Further sequence information was obtained for selected taxa of interest. Six tick species were identified from wildlife: Amblyomma triguttatum, Ixodes antechini, Ixodes australiensis, Ixodes holocyclus, Ixodes tasmani and Ixodes trichosuri. Bacterial 16S rRNA metabarcoding was performed on 536 samples and 65 controls, generating over 100 million sequences. Alpha diversity was significantly different between the three sample types, with tissue samples displaying the highest alpha diversity (P<0.001). Proteobacteria was the most abundant taxon identified across all sample types (37.3 %). Beta diversity analysis and ordination revealed little overlap between the three sample types (P<0.001). Taxa of interest included Anaplasmataceae, Bartonella, Borrelia, Coxiellaceae, Francisella, Midichloria, Mycoplasma and Rickettsia. Anaplasmataceae bacteria were detected in 17.7% (95/536) of samples and included Anaplasma, Ehrlichia and Neoehrlichia species. In samples from NSW, 'Ca. Neoehrlichia australis', 'Ca. Neoehrlichia arcana', Neoehrlichia sp. and Ehrlichia sp. were identified. A putative novel Ehrlichia sp. was identified from WA and Anaplasma platys was identified from QLD. Nine rodent tissue samples were positive for a novel Borrelia sp. that formed a phylogenetically distinct clade separate from the Lyme Borrelia and relapsing fever groups. This novel clade included recently identified rodent-associated Borrelia genotypes, which were described from Spain and North America. Bartonella was identified in 12.9% (69/536) of samples. Over half of these positive samples were obtained from black rats (Rattus rattus), and the dominant bacterial species identified were Bartonella coopersplainsensis and Bartonella queenslandensis. The results from the present study show the value of using unbiased high-throughput sequencing applied to samples collected from wildlife. In addition to understanding the sylvatic cycle of known vector-associated pathogens, surveillance work is important to ensure preparedness for potential zoonotic spillover events.

Research effort on birds' reservoir host potential for Lyme borreliosis: A systematic review and perspectives

Zoonotic tick-borne diseases threat human and animal health. Understanding the role of hosts in the production of infected ticks in an epidemiological system is essential to be able to design effective measures to reduce the exposure of humans and animals to infectious tick bites. The reservoir host potential, that is, number of infected ticks produced by a host species, depends on three components: tick production, realized reservoir competence and host density. The parameters and factors that determine the reservoir host potential need to be characterized to achieve a robust understanding of the dynamics of pathogen-tick-host systems, and thus to mitigate the acarological risk of emerging infections. Few studies have investigated the role of birds in the local spread of Lyme borreliosis Borrelia. Knowledge of the research effort on the reservoir host potential of birds in Lyme borreliosis Borrelia circulation is necessary to prioritize future research on this topic. We provide a systematic review of the research effort on components of the reservoir host potential of wild birds for Lyme borreliosis Borrelia circulation, and factors that modulate these components in the European epidemiological system. Our review of 242 selected publications showed that tick production has been 1.4 and 21 times more studied than realized reservoir competence and bird density respectively. Only one study achieved to characterize the global host reservoir potential of birds in a given epidemiological system. Investigated factors were mostly related to bird species identity, individual characteristics of birds and tick characteristics, whereas the influence of bird life-history traits have been largely under-investigated. Because simultaneous characterization of all parameters is notoriously complex, interdisciplinary research is needed to combine and accumulate independent field and laboratory investigations targeting each parameter on specific epidemiological system or host species. This can help gain an integrated appraisal of the functioning of the studied system at a local scale.

Ectoparasites of hedgehogs: From flea mite phoresy to their role as vectors of pathogens

