Tick-borne rickettsioses in Europe

Tick-borne pathogens in ticks removed from humans in Northern Italy, 2018-2023

The rising prevalence and transmission of tick-borne pathogens (TBPs) represent a significant public health issue all over the world, including in Italy. The region of Lombardy, in Northern Italy, is particularly endemic for TBPs. While evidence indicates a high exposure risk to infected ticks, there is a lack of data on ticks collected from humans. Therefore, a long-term surveillance programme was implemented from 2018 to 2023 to identify selected pathogens in ticks retrieved from humans. The presence of Rickettsia spp., Borrelia burgdorferi sensu lato complex, Francisella spp., Coxiella burnetii and tick-borne encephalitis virus was evaluated. A total of 2,453 ticks were collected and most belonged to the species Ixodes ricinus (93.5 %; n = 2,293). Additionally, Ixodes spp. (n = 35), Ixodes hexagonus (n = 7), Rhipicephalus sanguineus (sensu lato) species complex (n = 16), Dermacentor spp. (n = 5), Dermacentor reticulatus (n = 7) and Dermacentor marginatum (n= 1) were identified. The nymph stage was the prevalent life stage at retrieval (n = 1,778), followed by adults (n = 443) and larvae (n = 134). Overall, 18.7 % (459/2,453) of ticks were infected with at least one pathogen and co-infections were found in 6.3 % (29/459) of the positive ticks. In the examined sample, the frequency of infection in adult ticks (90/443; 20.3 %) was higher than that observed in nymphs (335/1778; 18.8 %). The most frequently detected pathogens were Borrelia burgdorferi s.l. (10.1 %) and Rickettsia spp. (10 %). Interestingly, Francisella tularensis and Coxiella burnetii were found to be of low prevalence, suggesting a lower exposure of humans to these diseases, despite still posing a serious threat to human health due to their pathogenicity. This study raises awareness about the potential risk of tick-borne diseases in Northern Italy.

Genomic characteristics of emerging human pathogen Rickettsia aeschlimannii isolated from two Hyalomma tick species

Rickettsia aeschlimannii, which emerged in Morocco in 1997, causes the Mediterranean spotted fever-like rickettsiosis in various Mediterranean countries and recently in Russia and China. Despite its increasing distribution, no available genome has been reported outside Morocco to date. Here, we isolated two strains of R. aeschlimannii from Hyalomma asiaticum (Ning-1 strain) and Hyalomma scupense (Ning-2 strain) ticks in northwestern China and assembled their complete genomes. The genomes of the two strains were smaller than the Mediterranean MC16 strain, containing fewer pseudogenes, higher ralF virulence factor coverage, and 154 unique orthogroups. The Ning-1 strain overwhelmed the Ning-2 strain with more obvious cytopathic effects, quicker growth, and faster plaque formation in cell culture, likely due to its unique pmp20 gene, higher frequency of single nucleotide polymorphisms, and missense/silent ratio. The prevalence of R. aeschlimannii was high among Hyalomma ticks in northwestern China. These findings highlight the genomic characteristics of R. aeschlimannii and the necessity for enhanced surveillance of the emerging Rickettsia in the human population.

First Molecular Detection of Rickettsia conorii and Rickettsia helvetica in Ticks from Dogs in Luxembourg

Vector-borne diseases, particularly those caused by Rickettsia species, pose a significant public health threat in Europe. Despite extensive research on tick-borne pathogens in various European countries, Luxembourg has yet not been studied for Rickettsia spp. in ticks infesting domestic animals. This study aimed to fill this gap by investigating the presence of Rickettsia spp. in Ixodes ricinus ticks collected from domestic dogs in Luxembourg between April 2023 and April 2024. A total of 61 ticks were examined using molecular techniques, including PCR amplification of the outer membrane protein B (ompB), outer membrane protein A (ompA), and citrate synthase (gltA) genes. Results revealed the presence of R. helvetica and R. conorii subsp. raoultii, with 4.9% of ticks testing positive for Rickettsia spp. Phylogenetic analysis confirmed the high genetic identity of the sequences obtained with previously described strains from Europe and Asia. This study highlights the potential risk of emerging tick-borne diseases in Luxembourg and emphasizes the need for ongoing surveillance to better understand the spread of Rickettsia spp. in Europe, particularly as climate change may facilitate the expansion of tick populations and their associated pathogens.

[Emerging pathogens of ocular infections due to environmental changes-What lies ahead?]

Due to the global effects of climate change numerous infectious diseases are increasingly spreading to regions that were previously hardly or only slightly affected. As ocular involvement is possible in many of these infectious diseases, we must also adapt to new pathogens and clinical pictures in Germany in the medium to long term. Using selected bacterial, viral and mycotic pathogens and diseases as examples, the causes of the increase in dissemination and the consequences for ophthalmology are presented.

Update on tick-borne rickettsioses in mainland Portugal: emerging threats and potential vectors

BACKGROUND

Tick-borne rickettsioses (TBR) are emerging, neglected, zoonoses, caused by intracellular α-proteobacteria of the genus Rickettsia, that pose a growing public health concern. The aim of the present study was to evaluate rickettsial infections in questing ticks collected from four different ecological areas in mainland Portugal.

METHODS

Over a two-year period, a total of 707 questing ticks were collected. Individual adult ticks and pooled nymphs were submitted to DNA extraction, followed by qPCR assays targeting the gltA rickettsial gene. Positive samples were then submitted to conventional PCR targeting the gltA and the ompA genes for phylogenetic analysis.

RESULTS

In total, eight tick species were identified: Dermacentor marginatus, Haemaphysalis inermis, Haemaphysalis punctata, Hyalomma lusitanicum, Ixodes frontalis, Ixodes ricinus, Rhipicephalus pusillus, and Rhipicephalus sanguineus sensu lato. Additionally, rickettsial infection was associated with seven of these species, with I. frontalis being the exception. Notably, the prevalence of Rickettsia spp. was 26.35%, with phylogenetic validation confirming infections with R. helvetica, R. massiliae, R. monacensis, Candidatus R. rioja, and R. slovaca.

CONCLUSIONS

The present study highlights the necessity for ongoing surveillance to map and monitor both questing and feeding ticks, along with their vertebrate hosts. Effective control strategies are of utmost importance to mitigate the escalating threat of TBR. Additionally, the present study provides valuable epidemiological insights into TBR in Portugal, including the identification of R. slovaca infecting I. ricinus - an unconventional tick-pathogen relationship - and the first report of Candidatus R. rioja infecting D. marginatus in Portugal. In conclusion, this study contributes with valuable data regarding epidemiological results on ticks and TBR circulating in Portugal, emphasizing the importance of proactive measures to address this emerging public health challenge.

Nationwide Survey of Vector-Borne Diseases in Rodents and Mites in Korea: Anaplasma, Ehrlichia, and Rickettsia

Rodents are reservoirs for zoonotic pathogens, making it essential to study both rodents and their ectoparasites. In 2022 and 2023, we investigated the spatial distribution of rodents and their mites across Korea, focusing on three vector-borne diseases (VBDs): Anaplasma, Ehrlichia, and Rickettsia. A total of 835 wild rodents were collected from 16 locations, each consisting of five distinct environmental settings (mountains, waterways, reservoirs, fields, and paddy fields), with 20 traps per setting, totaling 100 Sherman live folding traps per site. Each rodent was identified using a taxonomic key, and post-mortem examinations led to the collection of 7971 mites (498 pools), followed by PCR analysis. Among the rodents, Anaplasma phagocytophilum was detected in 10.3%, Ehrlichia muris in 0.5%, Ehrlichia ruminantium in 0.2%, and Rickettsia raoultii in 2.9%. In mites, A. phagocytophilum was found in 8.8%, E. muris in 0.2%, R. raoultii in 0.2%, R. endosymbiont in 1.6%, and R. australis in 1.2%. This study marks the first detection of E. muris and R. raoultii in Korean rodents and the first global discovery of E. ruminantium in rodents. The detection of multiple pathogens in mites worldwide highlights the importance of continuous VBD monitoring to mitigate public health risks.

