Search Results (85)

Ticks are among the most important arthropod vectors affecting human and animal health worldwide. We present a set of globally harmonized indicators integrating hazard, exposure, and vulnerability associated with human-biting ticks and with two major tick-borne pathogens, Borrelia burgdorferi sensu lato (Lyme borreliosis), and Orthonairovirus haemorrhagiae (Crimean–Congo haemorrhagic fever virus, CCHFV). Hazard indices were derived from the distributions of confirmed vector tick species. Exposure was incorporated through rural human population density, livestock density, and the abundance of competent vertebrate reservoirs and/or amplification hosts, as applicable. Vulnerability was assessed using country-level indicators related to healthcare accessibility, socioeconomic development, and demographic dependency. The indices show spatially structured global patterns. Tick hazard is concentrated in eastern North America, Europe, Central and East Asia; Africa displays fragmented but substantial hotspots. The B. burgdorferi s.l. index is restricted to the Northern Hemisphere, following the distribution of Ixodes spp. and associated reservoir communities, with highest exposure in Europe and North America. The CCHFV index is confined to the Old World, extending from the Mediterranean region through the Middle East and Central Asia into Sub-Saharan Africa, reflecting the distribution of Hyalomma ticks and ungulates. The vulnerability indicators highlight regional patterns of high exposure and limited adaptive capacity, particularly in Sub-Saharan Africa and parts of the Middle East. Our framework provides the first global set of harmonized, high-resolution indices integrating vector ecology, reservoir communities, exposure, and vulnerability for major tick-borne diseases of humans. It offers a flexible platform for comparative epidemiology, surveillance prioritization, and public health decision-making at multiple administrative scales. Full article

Bacterial tick-borne pathogens (TBPs) have been reported in Latin America, but information on their prevalence in cattle and dogs in Bolivia are scant. In the present survey, blood serum samples from 95 cattle and 67 dogs living in different communities of Bolivian Chaco, a region in southeastern Bolivia, were tested for antibodies against Anaplasma phagocytophilum, Borrelia burgdorferi sensu lato (s.l.), Coxiella burnetii, Ehrlichia canis, and Rickettsia rickettsii. Indirect immunofluorescence assays detected 54/95 (56.84%) cattle sera positive to one or more pathogens: 29/95 (30.5%) to A. phagocytophilum, 27/95 (28.42%) to R. rickettsii, 5/95 (5.26%) to C. burnetii; all sera were negative to B. burgdorferi s.l. Among canine sera, 11/67 (16.41%) were positive to at least one pathogen: 2/67 (2.98%) to C. burnetii, 3/67 (4.48%) to E. canis, 6/67 (8.95%) to R. rickettsii; all sera were negative to A. phagocytophilum and B. burgdorferi s.l. To the best of our knowledge, this is the first serological survey investigating exposure to multiple TBPs in cattle and dogs from the Bolivian Chaco. Our findings suggest the circulation of A. phagocytophilum, E. canis, C. burnetii, and Spotted Fever Group Rickettsia among the animals living in this area. The results are relevant because these pathogens pose a significant threat to human and animal health and may result in substantial economic losses. Full article

Ixodidae ticks are vectors of pathogenic spirochetes from the Borrelia burgdorferi sensu lato (s.l.) complex and the relapsing fever (RF) group. The Russian Far East is endemic for borrelioses, yet data on the distribution and genetic diversity of Borrelia spp. in this region remain scarce. We examined 3107 Ixodidae ticks (Ixodes spp., Haemaphysalis spp., and Dermacentor silvarum), collected from two mainland provinces and five islands of the Russian Far East in 2005–2023. A total of 86 Borrelia afzelii, 297 Borrelia bavariensis, 81 Borrelia garinii, 44 Borrelia miyamotoi, and 33 unclassified RF borreliae were identified. Borrelia burgdorferi s.l. and B. miyamotoi were strongly associated with Ixodes spp., whereas unclassified RF borreliae were associated with Haemaphysalis spp. Among B. burgdorferi s.l. isolates, B. afzelii and B. bavariensis were found significantly more frequently in I. persulcatus compared to I. pavlovskyi, whereas B. garinii was significantly more common in I. pavlovskyi. Genetic characterization of B. burgdorferi s.l. revealed high haplotypic diversity, particularly within B. bavariensis and B. garinii. Among RF borreliae, all B. miyamotoi isolates were highly conserved and belonged to the Asian type. In contrast, unclassified RF borreliae were genetically variable and clustered with RF borreliae previously found in Haemaphysalis and Rhipicephalus ticks. The obtained results expand the understanding of the distribution and genetic diversity of Borrelia spp. in the Russian Far East. Full article