Hedgehogs are synanthropic mammals, reservoirs of several vector-borne pathogens and hosts of ectoparasites. Arthropod-borne pathogens (i.e., Rickettsia spp., Borrelia spp., and Anaplasmataceae) were molecularly investigated in ectoparasites collected on hedgehogs (n = 213) from Iran (161 Hemiechinus auritus, 5 Erinaceus concolor) and Italy (47 Erinaceus europaeus). In Iran, most animals examined (n = 153; 92.2%) were infested by ticks (Rhipicephalus turanicus, Hyalomma dromedarii), and 7 (4.2%) by fleas (Archeopsylla erinacei, Ctenocephalides felis). Of the hedgehogs infested by arthropods in Italy (i.e., 44.7%), 18 (38.3%) were infested by fleas (Ar. erinacei), 7 (14.9%) by ticks (Haemaphysalis erinacei, Rh. turanicus, Rhipicephalus sanguineus sensu lato), and 6 (12.8%) by mites (Caparinia tripilis, Acarus nidicolous, Ornithonyssus spp.). Phoretic behavior of C. tripilis on Ar. erinacei was detected in two flea specimens from Italy. At the molecular analysis Rickettsia spp. was detected in 93.3% of the fleas of Italy. In Iran, Rickettsia spp. was detected in 8.0% out of 212 Rh. turanicus ticks, and in 85.7% of the Ar. erinacei fleas examined. The 16S rRNA gene for Ehrlichia/Anaplasma spp. was amplified in 4.2% of the 212 Rh. turanicus ticks. All sequences of Rickettsia spp. from fleas presented 100% nucleotide identity with Rickettsia asembonensis, whereas Rickettsia spp. from Rh. turanicus presented 99.84%–100% nucleotide identity with Rickettsia slovaca, except for one sequence, identical to Rickettsia massiliae. The sequences of the 16S rRNA gene revealed 99.57%–100% nucleotide identity with Anaplasma spp., except for one, identical to Ehrlichia spp. A new phoretic association between C. tripilis mites and Ar. erinacei fleas has been herein reported, which could be an important route for the spreading of this mite through hedgehog populations. Additionally, spotted fever group rickettsiae were herein detected in ticks and fleas, and Anaplasma/Ehrlichia spp. in ticks, suggesting that hedgehogs play a role as reservoirs for these vector-borne pathogens.

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New phoretic association of Caparinia tripilis mites on Archaeopsylla erinacei fleas.

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Occurrence of spotted fever group rickettsiae in Rhipicephalus turanicus from hedgehogs.

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Occurrence of Anaplasmataceae in Rhipicephalus turanicus from hedgehogs.

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High Prevalence of Rickettsia asembonensis in Archaeopsylla erinacei fleas from hedgehogs.

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Hedgehogs are suggested as reservoirs of vector-borne pathogens.

Rickettsiales in Italy

There is no updated information on the spread of Rickettsiales in Italy. The purpose of our study is to take stock of the situation on Rickettsiales in Italy by focusing attention on the species identified by molecular methods in humans, in bloodsucking arthropods that could potentially attack humans, and in animals, possible hosts of these Rickettsiales. A computerized search without language restriction was conducted using PubMed updated as of December 31, 2020. The Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) methodology was followed. Overall, 36 species of microorganisms belonging to Rickettsiales were found. The only species identified in human tissues were Anaplasma phagocytophilum,Rickettsia conorii, R. conorii subsp. israelensis, R. monacensis, R. massiliae, and R. slovaca. Microorganisms transmissible by bloodsucking arthropods could cause humans pathologies not yet well characterized. It should become routine to study the pathogens present in ticks that have bitten a man and at the same time that molecular studies for the search for Rickettsiales can be performed routinely in people who have suffered bites from bloodsucking arthropods.

Molecular survey on tick-borne pathogens and Leishmania infantum in red foxes (Vulpes vulpes) from southern Italy

Red foxes (Vulpes vulpes) have been recognised to harbour and transmit a wide range of tick-borne pathogens (TBPs) including those of zoonotic concern. To investigate the prevalence and the distribution of TBPs and of Leishmania infantum in foxes (n = 244), spleen samples were collected within the frame of a multi-regional wildlife health surveillance program in Italy. A combined PCR/sequencing approach was performed for the detection of Anaplasma spp., Babesia spp., Borrelia spp., Ehrlichia spp., Hepatozoon spp. and L. infantum DNA. Overall, 146 foxes (59.8 %, 95 % CI: 53.6-65.8) tested positive for at least one pathogen with Hepatozoon canis being the most prevalent (i.e., n = 124; 50.8 %, 95 % CI: 44.6-57.0), followed by Babesia vulpes (n = 20; 8.2 %, 95 % CI: 5.4-12.3), different spirochete species from Borrelia burgdorferi sensu lato complex (n = 9; 3.7 %, 95 % CI: 1.9-6.9), Ehrlichia canis and L. infantum (n = 7; 2.9 % each, 95 % CI: 1.4-5.8), Anaplasma platys (n = 4; 1.6 %, 95 % CI: 0.6-4.1), Anaplasma phagocytophilum ecotype I and Candidatus Neoehrlichia sp. (n = 3; 1.2 % each, 95 % CI: 0.4-3.5). All samples scored negative for Babesia canis and Borrelia miyamotoi. This study revealed the presence of spirochetes from B. burgdorferi s.l. complex, Ca. Neoehrlichia sp., A. platys and A. phagocytophilum ecotype I in red fox population from Italy, underling the necessity to monitoring these carnivores, mainly because they live in contact with dogs and humans. Data on the tick fauna circulating on wildlife species will complement information herein obtained, instrumentally to establish preventive strategies for minimizing the risk of infection for animals and humans.

