Rickettsiales in the WHO European Region: an update from a One Health perspective

Microbiome-based surveillance of zoonotic tick-borne pathogens from urban wild boars in Barcelona, 2022-2023

Incursions of wild animals into urban areas amplify the potential risks of zoonotic disease transmission by increasing contact between humans and animal reservoirs. Monitoring the presence of pathogens in these animals is crucial for assessing zoonotic risks but remains challenging due to the vast array of known and unknown pathogens harboured by animals. Microbiome-based approaches provide an efficient and comprehensive alternative for monitoring microbial communities and scanning the whole spectrum of bacterial pathogens. In this study, we applied this innovative conceptual framework to implement a sentinel monitoring system for investigating zoonotic tick-borne bacteria in three tick species sampled from wild boars in the Metropolitan Area of Barcelona (MAB). Using Nanopore sequencing of the full length 16 s rRNA gene, we demonstrated a fast and cost-effective approach for microbiome analysis. Our findings revealed the presence of two pathogenic genera widely documented in ticks, encompassing five species: Rickettsia massiliae and R. slovaca, both previously detected in the area, and for the first time, Francisella tularensis -the causative agent of tularemia- as well as F. hispaniensis and Diplorickettsia massiliensis, potentially emerging patogens. Finally, our results showed distinct bacterial compositions across the tick species examined. This study highlights the sensitivity and comprehensiveness of microbiome-based surveillance of tick-borne pathogens, enabling the early detection of emerging and low-abundance bacterial species that might otherwise go unnoticed with less sensitive techniques. Such proactive detection efforts are crucial for facilitating early identification and implementing prevention strategies to mitigate zoonotic risks.

Detection of spotted fever group rickettsiae and Coxiella burnetii in long-tailed ground squirrels (Spermophilus undulatus) and their ectoparasites

Long-tailed ground squirrels (LTGRs, Spermophilus undulatus) are known as reservoirs of multiple arthropod-borne pathogens, such as Yersinia pestis and Bartonella rochalimae. However, data on the prevalence of spotted fever group rickettsiae (SFGR) and Coxiella burnetii in LTGRs and its ectoparasites are limited. In two alpine regions of Xinjiang Uygur Autonomous Region (XUAR, northwestern China), a total of 346 samples were collected from 142 LTGRs, including 142 livers and 204 pooled ectoparasites (Citellophilus tesquorum dzetysuensis: 120 pools of 484 fleas; Frontopsylla elatoides elatoides: 19 pools of 71 fleas; Neopsylla mana: 1 pool of 4 fleas; and Linognathoides urocitelli: 64 pools of 865 lice). From these samples, the DNA was extracted, followed by PCR amplification of different genetic markers. Particularly, genes encoding the outer membrane protein A and B (ompA, ompB), citrate synthase (gltA), and surface cell antigen 1 (sca1) were used to identify the SFGR. Additionly, the capsular outer membrane protein (Com1) gene and insertion sequence (IS1111) genes were used to detect Coxiella. Rickettsia sibirica subsp. sibirica, Rickettsia felis, and C. burnetii were detected in LTGRs, as well as in flea and louse pools. Rickettsia raoultii was found in LTGRs and flea pools. Furthermore, Rickettsia slovaca was also identified in the flea pools. This study provides molecular evidence for the occurrence of SFGR and C. burnetii in LTGRs and their ectoparasites. These findings suggest that R. sibirica, R. slovaca, R. raoultii, R. felis and C. burnetii are transmitted between LTGRs (as potential reservoirs) and their fleas and lice (as potential vectors).

The first direct detection of spotted fever group Rickettsia spp. diversity in ticks from Ningxia, northwestern China

BACKGROUND

Tick-borne infectious diseases caused by the spotted fever group Rickettsia (SFGR) have continuously emerging, with many previously unidentified SFGR species reported. The prevalence of SFGRs in northwestern China remains unclear. This study aimed to examine the prevalence of SFGRs and Anaplasma species by analyzing tick samples collected from the Ningxia region.

METHODS

During 2022-2023, ticks were collected from Ningxia, northwestern China, and screened using PCR to amplify target genes (16S rRNA, gltA, ompA and groEL). The amplicons were confirmed by Sanger sequencing. Single-gene sequences and concatenated sequences were used to infer phylogenetic relationships for identifying Rickettsia species.