Temporal dynamics of the Hyalomma marginatum-borne pathogens in southern France

Spatio-temporal scales have a clear influence on microbial community distribution and diversity and should thus be applied to study the dynamics of microorganisms. The invasive tick species Hyalomma marginatum has recently become established in southern France. It may carry pathogens of medical and veterinary interest including the Crimean-Congo haemorrhagic fever virus, Rickettsia aeschlimannii, Theileria equi and Anaplasma phagocytophilum. Pathogenic communities of H. marginatum have been identified and their spatial distribution characterized, but their temporal dynamics remain unknown. Hyalomma marginatum ticks were collected from hosts at monthly intervals from February to September 2022 in a site in southern France to study their presence and temporal dynamics. Of the 281 ticks analysed, we detected pathogens including R. aeschlimannii, Anaplasma spp. and T. equi with infection rates reaching 47.0%, 4.6% and 11.0%, respectively. A total of 14.6% of ticks were infected with at least Theileria or Anaplasma, with monthly fluctuations ranging from 2.9% to 28.6%. Strong temporal patterns were observed for each pathogen detected, particularly for R. aeschlimannii, whose infection rates increased dramatically at the beginning of summer, correlated with monthly mean temperatures at the site. Based on these results, we hypothesise that R. aeschlimannii may be a secondary symbiont of H. marginatum and could be involved in the stress response to temperature increase and mediate thermal tolerance of H. marginatum. Analysis of monthly and seasonal fluctuations in pathogens transmitted by H. marginatum led us to conclude that the risk of infection is low but persists throughout the period of H. marginatum activity, with a notable increase in summer.

Ticks and Tick-Borne Pathogens: Occurrence and Host Associations over Four Years of Wildlife Surveillance in the Liguria Region (Northwest Italy)

Tick-borne diseases (TBDs) are a considerable public health problem worldwide. The occurrence of Anaplasma spp., Borrelia burgdorferi s.l., Coxiella burnetii, Rickettsia spp., and tick-borne encephalitis virus (TBEv) was investigated via PCR and sequencing in 683 ticks collected from 105 roe deer, 61 wild boars, 49 fallow deer, and 2 chamois, in the Liguria region, northwest Italy, between 2019 and 2022. The ticks were morphologically identified. Four different tick species were found: Ixodes ricinus (66.8% of the collected ticks), Dermacentor marginatus (15.8%), Rhipicephalus sanguineus s.s. (15.7%), and Haemaphysalis punctata (0.9%). Six ticks (0.9%) were only identified as Rhipicephalus spp. Of the 222 pools analyzed, 27.9% were positive. Most pools (n = 58, 26.1% of pools analyzed) were positive for Rickettsia spp., and several species were found: Rickettsia slovaca was the dominant species (15.3%), followed by R. monacensis (8.1%), while R. helvetica (1.8%), R. massiliae (0.5%), and R. raoultii (0.5%) were found only sporadically. Anaplasma phagocytophilum was identified in three pools and B. burgdorferi s.l. in one pool. All samples were negative for C. burnetii and TBEv. Significant associations were found between I. ricinus and roe deer, D. marginatus and wild boar, and between R. monacensis and I. ricinus. The prevalence of Rickettsia spp. differed significantly between tick and host species. This updated picture of tick species and TBPs in wild ungulates in Liguria, where the population of these animals is increasing, shows a widespread presence of potentially zoonotic Rickettsia spp. Continuous monitoring and public information on preventive measures are needed.

Identification of Rickettsia spp. in Ticks Removed from Tick-Bitten Humans in Northwestern Spain

Tick-borne rickettsioses (TBRs) are distributed worldwide and are recognized as important emerging vector-borne zoonotic diseases in Europe. The aim of this study was to identify tick-associated Rickettsia among ticks removed from humans, and to track how tick populations and their associated pathogens have changed over the years. For this purpose, we conducted a tick surveillance study in northwestern Spain between 2018 and 2022. Ticks were morphologically identified and analyzed for the presence of rickettsial pathogens through the amplification of the citrate synthase (gltA) and the outer membrane protein A (ompA) genes. PCR products were sequenced and subjected to phylogenetic analyses. We collected 7397 ticks, with Ixodes ricinus being the species most frequently isolated. Based on the PCR results, Rickettsia DNA was detected in 1177 (15.91%) ticks, and 10 members of Rickettsia were identified: R. aeschlimannii, R. conorii subsp. conorii, R. conorii subsp. raoultii, R. massiliae, R. monacensis, R. sibirica subsp. mongolitimonae, R. slovaca, R. helvetica, Candidatus R. barbariae, and Candidatus R. rioja. Some of these Rickettsia have gone previously undetected in the study region. There is clear geographic and seasonal expansion not only of tick populations, but also of the associated Rickettsia. The comparison of our data with those obtained years ago provides a clear idea of how the spatiotemporal distributions of ticks and their associated Rickettsiae have changed over the years.

The influence of forest habitat type on Ixodes ricinus infections with Rickettsia spp. in south-western Poland

This study investigates the prevalence of Rickettsia spp. in Ixodes ricinus tick populations in different forest habitat types (broadleaf forest, mixed broadleaf and coniferous forest, and coniferous forest) in south-western Poland. During the survey periods from April to June 2018 and 2019 a total of 494 I. ricinus ticks, including 374 nymphs, 60 females and 60 males, were tested for Rickettsia infections by nested PCR targeting the gltA gene. The overall infection rate was 42.3%; however, we observed statistically significant year-to-year variation. Infection rates varied between tick developmental stages and were significantly influenced by forest habitat type. As assessed by a generalized linear mixed model (GLMM), the highest infection rates were observed in mixed broadleaf and coniferous forests, while coniferous forests had a significant negative effect on infection prevalence. DNA sequencing of selected samples confirmed the predominance of Rickettsia helvetica (91.2%) and less frequent Rickettsia monacensis (8.8%). This study suggests that the forest habitat types can influence Rickettsia spp. infection in tick populations; however, a comprehensive understanding of all factors influencing the level of infection requires future study.

Tick-Borne Bacterial Diseases in Europe: Threats to public health

BACKGROUND

Tick-borne diseases, caused by bacterial pathogens, pose a growing threat to public health in Europe. This paper provides an overview of the historical context of the discovery of the most impactful pathogens transmitted by ticks, including Borrelia burgdorferi sensu lato, Rickettsia spp., Anaplasma spp., Francisella spp., Ehrlichia spp., and Neoehrlichia mikurensis. Understanding the historical context of their discovery provides insight into the evolution of our understanding of these pathogens.

METHODS AND RESULTS

Systematic investigation of the prevalence and transmission dynamics of these bacterial pathogens is provided, highlighting the intricate relationships among ticks, host organisms, and the environment. Epidemiology is explored, providing an in-depth analysis of clinical features associated with infections. Diagnostic methodologies undergo critical examination, with a spotlight on technological advancements that enhance detection capabilities. Additionally, the paper discusses available treatment options, addressing existing therapeutic strategies and considering future aspects.

CONCLUSIONS

By integrating various pieces of information on these bacterial species, the paper aims to provide a comprehensive resource for researchers and healthcare professionals addressing the impact of bacterial tick-borne diseases in Europe. This review underscores the importance of understanding the complex details influencing bacterial prevalence and transmission dynamics to better combat these emerging public health threats.

Anaplasma platys and Rickettsia massiliae in Rhipicephalus sanguineus sensu stricto ticks collected on dogs in the Patagonian region of Argentina

The aim of this study was to examine the presence of tick-borne rickettsial bacteria in Rhipicephalus sanguineus sensu stricto ticks collected from dogs in the Patagonian region of Argentina. Fourteen stray dogs from Valcheta, Río Negro province, Argentina were examined for the presence of R. sanguineus s.s. ticks. Ninety ticks were collected and identified to species level. DNA was extracted and analysed by conventional PCR assays for the presence of tick-borne bacteria belonging to the genera Anaplasma, Ehrlichia and Rickettsia. Thirty-three tick pools were tested by different PCR assays of which 3 were positive for Anaplasmataceae bacteria. From the 3 Anaplasmataceae positive samples, 2 partial 16S rDNA sequences were generated and belonging to Anaplasma platys, the causative agent of canine cyclic thrombocytopenia. Two tick samples were positive in Rickettsia specific PCR assays and were identified by phylogenetic analysis as Rickettsia massiliae, a member of the spotted fever group rickettsiae. The results of this study demonstrate the molecular detection of 2 rickettsial bacteria in R. sanguineus s.s. in a region of Argentina where no data were available so far.