Emergence of Lyme borreliosis in the province of Verona, Northern Italy: Five-years of sentinel surveillance

We investigated the epidemiology, clinical manifestations, laboratory data and antibiotic treatment of Lyme borreliosis in the province of Verona, Northern Italy, during the period 2015-2019. One hundred and 29 cases of Lyme borreliosis were diagnosed in a single hospital representing 27 % of all cases reported in the Veneto region in the same period. The mean annual incidence of Lyme borreliosis was 0.992/100,000 inhabitants. A peak incidence of 2/100,000 inhabitants was observed in 2018. Early localized Lyme borreliosis was the most common presentation (74 %), followed by early disseminated Lyme borreliosis (21 %). One possible early Lyme neuroborreliosis and two cranial neuropathies were diagnosed. IgM and/or IgG borrelia antibodies were positive in 90 % of the cases. This significant increase of Lyme borreliosis incidence in the province of Verona highlights the need to increase knowledge on its epidemiology and clinical manifestation among both the general population and clinicians to allow early diagnosis and treatment.

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.

Ticks climb the mountains: Ixodid tick infestation and infection by tick-borne pathogens in the Western Alps

In mountain areas of northwestern Italy, ticks were rarely collected in the past. In recent years, a marked increase in tick abundance has been observed in several Alpine valleys, together with more frequent reports of Lyme borreliosis. We then carried out a four-year study to assess the distribution and abundance of ticks and transmitted pathogens and determine their altitudinal limit in a natural park area in Piedmont region. Ixodes ricinus and Dermacentor marginatus were collected from both the vegetation and hunted wild ungulates. Tick abundance was significantly associated with altitude, habitat type and signs of animal presence, roe deer's in particular. Ixodes ricinus prevailed in distribution and abundance and, although their numbers decreased with increasing altitude, we recorded the presence of all active life stages of up to around 1700 m a.s.l., with conifers as the second most infested habitat after deciduous woods. Molecular analyses demonstrated the infection of questing I. ricinus nymphs with B. burgdorferi sensu lato (15.5 %), Rickettsia helvetica and R. monacensis (20.7 %), Anaplasma phagocytophilum (1.9 %), Borrelia miyamotoi (0.5 %) and Neoehrlichia mikurensis (0.5 %). One third of the questing D. marginatus were infected with R. slovaca. We observed a spatial aggregation of study sites infested by B. burgdorferi s.l. infected ticks below 1400 m. Borrelia-infected nymphs prevailed in open areas, while SFG rickettsiae prevalence was higher in coniferous and deciduous woods. Interestingly, prevalence of SFG rickettsiae in ticks doubled above 1400 m, and R. helvetica was the only pathogen detected above 1800 m a.s.l. Tick infestation on hunted wild ungulates indicated the persistence of tick activity during winter months and, when compared to past studies, confirmed the recent spread of I. ricinus in the area. Our study provides new insights into the population dynamics of ticks in the Alps and confirms a further expansion of ticks to higher altitudes in Europe. We underline the importance of adopting a multidisciplinary approach in order to develop effective strategies for the surveillance of tick-borne diseases, and inform the public about the hazard posed by ticks, especially in recently invaded areas.

Molecular Detection of Spotted-Fever Group Rickettsiae in Ticks Collected from Domestic and Wild Animals in Corsica, France

To obtain a better understanding of the current magnitude of tick-borne rickettsioses in Corsica, we used molecular methods to characterize the occurrence of Rickettsia spp. in ixodid ticks collected from domestic and wild animals. The presence of Rickettsia spp. was evaluated using real-time polymerase chain reaction targeting the gltA gene and by sequencing of gltA and ompA partial genes for species identification and phylogenetic analysis. Infection rates were calculated as the maximum-likelihood estimation (MLE) with 95% confidence intervals (CI). In total, 1117 ticks belonging to four genera (Rhipicephalus, Hyalomma, Ixodes, and Dermacentor) were collected from cattle, sheep, wild boars, and companion animals during July-August 2017 and July 2018-January 2019. Overall, Rickettsia DNA was detected in 208 of 349 pools of ticks (MLE = 25.6%, 95% CI: 22.6-28.8%). The molecular analysis revealed five different rickettsial species of the spotted-fever group (SFG). We highlighted the exclusive detection of Candidatus Ri. barbariae in R. bursa and of Ri. aeschlimanii in H. marginatum. Rickettsia slovaca was detected in D. marginatus collected from wild boars. This study provides the first evidence of the presence of Ri. monacensis in I. ricinus ticks isolated from a dog in Corsica. In conclusion, our data revealed wide dispersal of SFG Rickettsiae and their arthropod hosts in Corsica, highlighting the need for surveillance of the risk of infection for people living and/or working close to infected or infested animals.