Disseminated human Lyme borreliosis is primarily associated with invasive spirochetes from the Borrelia burgdorferi sensu lato complex. Host–Borrelia interactions have been studied in a diverse range of vertebrate reservoirs. But despite the key role of the complement system in innate immunity, comparative studies evaluating the susceptibility of individual Borrelia species to human complement-mediated killing are limited. Using serum sensitivity assays, we analyzed complement-mediated killing of 10 B. burgdorferi s.l. genospecies in healthy individuals of different ages and sexes. The tested genospecies showed markedly different sensitivities to human complement. Statistical clustering divided the genospecies into three distinct groups based on whether their sensitivity to human complement was high, medium, or low. Complement resistance did not correlate with the recognized pathogenicity of the genospecies; species with unclear pathogenic potential exhibited resistance levels comparable to the major species causing human Lyme borreliosis, B. burgdorferi sensu stricto, B. afzelii and B. garinii. Females generally showed reduced complement-mediated killing compared to males. In addition, complement activity tended to decline with age, identifying host age and biological sex as important factors influencing the human innate immune response against Borrelia. Our findings suggest that the ability to evade human complement may be more widespread among Borrelia species than previously assumed. These results support an emerging model in which complement-mediated selection may shape host associations and transmission success without serving as an absolute predictor of Borrelia virulence. Full article

Background: Borrelia miyamotoi is an emerging tick-borne pathogen causing relapsing fever in humans. Although Saint Petersburg and the surrounding Leningrad Oblast harbor a high abundance of ixodid ticks (I. ricinus, I. persulcatus), no integrated assessment has yet simultaneously addressed pathogen circulation in vectors, reservoir hosts, and human populations in this specific northwestern region of Russia. Methods: During 2022–2024, we collected 1518 questing adult ticks and trapped 516 small mammals in Saint Petersburg and Leningrad Oblast. B. miyamotoi DNA was detected by real-time PCR. Sera from 3743 randomly selected volunteers (1553 from Saint Petersburg, 2190 from Leningrad Oblast) were tested for anti-B. miyamotoi IgG/IgM using a protein microarray (antigens: GlpQ, Vmps, flagellin). Infection rates and seroprevalence with 95% Wilson confidence intervals were compared using chi-square tests. Results: The overall tick infection rate was 3.78% (57/1506). I. ricinus had a significantly higher prevalence (4.94%; 95% CI: 3.67–6.60%) than I. persulcatus (2.29%; 95% CI: 1.39–3.74%; p = 0.011). Ticks from Leningrad Oblast also showed markedly elevated infection rates (4.98%; 95% CI: 3.75–6.58%) compared to those from Saint Petersburg (1.89%; 95% CI: 1.06–3.35%; p = 0.004). Small mammals exhibited substantially higher infection rates in Leningrad Oblast (39.44%; 95% CI: 31.78–47.65%) than in Saint Petersburg (13.90%; 95% CI: 10.76–17.78%; p < 0.001). Bank voles (Myodes glareolus) and yellow-necked mice (Apodemus flavicollis) were the main reservoirs; synanthropic rodents trapped within the city were found to be infected for the first time. No significant organotropism was detected, but positive correlations between infection in the heart, liver, and kidney suggested hematogenous dissemination. The overall human seroprevalence of B. miyamotoi was 1.71% (95% CI: 1.34–2.18%) and was significantly higher in Leningrad Oblast (2.19%; 95% CI: 1.66–2.89%) than in Saint Petersburg (1.03%; 95% CI: 0.64–1.67%; p = 0.010). In contrast, the seroprevalence of B. burgdorferi s. l. did not differ between the two regions (approximately 5.1%). Conclusions: This first comprehensive, multi-level investigation in Saint Petersburg and Leningrad Oblast reveals a stable epidemiological gradient: natural foci in Leningrad Oblast sustain higher B. miyamotoi circulation in ticks and rodents, which translates into a two-fold higher exposure of the rural population. The findings highlight the need to include B. miyamotoi in regional tick-borne infection surveillance programs and to adopt differentiated risk assessment strategies for urban and rural settings. Full article