Diversity of Rickettsia species in collected ticks from Southeast Iran

Rickettsia occurs worldwide and rickettsiosis is recognized as an emerging infection in several parts of the world. Ticks are reservoir hosts for pathogenic Rickettsia species in humans and domestic animals. Most pathogenic Rickettsia species belong to the spotted Fever Group (SFG). This study aimed to identify and diagnose tick fauna and investigate the prevalence of Rickettsia spp. in ticks collected from domestic animals and dogs in the rural regions of Kerman Province, Southeast Iran. In this study, tick species (fauna) were identified and 2100 ticks (350 pooled samples) from two genera and species including Rhipicephalus linnaei (1128) and Hyalomma deteritum (972) were tested to detect Rickettsia genus using Real-time PCR. The presence of the Rickettsia genus was observed in 24.9% (95%CI 20.28-29.52) of the pooled samples. Sequencing and phylogenetic analyses revealed the presence of Rickettsia aeschlimannii (48.98%), Rickettsia conorii israelensis (28.57%), Rickettsia sibirica (20.41%), and Rickettsia helvetica (2.04%) in the positive samples. The results showed a significant association between county variables and the following variables: tick spp. (p < 0.001), Rickettsia genus infection in ticks (p < 0.001) and Rickettsia spp. (p < 0.001). In addition, there was a significant association between tick species and host animals (dogs and domestic animals) (p < 0.001), Rickettsia spp infection in ticks (p < 0.001), and Rickettsia spp. (p < 0.001). This study indicates a high prevalence of Rickettsia spp. (SFG) in ticks of domestic animals and dogs in rural areas of Kerman Province. The health system should be informed of the possibility of rickettsiosis and the circulating species of Rickettsia in these areas.

Tick-borne bacterial agents in Hyalomma asiaticum ticks from Xinjiang Uygur Autonomous Region, Northwest China

BACKGROUND

Hyalomma ticks are widely distributed in semi-arid zones in Northwest China. They have been reported to harbor a large number of zoonotic pathogens.

METHODS

In this study, a total of 334 Hyalomma asiaticum ticks infesting domestic animals were collected from four locations in Xinjiang, Northwest China, and the bacterial agents in them were investigated.

RESULTS

A putative novel Borrelia species was identified in ticks from all four locations, with an overall positive rate of 6.59%. Rickettsia sibirica subsp. mongolitimonae, a human pathogen frequently reported in Europe, was detected for the second time in China. Two Ehrlichia species (Ehrlichia minasensis and Ehrlichia sp.) were identified. Furthermore, two Anaplasma species were characterized in this study: Candidatus Anaplasma camelii and Anaplasma sp. closely related to Candidatus Anaplasma boleense. It is the first report of Candidatus Anaplasma camelii in China.

CONCLUSIONS

Six bacterial agents were reported in this study, many of which are possible or validated pathogens for humans and animals. The presence of these bacterial agents may suggest a potential risk for One Health in this area.

Seasonal pattern of questing ticks and prevalence of pathogenic Rickettsia and Anaplasmataceae in Khao Yai national park, Thailand

BACKGROUND

Tick-borne diseases (TBD) are considered neglected diseases in Thailand with disease burden likely underestimated. To assess risk for emerging TBD in Thailand, the seasonality of questing tick and pathogen prevalence were studied in Khao Yai National Park, a top tourist destination.

METHODS

During 2019, questing ticks around tourist attractions were systematically collected bimonthly and analyzed for Rickettsia and Anaplasmataceae bacterial species by polymerase chain reaction and DNA sequencing.

RESULTS

Larvae and nymphs of questing ticks peaked in Khao Yai National Park during the late rainy-winter season, though no specific trends were observed in adult ticks. Winter (November to February) was the highest risk for human tick-bites due to higher numbers of both ticks and visitors. Of the total 5916 ticks analyzed (651 pools), Anaplasma phagocytophilum, Neoehrlichia mikurensis, Ehrlichia ewingii, and Ehrlichia chaffeensis were detected at low rates (≤0.05%). There was a higher prevalence of human rickettsioses (0.2-7%) in ticks surveyed with Rickettsia tamurae, Rickettsia raoultii, and Rickettsia montana the major species. Amblyomma ticks had the highest prevalence of Rickettsia (85%, 35/44 Amblyomma adults), in which only R. tamurae and R. raoultii were found in Amblyomma with mixed species infections common. We report the first detection of R. africae-like and N. mikurensis in Ixodes granulatus adults in Thailand, suggesting I. granulatus as a potential vector for these pathogens.

CONCLUSION

This study demonstrated the risk of emerging TBD in Thailand and underscores the need for tick-bite prevention among tourists in Thailand.

Scalp eschar and neck lymph adenopathy after a tick bite (SENLAT) in Tuscany, Italy (2015-2022)

INTRODUCTION

The Scalp Eschar and Neck Lymph Adenopathy After a Tick Bite (SENLAT) syndrome is frequently caused by Rickettsia slovaca and Rickettsia raoultii. Only six microbiologically confirmed SENLAT cases have been reported in Italy between 1996 and 2021. We report ten cases of SENLAT seen between 2015 and 2022 in a tertiary care center in Tuscany, Italy.

CASES PRESENTATION

All patients were women; most common symptoms were scalp eschar on the site of tick bite (100%) and cervical lymphadenopathy (90%). No microbiological identification was obtained. Persistent alopecia, for several months to years, was observed in four patients. The known difficulty of microbiological diagnosis in SENLAT was worsened, in our cases, by factors as the absence of ticks available for identification and microbiological study, and antibiotic treatment administration previous to microbiological tests.

CONCLUSION

The report highlights the presence of SENLAT in Italy, aiming to raise the awareness toward the emergence of this clinical entity.

Serological profile of patients suspected with non-scrub typhus rickettsioses

BACKGROUND

Rickettsial pathogens are Gram-negative, obligate intracellular bacteria. They are transmitted by arthropods and are responsible for a wide variety of disease, from minor to life-threatening, which have a global effect on human health. Limited data are available on the prevalence of rickettsial diseases from India, and the disease epidemiology is not fully described. This study aimed to diagnose non-scrub typhus rickettsioses including spotted fever and typhus group of Rickettsia in clinically suspected patients by using standard serological tests and recognition of common epidemiological conditions and clinical manifestations.

METHODS

During the study period, a total of 700 patients of all ages with acute febrile illness were enrolled. Patients were screened for rickettsial infection using IgM Enzyme-linked immunosorbent assay (ELISA) and Immunofluorescence assay (IFA) was performed to confirm the ELISA positive results. The relevant demographic, clinical, and laboratory details of patients were documented and analyzed.

RESULTS

Of 700 samples tested, 141 (20.2%) were found to be positive for IgM antibodies against rickettsioses using ELISA and IFA. SFGR was positive in 15 (2.2%), TGR was positive in 112 (16%) and 14 (2%) samples were positive for both groups. 20 (14.2%) patients required admission to the intensive care unit (ICU), and 24 (17%) in-hospital deaths occurred.

CONCLUSIONS

The prevalence of rickettsioses in India appears to be underestimated; therefore, increased awareness and improved diagnostic testing could facilitate early detection of cases, pathogen-targeted appropriate treatment, and improved outcomes for patients. Despite the fact that Rickettsiae can be isolated or detected using molecular techniques in clinical specimens, serology still remains the most commonly used diagnostic method for rickettsioses around the world. Our study helps bridge the gap of limited data on Rickettsia in north India and could be useful for future epidemiological investigation of rickettsial diseases and outbreaks.

Exploring the diversity of tick-borne pathogens: The case of bacteria (Anaplasma, Rickettsia, Coxiella and Borrelia) protozoa (Babesia and Theileria) and viruses (Orthonairovirus, tick-borne encephalitis virus and louping ill virus) in the European continent

Ticks are the main vectors for the transmission of bacterial, protist and viral pathogens in Europe affecting wildlife and domestic animals. However, some of them are zoonotic and can cause serious, sometimes fatal, problems in human health. A systematic review in PubMed/MEDLINE database was conducted to determine the spatial distribution and host and tick species ranges of a selection of tick-borne bacteria (Anaplasma spp., Borrelia spp., Coxiella spp., and Rickettsia spp.), protists (Babesia spp. and Theileria spp.), and viruses (Orthonairovirus, and flaviviruses tick-borne encephalitis virus and louping ill virus) on the European continent in a five-year period (November 2017 - November 2022). Only studies using PCR methods were selected, retrieving a total of 429 articles. Overall, up to 85 species of the selected tick-borne pathogens were reported from 36 European countries, and Anaplasma spp. was described in 37% (159/429) of the articles, followed by Babesia spp. (34%, 148/429), Borrelia spp. (34%, 147/429), Rickettsia spp. (33%, 142/429), Theileria spp. (11%, 47/429), tick-borne flaviviruses (9%, 37/429), Orthonairovirus (7%, 28/429) and Coxiella spp. (5%, 20/429). Host and tick ranges included 97 and 50 species, respectively. The highest tick-borne pathogen diversity was detected in domestic animals, and 12 species were shared between humans, wildlife, and domestic hosts, highlighting the following zoonotic species: Anaplasma phagocytophilum, Babesia divergens, Babesia microti, Borrelia afzelii, Borrelia burgdorferi s.s., Borrelia garinii, Borrelia miyamotoi, Crimean-Congo hemorrhagic fever virus, Coxiella burnetii, Rickettsia monacensis and tick-borne encephalitis virus. These results contribute to the implementation of effective interventions for the surveillance and control of tick-borne diseases.