RESULTS

Out of the 425 DNA samples, a total of 210 samples tested positive for SFGRs in ticks from Ningxia, China, with a relatively high positive rate of 49.4% (210/425). Eight spotted fever group rickettsiae and one Anaplasma species were identified and characterized, including Rickettsia raoultii (102, 24.0%), R. aeschlimannii (65, 15.3%), R. sibirica (12, 2.8%), R. slovaca (4, 0.9%), R. heilongjiangensis (1, 0.2%), Cadidatus Rickettsia hongyuanensis (4, 0.9%), Ca. R. jingxinensis (11, 2.6%), Ca. R. vulgarisii (11, 2.6%) and Anaplasma ovis (98, 23.1%). The positive rate of bacterial species ranged from 0.2% to 24.0%. Interestingly, one novel Rickettsia species, provisionally named "Candidatus Rickettsia vulgarisii", was detected in Argas ticks from Zhongwei city, which suggests the possibility of local transmission to other areas through birds. Genetic and phylogenetic analysis based on the 16S rRNA, gltA, ompA, and 17kDa genes indicated that it was divergent from all known SFG Rickettsia species but mostly related to R. vini. Different SFGR species were associated with specific tick species or genera. In addition, Anaplasma ovis was detected in two Dermacentor species, and co-infection with SFGRs was observed in 14.6% (62/425) of samples.

CONCLUSIONS

This study describes the prevalence and diversity of SFGRs in ticks from Ningxia for the first time by direct detection, reveals that Rickettsia diversity related to tick species. This data suggests that surveillance for tick-borne SFGR infections among human populations should be enhanced in this region, and further investigations on their pathogenicity to humans and domestic animals are still needed.

Ticks and Tick-Borne Pathogens in Wild Animals and Birds from Two Rehabilitation Facilities in Greece

Ticks are temporary ectoparasites that serve as vectors for a wide range of pathogens affecting both wildlife and humans. In Greece, research on the prevalence of tick-borne pathogens in wildlife is limited. This study investigates the presence of pathogens, including Anaplasma spp., Babesia spp., Bartonella spp., Rickettsia spp., as well as tick-borne encephalitis (TBE), and Crimean-Congo hemorrhagic fever (CCHF) viruses, in ticks collected from 28 wild animals across 10 different animal species. Ticks were manually harvested and identified using molecular methods, with sequencing confirming the presence of Hyalomma aegyptium, H. marginatum, H. anatolicum, Ixodes frontalis, and I. ventalloi. Among the pathogens detected, R. aeschlimannii was the most prevalent, particularly in H. aegyptium ticks from tortoises. Additionally, R. africae was identified in H. aegyptium from tortoises, marking the first report of this pathogen in this tick species in Greece. Hemolivia mauritanica, an apicomplexan parasite commonly found in Testudo tortoises, was also detected. No evidence of Babesia spp., Anaplasma spp., Bartonella spp., or viral nucleic acid was found. Phylogenetic analysis revealed close genetic relationships between the detected Rickettsia species and those previously reported in neighboring regions. These findings underscore the role of wildlife in the epidemiology of tick-borne pathogens in Greece and highlight the need for comprehensive surveillance to prevent future outbreaks.

Roles and occurrences of microbiota in the osmoregulatory organs, gills and gut, in marine medaka upon hypotonic stress

Gills and gut are the two primary osmoregulatory organs in fish. Recently, studies have expanded beyond the osmoregulatory mechanisms of these organs to explore the microbiota communities inhabiting them. It is now known that microbial communities in both organs shift in response to osmotic stress. However, there are limited studies identifying the major contributors and co-occurrence among these microbiota in both organs under seawater and freshwater transfer conditions. The current data mining report performed a bioinformatics analysis on two previous published datasets from our group, aiming to provide insights into host-bacteria relationships under osmotic stress. We divided the samples into four groups: control seawater gills (LSW); control seawater gut (TSW); freshwater transfer gills (LFW); and freshwater transfer gut (TFW). Our results showed that LSW had higher diversities, richness, and evenness compared to TSW. However, both the LFW and LSW did not show any significant differences after the freshwater transfer experiment. We further applied co-occurrence network analysis and, for the first time, reported on the interactions of taxa shaping the community structure in these two organs. Moreover, we identified enriched ectoine biosynthesis in seawater samples, suggesting its potential role in seawater environments. Increased mRNA expression levels of Na+/K+-atpase, and cftr, were observed in gills after 6 h of ectoine treatment. These findings provide a foundation for future studies on host-bacteria interactions under osmotic stress.