As wild ungulates, including European bison, increasingly share habitats with livestock, surveillance of infectious zoonotic agents in their populations is essential for both wildlife and public health. This study aimed to screen for selected zoonotic pathogens in European bison from Poland. Samples (blood, ticks, and spleen) were collected from 86 animals. Serum was used for serological testing using commercial ELISA kits for Borrelia burgdorferi sensu lato, Brucella spp., and hepatitis E virus (HEV); ticks were analysed by real-time PCR targeting B. burgdorferi s.l., Anaplasma phagocytophilum, and Brucella spp., and spleen samples from Brucella-seropositive animals were cultured. Serological analysis revealed that 53.9% of European bison were seropositive for B. burgdorferi s.l., while 25.3% showed seroreactivity against Brucella spp.; however, these findings were not supported by molecular or culture confirmation, suggesting possible non-specific reactions or past exposure. No serum samples were positive for HEV antibodies, and no Brucella spp. were isolated from spleen samples. Molecular analysis of ticks detected B. burgdorferi s.l. DNA in 4.8% of samples and sequencing confirmed Borrelia garinii in one case. In contrast, A. phagocytophilum DNA was detected in 59.0% of ticks. No ticks tested positive for Brucella DNA. These findings indicate substantial exposure of European bison to tick-borne pathogens, particularly B. burgdorferi s.l. and A. phagocytophilum. However, Brucella seropositivity should be interpreted with caution due to the lack of molecular or culture confirmation. Full article

Tick-borne diseases are a growing public health concern in the Mediterranean. Brijuni National Park (BNP), a unique, highly visited island ecosystem characterized by increased large game host density and diverse Mediterranean habitats, presents an elevated risk for pathogen co-circulation. This study addresses the lack of spatial and epidemiological data to accurately assess human exposure risk in this environment. We performed a detailed geospatial and epidemiological risk mapping of pathogen co-circulation in BNP. A total of 587 hard ticks were collected across 26 georeferenced micro-locations (2020–2022). Ticks were morphologically identified and subsequently screened for six key zoonotic bacterial pathogens using qPCR. The Minimal Infection Rate (MIR) and a Co-infection Rate (CR) were calculated. Geographic Information System (GIS) mapping was utilized to map ecological determinants of risk. Ixodes ricinus was the overwhelmingly dominant vector (94.0%), peaking in spring, with activity absent in summer. Recorded diverse tick fauna also included Hyalomma marginatum (3%), Haemaphysalis punctata (2%), Ixodes frontalis (0.8%) and Rhipicephalus sanguineus (0.2%). Active circulation of Borrelia burgdorferi s.l. (Bbsl), Anaplasma phagocytophilum, and Ehrlichia canis were confirmed. Bbsl presented the highest MIR (3.05). The Co-infection Rate (CR) was notably high at 29.41%, with triple co-infections (Bbsl, A. phagocytophilum, E. canis) concentrated in cultivated mosaics and holm oak forests (Quercus ilex L.). The highest number of ticks was recovered from ecotone zones, accounting for 50.0% of the total catch, confirming them as high-risk interfaces. The absence of Rickettsia conorii may be attributed to the strict control/absence of its primary host (domestic dogs). The presence of the exotic vector H. marginatum was also confirmed. The high rate of co-infection and the spatial concentration of risk in specific habitats underscore an elevated and complex public health risk in BNP, closely linked to habitat structure and increased game host density. This research provides an essential geospatial framework for targeted ‘One Health’ management, prioritizing vector control in ecotone zones and dense forest refugia. Urgent surveillance for the exotic H. marginatum is warranted to monitor the potential risk of Crimean-Congo Hemorrhagic Fever. Full article