Rickettsial Infection in the COVID-19 Era: The Correlation between the Detection of Rickettsia aeschlimannii in Ticks and Storytelling Photography of a Presumable Human Rickettsiosis Case

Rickettsia aeschlimannii infection is an emerging human tick-borne disease with only a few recorded cases. We reported a presumable autochthonous case of rickettsiosis in an Italian cattle breeder associated with a Hyalomma marginatum bite. Rickettsia aeschlimannii DNA was detected in both the tick specimen from the patient and the grazing cattle close to his farm.

Tick-borne pathogens in ticks from urban and suburban areas of north-western Spain: Importance of Ixodes frontalis harbouring zoonotic pathogens

To identify the questing tick populations in urban and suburban areas from the city of Lugo (NW Spain), ticks were collected monthly by flagging. The presence of Borrelia spp., Rickettsia spp. and Anaplasma phagocytophilum also was determined by polymerase chain reaction (PCR) and sequence analysis. Overall, 342 questing ticks were collected; the tick abundance was higher in suburban (95.9%) than in urban areas (4.1%). Ixodes frontalis was the most abundant (86.5%); 88.5% were larvae, 11.1% nymphs and 0.3% adults. All development stages of I. ricinus (7.3%) and adults of Rhipicephalus sanguineus sensu lato (5.8%) and Dermacentor reticulatus (0.3%) were found. Rickettsia spp. (31.9%) was more prevalent than Borrelia spp. (2.7%); no ticks were positive to A. phagocytophilum. Six Rickettsia species were identified (R. slovaca, R. monacensis, R. massiliae, R. raoultii, R. sibirica subsp. mongolitimonae and R. aeschielmanii); Candidatus Rickettsia rioja and two novel Rickettsia species also were detected. In addition, Borrelia turdi (1.8%) and B. valaisiana (0.9%) were identified in Ixodes ticks. This is the first report of R. slovaca in R. sanguineus s.l. and of R. monacensis, R. raoultii, R. slovaca, R. sibirica subsp. mongolitimonae and Ca. R. rioja in I. frontalis. Since most of the pathogens detected are zoonotic, their presence in these areas may have implications for public health.

Molecular detection of Rickettsia spp. in wild ungulates and their ticks in Mediterranean areas of southwestern Spain

Wildlife is an important reservoir of zoonotic pathogens. The objective of the present study was to assess the importance of wild ungulates in the epidemiology of Rickettsia spp. Ticks and spleen samples were collected from 262 red deer (Cervus elaphus) and 83 wild boar (Sus scrofa) hunted in southwestern Spain over a 5-year period. DNA was extracted from tick pools (n = 191) and spleens (n = 345), and two nested PCR assays targeting the rOmpA and rOmpB genes were used to detect Rickettsia DNA. Five tick species were identified (Hyalomma lusitanicum, Dermacentor marginatus, Ixodes ricinus, Rhipicephalus bursa and Haemaphysalis sulcata). Rickettsia DNA was detected in 31 (16.2%) tick pools and two red deer spleen samples (0.8%). Four validated Rickettsia species (R. slovaca, R. monacensis, R. helvetica and R. raoultii), one uncultivated species (Candidatus R. rioja) and two uncharacterized Rickettsia spp. were detected in ticks. R. helvetica and R. slovaca were also detected in spleen samples from red deer. The overall prevalence in ungulate spleen samples was lower than in tick pools suggesting that these ungulates do not play a major role in the transmission of Rickettsia spp. However, their importance as spreaders of positive ticks cannot be ruled out. The results present a challenge for the veterinary and public health communities since most of the Rickettsia spp. detected are pathogenic. Furthermore, the new Rickettsia species could be potential pathogens. For these reasons, identifying Rickettsia species present in ticks and wildlife is of particular interest to clarify their sylvatic cycle and establish appropriate control measures.

Tick-borne diseases under the radar in the North Sea Region

The impact of tick-borne diseases caused by pathogens such as Anaplasma phagocytophilum, Neoehrlichia mikurensis, Borrelia miyamotoi, Rickettsia helvetica and Babesia species on public health is largely unknown. Data on the prevalence of these pathogens in Ixodes ricinus ticks from seven countries within the North Sea Region in Europe as well as the types and availability of diagnostic tests and the main clinical features of their corresponding diseases is reported and discussed. Raised awareness is needed to discover cases of these under-recognized types of tick-borne disease, which should provide valuable insights into these diseases and their clinical significance.

Doxycycline responding illnesses in returning travellers with undifferentiated non-malaria fever: a European multicentre prospective cohort study

BACKGROUND

Diagnosis of undifferentiated non-malaria fevers (NMF) in returning travellers is a great challenge. Currently, there is no consensus about the use of empirical antibiotics in returning travellers with undifferentiated NMF. Although studies in endemic areas showed that a wide range of pathogens implicated in undifferentiated NMF are treatable with doxycycline, the role of doxycycline in returning travellers with fever still has to be explored.

METHODS

Prospective European multicentre cohort study of febrile international travellers (November 2017-November 2019). Immunological and molecular diagnostic techniques for doxycycline responding illnesses (DRI) agents such as Anaplasma phagocytophilum, spotted fever group Rickettsia spp., typhus group Rickettsia spp., Coxiella burnetii, Bartonella spp., Orientia tsutsugamushi, Borrelia miyamotoi, Borrelia recurrentis and Leptospira spp. were systematically performed in all patients with undifferentiated NMF. We estimated the prevalence and predictive factors of DRI in returning travellers with undifferentiated NMF.

RESULTS

Among 347 travellers with undifferentiated NMF, 106 (30·5%) were finally diagnosed with DRI. Only 57 (53·8%) of the 106 DRI infections were diagnosed by the standard of care. The main causes of DRI were: 55 (51·9%) Rickettsia spp., 16 (15·1%) C. burnetii; 15 (14·2%) Bartonella spp.; 13 (12·3%) Leptospira spp. and 10 (9·5%) A. phagocytophilum. The only predictive factor associated with DRI was presenting an eschar (aOR 39·52, 95%CI 4·85-322·18). Features of dengue such as retro-orbital pain (aOR 0·40, 95%CI 0·21-0·76) and neutropenia (aOR 0·41, 95%CI 0·21-0·79) were negatively associated with DRI.

CONCLUSIONS

Although DRI are responsible for 30% of undifferentiated NMF cases in travellers, those are seldom recognized during the first clinical encounter. Empirical treatment with doxycycline should be considered in returning travellers with undifferentiated fever and negative tests for malaria and dengue, particularly when presenting severe illness, predictive factors for rickettsiosis or no features of dengue.

First Records of Possibly Human Pathogenic Rickettsia Species in Bat Ticks, Carios vespertilionis, in Sweden

The Soprano pipistrelle bat, Pipistrellus pygmaeus, is a common species in large parts of Sweden. Many of its natural habitats are near human habitations. This creates opportunities for ticks infesting these bats to encounter humans and possibly transmit zoonotic pathogens by tick bites. The bats are often infested with Carios vespertilionis, a tick species that, in addition to bats, has been recorded to bite humans on occasion. This study aimed to investigate if C. vespertilionis acts as a reservoir for Anaplasma phagocytophilum, Neoehrlichia mikurensis, Tick-borne encephalitis virus, and species of Babesia and Rickettsia and to improve currently used conventional PCR protocols for molecular species determination of Rickettsia spp. Ninety-two C. vespertilionis ticks were collected from underneath a bat-box harbouring P. pygmaeus. Pathogen-specific PCR assays showed that 58.4% were positive for Rickettsia spp. and negative for the other pathogens analysed. Phylogenetic analyses indicate that the species belong to R. parkeri, R. conorii, R. slovaca, R. sibirica subsp. mongolotimonae, R. rickettsii, and a hitherto uncultured Rickettsia sp. Several of these species are considered pathogenic to humans. Given the ecology and behaviour of C. vespertilionis, it may be a vector of these rickettsiae among bats and occasionally humans. To determine the Rickettsia species with certainty, and to determine if C. vespertilionis may be a reservoir and vector of the Rickettsia spp., further studies are needed.