Identifying New Areas of Endemicity and Risk Factors for Rickettsia conorii subsp. conorii Infection: Serosurvey in Rural Areas of Romania

BACKGROUND

Mediterranean spotted fever (MSF) is an emerging tick-borne disease caused by Rickettsia conorii subsp. conorii, primarily prevalent in Mediterranean and Southern Europe. We aimed to evaluate MSF seroprevalence and risk factors in non-endemic rural areas of Romania.

METHODS

We conducted a serosurvey in five counties not under MSF surveillance by testing 459 serum samples from adult volunteers for specific IgG antibodies using ELISA. Participants answered a questionnaire regarding demographics and MSF risk factors.

RESULTS

The median age of the participants was 60 years and 329 (71.7%) were female. Overall, 64 (13.9%) samples tested positive for IgG anti-R. conorii, with rates ranging from 7.1% in Sibiu to 22.4% in Hunedoara. The median age of the positive individuals was 68 years, with a significantly higher seropositivity rate of 54.7% among those over 65 years (p = 0.01). Among those positive, 53 (82.8%) owned different household animals; 24 (37.5%) had daily contact with dogs, and 27 (42.2%) with livestock; 17 (26.6%) noted tick infestations of animals, and 23 (35.9%) reported tick bites.

CONCLUSIONS

This study revealed an important seroprevalence of MSF in Romanian areas considered non-endemic, indicating an expansion of its geographical range, probably due to climate change, and emphasizing the importance of enhanced surveillance and diagnostic capabilities nationwide.

Prevalence of tick-borne bacterial pathogens in Germany-has the situation changed after a decade?

Introduction

Tick-borne pathogens, such as Borreliella spp., Rickettsia spp., and Anaplasma spp., are frequently detected in Germany. They circulate between animals and tick vectors and can cause mild to severe diseases in humans. Knowledge about distribution and prevalence of these pathogens over time is important for risk assessment of human and animal health.

Methods

Ixodes ricinus nymphs were collected at different locations in 2009/2010 and 2019 in Germany and analyzed for tick-borne pathogens by real-time PCR and sequencing.

Results

Borreliella spp. were detected with a prevalence of 11.96% in 2009/2010 and 13.10% in 2019 with B. afzelii and B. garinii as dominant species. Borrelia miyamotoi was detected in seven ticks and in coinfection with B. afzelii or B. garinii. Rickettsia spp. showed a prevalence of 8.82% in 2009/2010 and 1.68% in 2019 with the exclusive detection of R. helvetica. The prevalence of Anaplasma spp. was 1.00% in 2009/2010 and 7.01% in 2019. A. phagocytophilum was detected in seven tick samples. None of the nymphs were positive for C. burnetii.

Discussion

Here, observed changes in prevalence were not significant after a decade but require longitudinal observations including parameters like host species and density, climatic factors to improve our understanding of tick-borne diseases.

Clinical Study and Serological Diagnosis of Vector-Borne Pathogens in Sardinian Dogs

Canine vector-borne diseases (CVBDs) comprise a group of infectious diseases caused by a wide range of pathogens transmitted by arthropod vectors. Clinical signs commonly involve symptoms such as fever, anorexia, weight loss, blood disorders, hepatosplenomegaly, and others that can lead to death in dogs with comorbidities. Some pathogens responsible for CVBDs constitute a serious threat to human health due to their zoonotic transmission. This study aimed to determine the prevalence of zoonotic vector-borne diseases (Rickettsia rickettsii, Anaplasma phagocytophilum, Ehrlichia canis, Bartonella henselae, and Leishmania infantum) in domestic Sardinian dogs with and without clinical signs of these pathogens. Blood serum samples were collected from 142 dogs and examined through serological analysis. Clinical signs suggestive of these pathogens were also evaluated. The results obtained showed that 33 (33/140; 23.6%), 22 (22/134; 16.4%), 14 (14/142; 9.9%), 20 (20/66; 30.3%), and 26 (26/108; 24.1%) dogs were seropositive for Rickettsia sp., Anaplasma sp., Ehrlichia sp., Bartonella sp., and Leishmania sp. antibodies, respectively. Among these dogs, 12 dogs presented with at least one clinical sign (8.5%), while 18 (12.7%) showed more than two symptoms at the same time. Furthermore, among the asymptomatic dogs (93/142; 65.5%), 13% (n = 12) tested positive for A. phagocytophilum, 12% (n = 11) tested positive for B. henselae, 9% (n = 8) tested positive for E. canis, 12% (n = 11) tested positive for L. infantum, and 19% (n = 18) tested positive for R. rickettsii. This survey represents the first study assessing different canine vector-borne pathogens in dogs from North Sardinia. Since the pathogens detected here represent emerging zoonotic diseases, these results highlight the need to undertake further studies to increase the knowledge of these under-reported vector-borne pathogens in Sardinia.