Among the 24 tick species documented in Slovakia, Ixodes ricinus is the most widespread and abundant. In some sites, 2–5 epidemiologically important tick species co-occur. Such sites represent hotspots for studying the co-circulation of tick-borne pathogens. Sympatric occurrence of five exophilic species (I. ricinus, Dermacentor reticulatus, D. marginatus, Haemaphysalis concinna, and H. inermis) was confirmed in the environs of the Žemberovce village (Levice region, south-western Slovakia). Here, the seasonal activity and abundance of questing ticks and the tick infestation of game and sheep were investigated. Questing ticks, spleens of game, and ticks removed from game and sheep were examined for the presence of tick-borne pathogens (Babesia spp., Theileria spp., Anaplasma phagocytophilum, Rickettsia spp., Borrelia burgdorferi s.l., and Borrelia miyamotoi) by molecular methods. Among the questing ticks, I. ricinus prevailed. Presence of Babesia crassa, B. microti, Rickettsia helvetica, R. raoultii, A. phagocytophilum, Borrelia afzelii, B. garinii, B. valaisiana, B. burgdorferi sensu stricto and B. miyamotoi was detected. Dermacentor marginatus, I. ricinus and H. concinna were collected from sheep. They were infected with A. phagocytophilum, A. ovis, R. slovaca, and R. raoultii. Anaplasma phagocytophilum was detected in all examined red deer and roe deer and in 55.6% of wild boar. All cervids were positive for Theileria spp. Infestation of game with all five tick species, with a predominance of I. ricinus, was confirmed. In these ticks, A. phagocytophilum, R. helvetica, R. raoultii, Babesia sp. hc-hlj212, B. crassa, B. microti, Babesia spp. and B. miyamotoi were detected. This study confirmed the presence of B. crassa in Slovakia for the first time. The investigated area, with the co-occurrence of five exophilic tick species and a wide spectrum of tick-borne pathogens, represents an epidemiologically important hotspot with the risk of infections of humans and domestic animals. Full article

Free-ranging animals may serve as sentinels for the occurrence of ticks and tick-borne pathogens within a given habitat. Between 2020 and 2022, ticks were collected from domestic animals and vegetation on a family-operated agrotouristic farm in Western Slovakia. A total of 391 ticks were obtained (163 host-feeding and 228 questing). Ixodes ricinus predominated (94.9%), followed by Dermacentor reticulatus (4.9%) and Haemaphysalis concinna (one specimen). All ticks were screened for Borrelia burgdorferi sensu lato (s.l.), Borrelia miyamotoi, Anaplasma phagocytophilum, Babesia spp., and Rickettsia spp. by using PCR-based methods and subsequent sequencing. Borrelia burgdorferi s.l. was detected in 15.9% of I. ricinus. Six species were identified, with Borrelia afzelii dominating. Borrelia miyamotoi was detected in 1.62% of questing I. ricinus. Anaplasma phagocytophilum was identified in 20.49% of I. ricinus, mainly in host-feeding specimens. Babesia spp. were detected in I. ricinus (2.7%), represented by Babesia microti, Babesia venatorum, and Babesia capreoli. Rickettsia spp. were detected in 5.39% of I. ricinus and 31.58% of D. reticulatus. They comprised Rickettsia helvetica, Rickettsia monacensis, and Rickettsia raoultii. Co-infections involving two or three pathogens were observed in several ticks. Our results underscore the considerable diversity of tick-borne pathogens in a rural area where humans and domestic animals are in close contact to wildlife. Full article