Update on Accepted Novel Bacterial Isolates Derived from Human Clinical Specimens and Taxonomic Revisions Published in 2020 and 2021

A number of factors, including microbiome analyses and the increased utilization of whole-genome sequencing in the clinical microbiology laboratory, has contributed to the explosion of novel prokaryotic species discovery, as well as bacterial taxonomy revision. This review attempts to summarize such changes relative to human clinical specimens that occurred in 2020 and 2021, per primary publication in the International Journal of Systematic and Evolutionary Microbiology or acceptance on Validation Lists published by the International Journal of Systematic and Evolutionary Microbiology. Of particular significance among valid and effectively published taxa within the past 2 years were novel Corynebacterium spp., coagulase-positive staphylococci, Pandoraea spp., and members of family Yersiniaceae. Noteworthy taxonomic revisions include those within the Bacillus and Lactobacillus genera, family Staphylococcaceae (including unifications of subspecies designations to species level taxa), Elizabethkingia spp., and former members of Clostridium spp. and Bacteroides spp. Revisions within the Brucella genus have the potential to cause deleterious effects unless the relevance of such changes is properly communicated by microbiologists to stakeholders in clinical practice, infection prevention, and public health.

Revealing the Tick Microbiome: Insights into Midgut and Salivary Gland Microbiota of Female Ixodes ricinus Ticks

The ectoparasite Ixodes ricinus is an important vector for many tick-borne diseases (TBD) in the northern hemisphere, such as Lyme borreliosis, rickettsiosis, human granulocytic anaplasmosis, or tick-borne encephalitis virus. As climate change will lead to rising temperatures in the next years, we expect an increase in tick activity, tick population, and thus in the spread of TBD. Consequently, it has never been more critical to understand relationships within the microbial communities in ticks that might contribute to the tick's fitness and the occurrence of TBD. Therefore, we analyzed the microbiota in different tick tissues such as midgut, salivary glands, and residual tick material, as well as the microbiota in complete Ixodes ricinus ticks using 16S rRNA gene amplicon sequencing. By using a newly developed DNA extraction protocol for tick tissue samples and a self-designed mock community, we were able to detect endosymbionts and pathogens that have been described in the literature previously. Further, this study displayed the usefulness of including a mock community during bioinformatic analysis to identify essential bacteria within the tick.

Emerging tick-borne spotted fever group rickettsioses in the Balkans

The impact of tick-borne pathogens (TBPs) on human health has increased in the last decades, since the incidence of emerging and re-emerging infectious and zoonotic tick-borne diseases has increased worldwide. Tick-borne rickettsiae of the Spotted Fever group (SFGR) are considered as emerging pathogens that can infect humans and cause a variety of non-specific clinical symptoms. Here, we report nine cases of atypical tick-borne diseases (9/460; 1.95%) that occurred over a period of four months (from 15 April 2021 to 16 August 2021) in Serbia, from which five cases were classified as confirmed SFGR infection, two cases as probable SFGR infection and two cases as suspected SFGR infection. Within cases of confirmed SFGR infection, R. helvetica was detected as the causative agent in two cases. The most common clinical finding was non-expanding persistent circular redness, followed by eschar and enlargement of regional lymph nodes, and pain at lesion site. Rickettsia outer membrane protein B (ompB) and citrate synthase (gltA) gene fragments were amplified from clinical samples and ticks attached to patients and IgG reacting with Rickettsia conorii antigen were detected in sera samples of patients, which are highly suggestive of exposure to SFGR. Surveillance and monitoring of rickettsial diseases in Serbia should continue and extended to new areas due to the increasing trend of clinical infections caused by SFGR in the country.

Tick-Borne Rickettsioses in the Iberian Peninsula

Tick-borne rickettsioses (TBR) are caused by obligate, intracellular bacteria of the spotted-fever group (SFG) of the genus Rickettsia (Order Rickettsiales), transmitted by hard ticks. TBR are one of the oldest known vector-borne zoonoses and pose a threat to both human and animal health, as over the years, new SFG Rickettsia spp. have been reported worldwide with the potential to be human pathogens. In Portugal and Spain, the countries that constitute the Iberian Peninsula, reported TB rickettsiae causing human disease include Rickettsia conorii conorii, Rickettsia conorii israelensis, Rickettsia slovaca, Rickettsia raoultii, Candidatus Rickettsia rioja, Rickettsia sibirica mongolitimonae, and Rickettsia monacensis. An allochthonous case of TBR caused by Rickettsia massiliae, described in Spain, points to the need to monitor disease epidemiology, to predict risks of exposure and spread of disease, and taking into account globalization and climate changes. This review aims to provide up-to-date information on the status of TBR in the Iberian Peninsula, as well as to show the importance of a national and international collaborative epidemiology surveillance network, towards monitoring Rickettsia spp. circulation in both Portugal and Spain.

What do we know about the microbiome of I. ricinus?

I. ricinus is an obligate hematophagous parasitic arthropod that is responsible for the transmission of a wide range of zoonotic pathogens including spirochetes of the genus Borrelia, Rickettsia spp., C. burnetii, Anaplasma phagocytophilum and Francisella tularensis, which are part the tick´s microbiome. Most of the studies focus on "pathogens" and only very few elucidate the role of "non-pathogenic" symbiotic microorganisms in I. ricinus. While most of the members of the microbiome are leading an intracellular lifestyle, they are able to complement tick´s nutrition and stress response having a great impact on tick´s survival and transmission of pathogens. The composition of the tick´s microbiome is not consistent and can be tied to the environment, tick species, developmental stage, or specific organ or tissue. Ovarian tissue harbors a stable microbiome consisting mainly but not exclusively of endosymbiotic bacteria, while the microbiome of the digestive system is rather unstable, and together with salivary glands, is mostly comprised of pathogens. The most prevalent endosymbionts found in ticks are Rickettsia spp., Ricketsiella spp., Coxiella-like and Francisella-like endosymbionts, Spiroplasma spp. and Candidatus Midichloria spp. Since microorganisms can modify ticks' behavior, such as mobility, feeding or saliva production, which results in increased survival rates, we aimed to elucidate the potential, tight relationship, and interaction between bacteria of the I. ricinus microbiome. Here we show that endosymbionts including Coxiella-like spp., can provide I. ricinus with different types of vitamin B (B2, B6, B7, B9) essential for eukaryotic organisms. Furthermore, we hypothesize that survival of Wolbachia spp., or the bacterial pathogen A. phagocytophilum can be supported by the tick itself since coinfection with symbiotic Spiroplasma ixodetis provides I. ricinus with complete metabolic pathway of folate biosynthesis necessary for DNA synthesis and cell division. Manipulation of tick´s endosymbiotic microbiome could present a perspective way of I. ricinus control and regulation of spread of emerging bacterial pathogens.

The diversity and evolutionary relationships of ticks and tick-borne bacteria collected in China

Background

Ticks (order Ixodida) are ectoparasites, vectors and reservoirs of many infectious agents affecting humans and domestic animals. However, the lack of information on tick genomic diversity leaves significant gaps in the understanding of the evolution of ticks and associated bacteria.

Results

We collected > 20,000 contemporary and historical (up to 60 years of preservation) tick samples representing a wide range of tick biodiversity across diverse geographic regions in China. Metagenomic sequencing was performed on individual ticks to obtain the complete or near-complete mitochondrial (mt) genome sequences from 46 tick species, among which mitochondrial genomes of 23 species were recovered for the first time. These new mt genomes data greatly expanded the diversity of many tick groups and revealed five cryptic species. Utilizing the same metagenomic sequence data we identified divergent and abundant bacteria in Haemaphysalis, Ixodes, Dermacentor and Carios ticks, including nine species of pathogenetic bacteria and potentially new species within the genus Borrelia. We also used these data to explore the evolutionary relationship between ticks and their associated bacteria, revealing a pattern of long-term co-divergence relationship between ticks and Rickettsia and Coxiella bacteria.

Conclusions

In sum, our study provides important new information on the genetic diversity of ticks based on an analysis of mitochondrial DNA as well as on the prevalence of tick-borne pathogens in China. It also sheds new light on the long-term evolutionary and ecological relationships between ticks and their associated bacteria.

Graphical Abstract

Supplementary Information

The online version contains supplementary material available at 10.1186/s13071-022-05485-3.

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.