Leptospira spp. and Rickettsia spp. as pathogens with zoonotic potential causing acute undifferentiated febrile illness in a central-eastern region of Peru

OBJETIVE

this study was to determine the relationship between acute febrile illness and bacterial pathogens with zoonotic potential that cause emerging and re-emerging diseases in a central-eastern region of Peru.

RESULTS

Out of the 279 samples analyzed, 23 (8.2%) tested positive for infection by Rickettsia spp., while a total of 15 (5.4%) tested positive for Leptospira spp. Women had a higher frequency of infection by Rickettsia spp., with 13 cases (53.3%), while men had a higher frequency of infection by Leptospira spp., with 10 cases (66.7%). The most frequently reported general symptom was headache, with 100.0% (n = 23) of patients with Rickettsia (+) and 86.7% (n = 13) of patients with Leptospira (+) experiencing it. Arthralgia was the second most frequent symptom, reported by 95.6% (n = 22) and 60% (n = 9) of patients with Rickettsia (+) and Leptospira (+), respectively. Myalgia was reported by 91.3% (n = 21) and 66.7% (n = 10) of patients with Rickettsia (+) and Leptospira (+), respectively. Retroocular pain, low back pain, and skin rash were also present, but less frequently. Among the positives, no manifestation of bleeding was recorded, although only one positive case for Leptospira spp. presented a decrease in the number of platelets.

The application of the One Health approach in the management of five major zoonotic diseases using the World Bank domains: A scoping review

The international authorities, such as the Food and Agriculture Organization of the United Nations, World Health Organization, World Organization for Animal Health, United Nations Environment Programme, and World Bank, have endorsed the One Health concept as an effective approach to optimize the health of people, animals, and the environment. The One Health concept is considered as an integrated and unifying approach with the objective of sustainably balancing and optimizing the health of people, animals, and ecosystems. Despite variations in its definitions, the underlying principle remains consistent - recognizing the interconnected and interdependent health of humans, animals, and the environment, necessitating interdisciplinary collaboration to optimize health outcomes. The One Health approach has been applied in numerous countries for detecting, managing, and controlling diseases. Moreover, the concept has found application in various areas, including antimicrobial resistance, food safety, and ecotoxicology, with a growing demand. There is a growing consensus that the One Health concept and the United Nations Sustainable Development Goals mutually reinforce each other. The World Bank has recommended five domains as foundational building blocks for operationalising the One Health approach, which includes: i) One Health stakeholders, roles, and responsibilities; ii) financial and personal resources; iii) communication and information; iv) technical infrastructure; and v) governance. The domains provide a generalised overview of the One Health concept and guide to its application. We conducted a scoping review following the five-staged Arksey and O'Malley's framework. The objective of the review was to map and synthesise available evidence of application of the One Health approach to five major zoonotic diseases using the World Bank domains. Publications from the year 2004, marking the inception of the term 'One Health,' to 2022 were included. Information was charted and categorised against the World Bank domains identified as a priori. We included 1132 records obtained from three databases: Embase, Medline, and Global Health; as well as other sources. After excluding duplicates, screening for titles and abstracts, and full text screening, 20 articles that contained descriptions of 29 studies that implemented the One Health approach were selected for the review. We found that included studies varied in the extent to which the five domains were utilised. Less than half the total studies (45%) used all the five domains and none of the studies used all the sub-domains. The environmental sector showed an underrepresentation in the application of the One Health approach to zoonotic diseases as 14 (48%) studies in 10 articles did not mention it as a stakeholder. Sixty two percent of the studies mentioned receiving support from international partners in implementing the One Health approach and 76% of the studies were supported by international donors to conduct the studies. The review identified disparate funding mechanisms employed in the implementation of the One Health approach. However, there were limited discussions on plans for continuity and viability of these funding mechanisms in the future.