Tick-borne pathogens (TBPs) are increasingly recorded in urban areas, where synanthropic wildlife may sustain pathogen transmission cycles. The European hedgehog (Erinaceus europaeus), frequently infested with ectoparasites, may serve as an urban reservoir of zoonotic TBPs. We investigated TBPs in host tissues and associated ectoparasites (Ixodes spp. and Archaeopsylla erinacei) from 129 hedgehogs in northwestern Italy. Anaplasma phagocytophilum, Borrelia burgdorferi sensu lato and Rickettsia spp. were detected in skin, spleen and ectoparasites (Ixodes spp. and Archaeopsylla erinacei). One spleen sample was positive for B. miyamotoi. Molecular identification revealed A. phagocytophilum ecotype 1, B. afzelii and B. bavariensis. A flea-borne Rickettsia closely related to the zoonotic Rickettsia asembonensis was identified for the first time in European hedgehogs. All pathogens were more prevalent in skin than in spleen. In skin, A. phagocytophilum and B. burgdorferi s.l. showed a positive interaction, whereas both were negatively associated with Rickettsia spp. These findings highlight hedgehogs as potential urban reservoirs of zoonotic TBPs, posing a potential risk for humans and domestic animals. The marked skin tropism of these pathogens supports the use of skin for TBP surveillance and underlines its role as a key interface for vector-borne transmission. Full article

The forest fly (Hippobosca equina) is an obligate haematophagous dipteran insect (order Diptera) that primarily infests horses and may contribute to the circulation of vector-borne pathogens. This study aimed to investigate the presence of Anaplasma phagocytophilum, Borrelia burgdorferi s.l., Babesia caballi, and Theileria equi, important vector-borne pathogens of equids, in forest flies collected from horses in endemic areas of Spain. A total of 170 forest flies were collected from 39 equids across four geographical regions in Spain (Segovia, Madrid, Toledo, and Menorca) and blood samples were collected from 27 of these horses. All flies were morphologically and molecularly identified as H. equina, and DNA extracted from flies and equine blood was screened using multiplex real-time and nested PCR, followed by sequencing and phylogenetic analysis. Neither flies nor horses tested positive for A. phagocytophilum, whereas one fly was positive for B. burgdorferi s.l. (0.6%). In contrast, T. equi and B. caballi DNA were detected in 11.2% and 1.2% of flies, respectively, and all positive flies were collected from horses positive for equine piroplasmosis (T. equi/B. caballi infection), with identical 18S rRNA sequences between hosts and flies. Nested PCR showed a higher detection rate than real-time PCR for the detection of these piroplasms in flies and blood samples. These findings provide the first molecular evidence of EP pathogens in H. equina and support further investigation into the epidemiological importance of forest flies in equine pathogen surveillance. Full article

The tick species Ixodes ricinus is the most widely distributed throughout Europe and serves as the primary vector for the spirochete Borrelia burgdorferi sensu lato (s.l.), which is responsible for Lyme borreliosis. The present study evaluated the prevalence of B. burgdorferi (s.l.) in I. ricinus ticks using nPCR amplification. Ticks were collected from three geographical regions in Bulgaria: the Black Sea Coast in the east, the Pleven region in the north, and the Stara Zagora region in the central south. This study focused on urban and peri-urban areas, including heavily traveled trails in parks. The results indicated statistically significant differences in infection rates, with the highest percentage of infected ticks found in Pleven (52.34%), followed by Stara Zagora (35.46%) and the lowest on the Black Sea Coast (23.08%). Furthermore, we conducted genospecies molecular identification of B. afzelii and B. garinii by PCR amplification of genospecies-specific nucleotide sequences in the 16S rRNA gene. The lowest prevalence of B. afzelii was recorded in Stara Zagora at 10.64%, followed by the Black Sea region at 12.5%, while the statistically highest frequency was observed in Pleven at 21.03%. The prevalence of B. garinii among the total number of I. ricinus ticks was greatest in Pleven at 15.89%, followed by the Black Sea region at 8.65%, and the lowest in the Stara Zagora region at 4.96%. Statistically significant differences were found only between Pleven and Stara Zagora (p = 0.002), but no significant differences in infection rates were observed between adults and nymphs in the regions examined. Overall, the prevalence of B. afzelii in each region exceeds that of B. garinii, and when considered collectively for Bulgaria, the frequency of B. afzelii (15.9%) is higher than that of B. garinii (10.89%) in infected ticks. In a controlled epidemiological context, managing the population of I. ricinus infected with B. burgdorferi s.l. can mitigate the health burden of Lyme disease, although this preventive strategy may not guarantee complete protection. Full article