Spotted Fever Group Rickettsia spp. Diversity in Ticks and the First Report of Rickettsia hoogstraalii in Romania

Simple Summary

Ticks are important parasites that feed on the blood of various host species, representing the most important arthropods transmitting diseases in Europe. Continuous changes in both tick distribution and abundance are related to multiple factors, including climate change. These changes have strong implications for both animal and human health; therefore, continuous surveillance of tickborne diseases is required for an appropriate evaluation of the potential risks faced by animals and humans in a given area. The spotted fever group Rickettsia comprises a large number of zoonotic agents with an increasing importance recognized in the last 30 years. The aim of this study was to evaluate these bacteria in ticks in Romania. Five Rickettsia species were identified in different tick species, with new pathogen–tick associations reported. Rickettsia hoogstraalii, one member of this group, was detected for the first time in Romania and in Rhipicephalus rossicus ticks. This species was first described in 2006 in Croatia, and its pathogenicity is not well known. In addition, the detection of R. raoultii and R. monacensis in unfed larvae of Haemaphysalis punctata reinforce the hypothesis of transmission of Rickettsia from female ticks to larvae; therefore the bite of larvae could pose a health risk.

Abstract

Tickborne bacterial pathogens have been described worldwide as risk factors for both animal and human health. Spotted fevers caused by Rickettsiae may cause non-specific symptoms, which make clinical diagnosis difficult. The aim of the current study was to evaluate and review the diversity of SFG Rickettsiae in ticks collected in 41 counties in Romania. A total of 2028 questing and engorged ticks collected in Romania belonging to five species were tested by PCR amplification of Rickettsia spp. gltA and 17-D gene fragments: Ixodes ricinus (n = 1128), Dermacentor marginatus (n = 507), D. reticulatus (n = 165), Rhipicephalus rossicus (n = 128) and Haemaphysalis punctata (n = 100). Five Rickettsia species were identified following DNA sequence analysis: R. helvetica, R. monacensis, R. slovaca, R. raoultii, and R. hoogstraalii. The most common species detected was R. monacensis. Moreover, R. hoogstraalii was detected for the first time in Romania and in R. rossicus ticks. The detection of R. raoultii and R. monacensis in questing larvae of Hae. punctata suggests the possible transovarial transmission of these Rickettsia species in ticks. The detection of R. hoogstraalii for the first time in Romania increases the reported SFG Rickettsia diversity in the country.

Prevalence of Bacterial and Protozoan Pathogens in Ticks Collected from Birds in the Republic of Moldova

Epidemiological knowledge on pathogens in ticks feeding on birds in Moldova is scarce. To reduce this gap of information, a total of 640 migrating and native birds of 40 species were caught from 2012 to 2015 and examined for the presence of ticks in the Republic of Moldova. Altogether, 262 ticks belonging to five tick species (Ixodes ricunus n = 245, Ixodes frontalis n = 12, Haemaphysalis punctata n = 2, Hyalomma marginatum n = 2 (only males), Dermacentor marginatus n = 1) were collected from 93 birds. Of these ticks, 250 (96%) were at the stage of a nymph and 9 at the stage of a larva (3%). One imago of I. frontalis and two imagoes of Hy. marginatum were found. Generally, ticks infested 14.1% of the assessed birds belonging to 12 species. DNA was extracted from individual ticks with subsequent PCR targeting Rickettsia spp., Borrelia spp. in general, as well as relapsing fever-associated Borrelia spp., in particular, Anaplasma phagocytophilum, Neoehrlichia mikurensis, Babesia spp. and Coxiella burnetii. The bird species Turdus merula showed the heaviest infestation with ticks and the highest incidence of infected ticks. Altogether, 32.8% of the assessed ticks (n = 86) were positive for one of the pathogens. DNA of Borrelia spp. was found in 15.2% (40/262) of the investigated ticks; in 7.6% of ticks (20/262), DNA of rickettsiae was detected; 6.9% (18/262) of the ticks were positive for A. phagocytophilum DNA; in 1.5% of the ticks (4/262), DNA of Neoehrlichia mikurensis was detected, followed by 1.5% (4/262) Babesia microti and 1.5% (4/262) Borrelia miyamotoi. Within the B. burgdorferi complex, B. garinii (n = 36) was largely predominant, followed by B. valaisiana (n = 2) and B. lusitaniae (n = 2). Among the detected Rickettsia spp., R. monacensis (n = 16), R. helvetica (n = 2) and R. slovaca (n = 1) were identified. In conclusion, the study provided some new information on the prevalence of ticks on birds in Moldova, as well as the presence of DNA of pathogens in the ticks. By doing so, it provided an additional piece in the puzzle of the global epidemiology of tick-transmitted infectious diseases from a geographic side from where respective surveillance data are scarce.

Utility of ultra-rapid real-time PCR for detection and prevalence of Rickettsia spp. in ticks

Background

Rickettsia spp. are important tick-borne pathogens that cause various human and animal diseases worldwide. A tool for rapid and accurate detection of the pathogens from its vectors is necessary for prevention of Rickettsioses propagation in humans and animals, which are infested by ticks. Therefore, this study was conducted to evaluate a molecular tool, ultra-rapid real-time PCR (UR-qPCR), for rapid and accurate detection of Rickettsia spp. from 5644 ticks in 408 pools collected from livestock and their surrounding environments in Gangwon and Jeju province in South Korea.

Results

The UR-qPCR of Rickettsia DNA showed a limit of detection of 2.72 × 10¹ copies of Rickettsia DNA and no cross reaction with other tick-borne pathogens, namely Anaplasma phagocytophilum, Ehrlichia chaffeensis, E. canis, Toxoplasma gondii, and Borrelia burgdorferi. In addition, the PCR assay also showed possibility of various Rickettsia species detection including R. monacensis, “Candidatus R. longicornii”, R. japonica, R. roultii, and R. tamurae. The collected ticks were identified with major species belonged to Haemaphysalis longicornis (81.62%), followed by H. flava (15.19%), and Ixodes nipponensis (3.19%). Rickettsia detection from tick samples using the UR-qPCR showed that the minimum infection rate (MIR) of Rickettsia in collected ticks was 1.24‰ and that all positive pools contained H. longicornis, equal to the MIR of 1.39‰ of this species. Additionally, MIR of Rickettsia spp. detected in ticks collected in Gangwon and Jeju was 1.53‰ and 0.84‰, respectively. Furthermore, the sequencing results of the 17 kDa protein antigen gene and ompA gene showed that Rickettsia spp. sequences from all pools were related to “Candidatus R. longicornii” and “Candidatus R. jingxinensis”.

Conclusions

The UR-qPCR system was demonstrated to be useful tool for accurate and rapid detection of Rickettsia from its vector, ixodid ticks, within 20 min. The data on Rickettsia spp. in ticks detected in this study provide useful information on the distribution of Rickettsia in previously unstudied Korean provinces, which are important for the prevention and control of the spread of rickettsioses in both animals and humans in the country.

Epidemiological, Clinical, and Microbiological Characteristics in a Large Series of Patients Affected by Dermacentor-Borne-Necrosis-Erythema-Lymphadenopathy from a Unique Centre from Spain

During recent decades, a tick-borne rickettsial syndrome, characterized by eschar and painful lymphadenopathy after Dermacentor marginatus-bite, has been described as an emerging rickettsiosis in Europe. Our group named it DEBONEL (Dermacentor-borne-necrosis-erythema-lymphadenopathy), regarding the vector and the main infection signs. Other groups called it TIBOLA (tick-borne-lymphadenophathy) and, later, SENLAT (scalp-eschar-and-neck-lymphadenopathy-after-tick-bite), expanding, in the latter, the etiological spectrum to other pathogens. Objective: To investigate the etiology of DEBONEL agents in our area, and to compare their epidemiological/clinical/microbiological characteristics. During 2001-2020, 216 patients clinically diagnosed of DEBONEL (the largest series from one center) in La Rioja (northern Spain) were examined. Rickettsia spp. were amplified in 14/104 (13.46%) blood samples, 69/142 (48.59%) eschar swabs, 7/7 (100%) biopsies, and 71/71 (100%) D. marginatus from patients. For samples in which Rickettsia was undetected, no other microorganisms were found. 'Candidatus Rickettsia rioja', Rickettsia slovaca, Rickettsia raoultii, and Rickettsia DmS1 genotype were detected in 91, 66, 4, and 3 patients, respectively. DEBONEL should be considered in patients with clinical manifestations herein described in areas associated to Dermacentor. The most frequently involved agent in our environment is 'Ca. R. rioja'. The finding of Rickettsia sp. DmS1 in ticks attached to DEBONEL patients suggests the implication of other rickettsia genotypes.