Grazing system and Hyalomma marginatum tick infestation in cattle with high prevalence of SFG Rickettsia spp

Tick-borne diseases (TBDs) represent a significant portion of infectious diseases of global public health interest. In Italy, knowledge about the occurrence of tick-borne pathogens (TBPs) in ticks parasitizing cattle is scarce. In this research, we focused on ticks infesting Maremmana cattle grazing in open pasture and silvopasture systems. After being morphologically identified, ticks were molecularly tested for the presence of pathogens of the genus Rickettsia. Of the 794 ticks detected, 117 were collected, being the majority Hyalomma marginatum (72.6%), followed by other Hyalomma species (23%), Rhipicephalus turanicus (1.7%), Rh. bursa (0.9%), Hy. lusitanicum (0.9%) and Dermatocentor marginatus (0.9%). All ticks were adults, 58.1% males and 41.8% females. The highest tick prevalence was noted in April for silvopasture system cattle (90%), and in May for open pasture ones (85%). TBPs were detected only in Hy. marginatum, and all belong to Rickettsia spp. of zoonotic interest. In particular, 21/40 (52.5%) ticks scored positive for Rickettsia spp. by gltA gene and of these 15/21 (71.4%) also to spotted fever group (SFG) rickettsiae by ompA gene. Of the total positive specimens, 19 were successfully sequenced and scored Rickettsia aeschilimannii (17/19, 89.5%), R. slovaca (1/19, 5%), and R. massiliae (1/19, 5%). This research highlights the potential impact of grazing systems on cattle parasitization by hard ticks. The molecular investigation of TBPs in ticks collected from Maremmana cattle shed light on the presence of pathogenic bacteria of SFG Rickettsia spp., pointing out the potential risk of TBPs transmission between livestock and humans.

Hazard potential of Swiss Ixodes ricinus ticks: Virome composition and presence of selected bacterial and protozoan pathogens

Ticks play an important role in transmitting many different emerging zoonotic pathogens that pose a significant threat to human and animal health. In Switzerland and abroad, the number of tick-borne diseases, in particular tick-borne encephalitis (TBE), has been increasing over the last few years. Thus, it remains essential to investigate the pathogen spectrum of ticks to rapidly detect emerging pathogens and initiate the necessary measures. To assess the risk of tick-borne diseases in different regions of Switzerland, we collected a total of 10'286 ticks from rural and urban areas in ten cantons in 2021 and 2022. Ticks were pooled according to species, developmental stage, gender, and collection site, and analyzed using next generation sequencing (NGS) and quantitative polymerase chain reaction (qPCR). The metagenomic analysis revealed for the first time the presence of Alongshan virus (ALSV) in Swiss ticks. Interestingly, the pool-prevalence of ALSV was higher than that of tick-borne encephalitis virus (TBEV). Furthermore, several TBEV foci have been identified and pool prevalence of selected non-viral pathogens determined.

The Role of Wild Boars in the Circulation of Tick-Borne Pathogens: The First Evidence of Rickettsia monacensis Presence

Most wild mammals can serve as hosts both for tick-borne pathogens (TBPs) and for the ticks themselves. Among these, wild boars, due to their large body size, habitat and life span, show high exposure to ticks and TBPs. These species are now one of the widest-ranging mammals in the world, as well as the most widespread suid. Despite the fact that certain local populations have been decimated by African swine fever (ASF), wild boars are still considered overabundant in most parts of the world, including Europe. Altogether, their long-life expectancy, large home ranges including migration, feeding and social behaviors, wide distribution, overabundance and increased chances of interactions with livestock or humans make them suitable sentinel species for general health threats, such as antimicrobial-resistant microorganisms, pollution and ASF geographical distribution, as well as for the distribution and abundance of hard ticks and also for certain TBPs, such as Anaplasma phagocytophilum. The aim of this study was to evaluate the presence of rickettsial agents in wild boars from two counties in Romania. Among 203 blood samples of wild boars (Sus scrofa ssp. attila) collected during 3 (2019-2022) hunting seasons (September-February), 15 were found positive for tick-borne pathogen DNA. Six wild boars were positive for A. phagocytophilum DNA presence and nine for Rickettsia spp. The identified rickettsial species were R. monacensis (six) and R. helvetica (three). No animal was positive either for Borrelia spp., Ehrlichia spp. or Babesia spp. To the best of our knowledge, this is the first report of R. monacensis in European wild boars, thus adding the third species from the SFG Rickettsia, in the epidemiology of which this wild species may have a role as a reservoir host.