We investigated tick infestations in stray dogs from Chișinău, the capital of the Republic of Moldova, focusing on tick species distribution, and pathogen infection rates. Ticks were collected from 232 stray dogs across six major urban parks in 2021–2022. A total of 443 ticks were collected, belonging to five species: Ixodes ricinus (43.8%), Dermacentor reticulatus (35.2%), Dermacentor marginatus (20.5%), Rhipicephalus sanguineus s.l. and Haemaphysalis punctata with only 1 specimen. Notably, 92.5% of ticks were adults, while only 7% were nymphs and <1% were larvae. On average, 44.4% of stray dogs were infested with ticks, with an overall mean intensity of ~4.3 ticks per infested dog. Tick burden varied by location: dogs in large, less-maintained parks carried the most ticks. Tick pathogen screening revealed 24.4% of ticks (108/443) carried at least one pathogen. The most frequently detected were Babesia spp. in 12.2% of ticks, Borrelia burgdorferi s.l. in 7.4%, Rickettsia spp. in 3.4%, Anaplasma spp. in 2.5%, and Ehrlichia spp. in 0.5%; 4 ticks harbored co-infections. We discuss implications for public health and animal welfare and recommend control measures such as integrated stray-dog management and vegetation maintenance in urban parks. Full article

Borrelia burgdorferi sensu lato (s.l.) persistence in reservoir hosts is essential for the maintenance of the spirochaetes in the enzootic cycle. In this study, we investigated the persistence of Siberian B. burgdorferi s.l. strains in naturally infected voles and their transmission to Ixodes ticks. A long-term study conducted in 2013–2024 demonstrated the presence of Borrelia afzelii, Borrelia bavariensis, and, rarely, “Candidatus Borrelia sibirica” DNA in blood samples of small mammals. Among these, B. bavariensis exhibited the highest genetic diversity. All identified Borrelia species persisted in naturally infected Clethrionomys spp. voles throughout their lifespan (up to 50 weeks), providing the first evidence of long-term persistence of B. bavariensis and “Candidatus B. sibirica” in these hosts. Notably, the persistence of two Borrelia genospecies or several genovariants of a single genospecies within the same vole was common. Xenodiagnosis with laboratory-reared Ixodes spp. confirmed efficient transmission of all identified Borrelia genospecies to Ixodes persulcatus after 35–42 weeks of B. burgdorferi s.l. persistence. Moreover, B. bavariensis was transmitted to Ixodes pavlovskyi and I. persulcatus/I. pavlovskyi interspecies hybrids after at least 23 weeks of pathogen persistence. These findings demonstrate the reservoir competence of Clethrionomys spp. for B. afzelii, B. bavariensis, and “Candidatus B. sibirica”. Full article

This study was conducted to assess the involvement of two lizard species: the sand lizard (Lacerta agilis) and the common lizard (Zootoca vivipara), and their Ixodes ricinus ticks, in the circulation spirochetes of the Borrelia burgdorferi s.l. complex. Lizards were captured at three study sites in suburban areas of western Poland. Common lizards were less abundant and occurred only at one site. A total of 1129 ticks were collected from 167 sand lizards and 164 individuals from 42 common lizards. Biopsies of the distal part of the lizard tail were taken from 172 animals. All samples that tested positive by real-time PCR underwent subsequent nested PCR targeting the flaB gene, followed by sequencing. At least 6.3% of I. ricinus ticks (MIR) from L. agilis, and 6.1% from Z. vivipara, were infected. Borrelia lusitaniae was the most prevalent genospecies in L. agilis-derived ticks, accounting for 73.2% of all infected samples, followed by B. burgdorferi s.s. (23.0%). Conversely, this latter species prevailed (90%) over B. lusitaniae (10%) in tick samples from Z. vivipara. Therefore, we believe that sand lizards are competent reservoir hosts for B. lusitaniae, while the role of Z. vivipara for this species is unclear. The high prevalence of B. burgdorferi s.s. was also found in infected larval samples (40.7%) and biopsies (60%) of L. agilis. Thus, in our opinion, these two lizard species could be another group of reservoir hosts for this human pathogen, along with birds and rodents. Full article