High Prevalence of Tick-Borne Zoonotic Rickettsia slovaca in Ticks from Wild Boars, Northeastern Italy

Simple Summary

Tick-borne rickettsioses are emerging diseases that have become widespread in many European countries, particularly in those facing the Mediterranean basin. Although Rickettsia conorii was traditionally thought to be the most threatening species, in recent decades, thanks to the improvements in biomolecular tools, other zoonotic species have been identified, such as Rickettsia slovaca, the etiological agent of scalp eschar and neck lymphadenopathy after tick bite (SENLAT), as well as other neglected species. These pathogens are present in Italy, but few data are available. This research aimed to improve the epidemiological knowledge of rickettsial infections in tick and wild boar populations in the Euganean Hills Regional Park, an enclosed area in northeastern Italy. Both tick and wild boar blood samples were tested using biomolecular methods to detect and identify Rickettsia species. Only ticks tested positive, and Rickettsia slovaca was the most frequently detected species, showing a high prevalence, followed by Rickettsia monacensis and Rickettsia helvetica. These data highlight a non-negligible presence of these pathogens in northern Italy and outline that rickettsial infections deserve further investigation.

Abstract

Tick-borne rickettsiae are emerging pathogens that are becoming widespread in Europe. Rickettsiae are endemic in Italy, but epidemiological data are currently scarce. This study aimed to improve our knowledge about rickettsial infections in tick and wild boar populations. Blood and ticks were collected from 102 wild boars in 2010 and 2018. Ticks were also collected from the vegetation in the area. All of the samples were examined using real-time PCR targeting the gltA gene to detect Rickettsia DNA. Positivity was confirmed by PCR amplifying the gltA and/or ompB genes. A total of 254 ticks and 89 blood samples were analyzed. Zoonotic rickettsiae were detected in the ticks but not in the blood samples. Rickettsia slovaca (R. slovaca) was the most prevalent in ticks and was found in 23.7% of Dermacentor marginatus (D. marginatus) and in 3.4% of Ixodes ricinus (I. ricinus). Other zoonotic species were identified, such as Rickettsia monacensis, which was detected in 12% of I. ricinus ticks, and Rickettsia helvetica which was found in 3.4% of questing I. ricinus ticks and in 1.1% of D. marginatus collected from wild boars. This study highlights a high prevalence of zoonotic rickettsiae, particularly that of R. slovaca, in northeastern Italy. As rickettsioses are underreported and underdiagnosed in human medicine, both clinicians and researchers should pay more attention to this topic.

Prevalence of causative agents of transmissive tick-borned ricketsious in the Crimean peninsula

The paper presents the results of a study of the prevalence of Ixodid ticks - potential carriers of tick-borne rickettsiosis pathogens. Ectoparasites were collected in various natural and climatic zones of the Crimean Peninsula within the year 2016-2018. As a result of screening with the help of real-time PCR analysis (PCR-RT), a genetic marker (a section of the gltA gene) of the rickettsia group of tick-borne spotted fever was detected in ticks. The most common DNA marker of rickettsia was found in ticks in the eastern regions of the steppe zone - 50,6 %, in the north-western part of the steppe zone this value was 12,0 %. The least amount of rickettsia target DNA was detected in ticks collected in the mountain forest and south bank zones - 4,5 %. As a result of sequencing of positive DNA samples from fragments of the gltA, ompA, ompB, and sca4 genes, the species composition of rickettsias was established. The DNA of 8 species of rickettsia was identified: Circulation of three R. conorii, R. massiliae, R. sibirica subsp. mongolotimonae, R. slovaca, R. aeschlimannii, R. monacensis, R. helvetica, R. raoultii. R. massiliae, R. slovaca, and R. helvetica were established in the Crimean Peninsula for the first time. The peculiarities of the geographical distribution of the identified rickettsia species were determined, which was due to the spread of mites-carriers of pathogens. The revealed diversity of rickettsia species and their vectors, due to the isolation of the areas of the main feeding animals and the established routes of migratory birds, suggests the circulation of other rickettsia species on the territory of the Crimean Peninsula. The obtained results suggest that the diseases of tick-borne rickettsiosis in the Crimean Peninsula can be caused not only by R. conorii, as previously thought, but also by other types of rickettsii.

Causes of fever in returning travelers: a European multicenter prospective cohort study

BACKGROUND

Etiological diagnosis of febrile illnesses in returning travelers is a great challenge, particularly when presenting with no focal symptoms [acute undifferentiated febrile illnesses (AUFI)], but is crucial to guide clinical decisions and public health policies. In this study, we describe the frequencies and predictors of the main causes of fever in travelers.

METHODS

Prospective European multicenter cohort study of febrile international travelers (November 2017-November 2019). A predefined diagnostic algorithm was used ensuring a systematic evaluation of all participants. After ruling out malaria, PCRs and serologies for dengue, chikungunya and Zika viruses were performed in all patients presenting with AUFI ≤ 14 days after return. Clinical suspicion guided further microbiological investigations.

RESULTS

Among 765 enrolled participants, 310/765 (40.5%) had a clear source of infection (mainly traveler's diarrhea or respiratory infections), and 455/765 (59.5%) were categorized as AUFI. AUFI presented longer duration of fever (p < 0.001), higher hospitalization (p < 0.001) and ICU admission rates (p < 0.001). Among travelers with AUFI, 132/455 (29.0%) had viral infections, including 108 arboviruses, 96/455 (21.1%) malaria and 82/455 (18.0%) bacterial infections. The majority of arboviral cases (80/108, 74.1%) was diagnosed between May and November. Dengue was the most frequent arbovirosis (92/108, 85.2%). After 1 month of follow-up, 136/455 (29.9%) patients with AUFI remained undiagnosed using standard diagnostic methods. No relevant differences in laboratory presentation were observed between undiagnosed and bacterial AUFI.

CONCLUSIONS

Over 40% of returning travelers with AUFI were diagnosed with malaria or dengue, infections that can be easily diagnosed by rapid diagnostic tests. Arboviruses were the most common cause of AUFI (above malaria) and most cases were diagnosed during Aedes spp. high season. This is particularly relevant for those areas at risk of introduction of these pathogens. Empirical antibiotic regimens including doxycycline or azithromycin should be considered in patients with AUFI, after ruling out malaria and arboviruses.

Prevalence of tick infestation and molecular characterization of spotted fever Rickettsia massiliae in Rhipicephalus species parasitizing domestic small ruminants in north-central Nigeria

Ticks are of great menace to animal and human health. They serve as vectors to both animals and human pathogens including Rickettsia species. Tick-borne rickettsiosis in West Africa remains incompletely understood. We determined the prevalence of tick infestation among small ruminants and molecularly described a clinically significant spotted fever Rickettsia massiliae from Rhipicephalus ticks collected from North-Central, Nigeria. A total of 352 small ruminants comprising of 152 sheep and 200 goats that were brought for slaughter at the major small ruminant slaughterhouse in Ilorin were examined for the presence of ticks. The collected Rhipicephalus species were subjected to molecular studies to detect and characterize Rickettsia massiliae. Of the small ruminants examined, 21 sheep and 46 goats were infested with ticks representing 13.82% and 23.00% respectively. Eight and nine different species of ticks were detected in sheep and goats respectively, with Rhipicephalus (Boophilus) decoloratus being the most prevalent tick species in both sheep and goats. There was a significant difference (p <0.01) in the prevalence of the different tick species collected in sheep and in goats. Based on the PCR amplification of the 23S-5S intergenic spacer (IGS), only 2 of the 142 Rhipicephalus tick samples screened for R. massiliae were positive (1.41%; 95% CI = 0.39-4.99). Rickettsia massiliae was detected from Rhipicephalus turanicus collected from sheep. Sequences obtained from the PCR carried out by amplifying Rickettsia 23S-5S IGS showed 99-100% close identity with members of the R. massiliae group. This study has for the first time confirmed the presence of spotted fever group Rickettsia massiliae from feeding ticks in Nigerian small ruminants. Further investigations to determine the possible pathogenic role of human R. massiliae infection in Nigeria would be beneficial.

Molecular Characterization and Gene Expression Analysis of Aquaporin in Haemaphysalis qinghaiensis

Aquaporins (AQPs) are important functional proteins and are widely present in the cell membrane of almost all organisms, mediating transmembrane transport of liquid and other solutes. Much is known about the molecular characterization of AQPs in other tick species; however, nothing is known about them in Haemaphysalis qinghaiensis. In this study, we first sequenced the transcript variants of AQPs in H. qinghaiensis (HqAQPs), analyzed the biological structure features of AQPs, and investigated the pattern of gene expression of the AQP gene of H. qinghaiensis in different tick tissues and stages to predict their biological functions. In conclusion, four AQP transcript variants (i.e., HqAQP1-1, HqAQP1-2, HqAQP1-3, and HqAQP1-4) of H. qinghaiensis were found, and the sequences were comparable with its orthologs from the reported tick species. Gene expression of AQPs in different tick tissues and stages showed the higher expression level in salivary glands and gut of adult female, as well as in the female and nymph than in Malpighian tubules, ovary, male, larvae, and egg. Further studies will be performed to evaluate the function of HqAQPs against H. qinghaiensis infestation on animals.

The Ixodes scapularis Symbiont Rickettsia buchneri Inhibits Growth of Pathogenic Rickettsiaceae in Tick Cells: Implications for Vector Competence

Ixodes scapularis is the primary vector of tick-borne pathogens in North America but notably does not transmit pathogenic Rickettsia species. This tick harbors the transovarially transmitted endosymbiont Rickettsia buchneri, which is widespread in I. scapularis populations, suggesting that it confers a selective advantage for tick survival such as providing essential nutrients. The R. buchneri genome includes genes with similarity to those involved in antibiotic synthesis. There are two gene clusters not found in other Rickettsiaceae, raising the possibility that these may be involved in excluding pathogenic bacteria from the tick. This study explored whether the R. buchneri antibiotic genes might exert antibiotic effects on pathogens associated with I. scapularis. Markedly reduced infectivity and replication of the tick-borne pathogens Anaplasma phagocytophilum, R. monacensis, and R. parkeri were observed in IRE11 tick cells hosting R. buchneri. Using a fluorescent plate reader assay to follow infection dynamics revealed that the presence of R. buchneri in tick cells, even at low infection rates, inhibited the growth of R. parkeri by 86-100% relative to R. buchneri-free cells. In contrast, presence of the low-pathogenic species R. amblyommatis or the endosymbiont R. peacockii only partially reduced the infection and replication of R. parkeri. Addition of host-cell free R. buchneri, cell lysate of R. buchneri-infected IRE11, or supernatant from R. buchneri-infected IRE11 cultures had no effect on R. parkeri infection and replication in IRE11, nor did these treatments show any antibiotic effect against non-obligate intracellular bacteria E. coli and S. aureus. However, lysate from R. buchneri-infected IRE11 challenged with R. parkeri showed some inhibitory effect on R. parkeri infection of treated IRE11, suggesting that challenge by pathogenic rickettsiae may induce the antibiotic effect of R. buchneri. This research suggests a potential role of the endosymbiont in preventing other rickettsiae from colonizing I. scapularis and/or being transmitted transovarially. The confirmation that the observed inhibition is linked to R. buchneri's antibiotic clusters requires further investigation but could have important implications for our understanding of rickettsial competition and vector competence of I. scapularis for rickettsiae.

Potential Role of Avian Populations in the Epidemiology of Rickettsia spp. and Babesia spp

Birds often are carriers of hard and/or soft ticks harboring pathogens of humans and veterinary concern. Migratory avian species, which cover long distance by their flight, may deeply influence the ticks’ distribution worldwide; in particular, they can introduce in a given geographic area new tick species and related tick-borne pathogens. Studies about the detection of tick-borne agents in birds are not numerous, whereas more attention has been turned to the presence of these microorganisms in ticks carried by birds. The present review focused on the role of avian populations in the epidemiology of rickettsioses and babesioses, which represent two severe problems for the health of humans and other mammals.

Canine and Feline Parasitology: Analogies, Differences, and Relevance for Human Health

Cats and dogs are treated as family members by most pet owners. Therefore, a high quality of veterinary care and preventive medicine is imperative for animal health and welfare and for the protection of humans from zoonotic pathogens. There is a general perception of cats being treated as "small dogs," especially in the field of clinical parasitology. As a result, several important differences between the two animal species are not taken into proper consideration and are often overlooked. Dogs and cats are profoundly different under evolutionary, biological, ethological, behavioral, and immunological standpoints. These differences impact clinical features, diagnosis, and control of canine and feline parasites and transmission risk for humans. This review outlines the most common parasitoses and vector-borne diseases of dogs and cats, with a focus on major convergences and divergences, and discusses parasites that have (i) evolved based on different preys for dogs and cats, (ii) adapted due to different immunological or behavioral animal profiles, and (iii) developed more similarities than differences in canine and feline infections and associated diseases. Differences, similarities, and peculiarities of canine and feline parasitology are herein reviewed in three macrosections: (i) carnivorism, vegetarianism, anatomy, genetics, and parasites, (ii) evolutionary adaptation of nematodes, including veterinary reconsideration and zoonotic importance, and (iii) behavior and immune system driving ectoparasites and transmitted diseases. Emphasis is given to provide further steps toward a more accurate evaluation of canine and feline parasitology in a changing world in terms of public health relevance and One Health approach.

Identification of Rickettsia spp., Anaplasma spp., and an Ehrlichia canis-like agent in Rhipicephalus microplus from Southwest and South-Central China

Rhipicephalus microplus is considered to be the most important tick infesting cattle, buffalo, horse, goats as well as other animals. They transmit diseases between domestic animals and act as vectors of a variety of zoonotic pathogens. Although pathogens harbored by R. microplus have been extensively studied, the Rickettsiales pathogens vectored by R. microplus in some areas of China remained largely unexplored. From August to October 2020, a total of 291 R. microplus ticks were collected from goats and cattle in three Southern China provinces, Guangxi (n = 138), Sichuan (n = 120) and Hubei (n = 33) provinces. Phylogenetic analysis based on COI gene sequences shows that these ticks are divided into three distinct clades, indicating the remarkable genetic diversity of R. microplus ticks in China. These samples were subsequently screened for the presence of Rickettsia, Anaplasma and Ehrlichia using conventional PCR and sequencing. Subsequently, five bacterial species were identified. Out of the 120 tick DNA samples from Sichuan province, 35.83% (43/120) were positive for Rickettsia sp. belonging to spotted fever group (SFG), 12.50% (15/120) were positive for Anaplasma marginale and 0.83% (1/120) was identified as A. platys. From the 138 DNA samples from Guangxi province, an Ehrlichia canis-like and Rickettsia sp. were detected, with a positive rate of 11.59% (16/138) and 2.17% (3/138), respectively. A. capra DNA was detected in 4 out of 33 (12.12%) samples from Hubei province. Notably, the 16S, gltA and groEL sequences of the E. canis-like are closely related to the E. canis strain previously identified from China, and form a distinct cluster in the phylogenetic trees. Collectively, our results expand the knowledge on tick-borne Rickettsiales pathogens in China. Because the state of engorgement of ticks was not recorded, it is not clear at this stage whether these pathogens are infecting the ticks or are simply present in the blood meal. Given the public health significance of SFG Rickettsia, A. capra, A. platys and E. canis, a thorough investigation of the diversity and presence of pathogens in R. microplus in areas with tick-associated diseases are needed.

Molecular identification of zoonotic Rickettsia species in Ixodidae parasitizing wild lagomorphs from Mediterranean ecosystems

A survey study was carried out to identify tick species parasitizing wild lagomorphs in Mediterranean ecosystems in southern Spain and to determine the occurrence of Rickettsia species present in these ticks in this region. A total of 1304 European wild rabbits (Oryctolagus cuniculus) and 58 Iberian hares (Lepus granatensis) were individually examined for the presence of ticks. Ticks were found in 42.9% and 50% of the wild rabbits and hares sampled, respectively. A total of 1122 ticks were collected and five species, including Rhipicephalus pusillus, Hyalomma lusitanicum, Haemaphysalis hispanica, Ixodes ventalloi and Rhipicephalus sanguineus sensu lato (s.l.), were microscopically and molecularly identified at the 16S rRNA gene. This is the first study on Ixodidae parasitizing Iberian hares. The presence of Rickettsia DNA was assessed in 254 tick pools (according to hunting states, lagomorph species, tick species and tick development stage) using PCR assays targeting the rOmpA, rOmpB and gltA. Twenty-seven pools (10.6%) were positive to Rickettsia DNA. Five zoonotic Rickettsia species were identified, being Rickettsia massiliae the most frequent (4.7%), followed by Rickettsia sibirica subsp. mongolitimonae (2.8%), Rickettsia slovaca (2.0%), Rickettsia aeschlimannii (0.8%) and Rickettsia africae (0.4%). The results suggest that wild rabbits and Iberian hares are parasitized by a wide range of tick species and that these lagomorphs may play an important role in the sylvatic cycle of some zoonotic Rickettsia species in Mediterranean ecosystems. Our data represent the first report of R. massiliae, R. aeschlimannii, R. slovaca and R africae in ticks collected in wild lagomorphs in Europe, and the first report of not imported R. africae in this continent. Since R. slovaca and R. africae DNA was detected in tick species different to their main vectors, further studies are warranted to unravel the role of wild lagomorphs in the epidemiology of these vector-borne pathogens.