High Diversity, Prevalence, and Co-infection Rates of Tick-Borne Pathogens in Ticks and Wildlife Hosts in an Urban Area in Romania

Ticking Down Sodium Levels-An Atypical Link Between Chronic Hyponatremia and Borreliosis

Lyme disease (LD), caused by the spirochete Borrelia burgdorferi, is the most prevalent tick-borne disease in Europe, including Romania, where endemic areas are well documented. It has a wide range of clinical manifestations and severity, including rare neurological complications. Persistent hyponatremia is an atypical presentation of Lyme neuroborreliosis and can be associated with the syndrome of inappropriate antidiuretic hormone secretion (SIADH). SIADH is characterized by unregulated antidiuretic hormone release, leading to impaired water excretion, dilutional hyponatremia, and low serum osmolality. We report the case of a 16-year-old female with clinically well-tolerated, but severe, refractory hyponatremia, who was poorly responsive to intravenous sodium supplementation and fluid management. Complex investigations ruled out multiple causes of hyponatremia; neuroborreliosis was confirmed via positive Borrelia serologies, despite the absence of a suggestive history of exposure. SIADH likely symptomatology resulted from central nervous system inflammation induced by Borrelia, a mechanism rarely documented in the medical literature. Treatment with antibiotics and fluid restriction led to a gradual improvement in fluid balance and sodium homeostasis. This case emphasizes the importance of considering rare infectious causes, such as LD, in patients with unexplained SIADH, especially in endemic areas. It highlights the importance of a multidisciplinary approach in intricate, complex cases.

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).

Guild Dynamics and Pathogen Interactions in Hyalomma Ticks From Algerian Cattle

Ticks are pivotal in transmitting a variety of pathogens that affect both humans and animals. These pathogens often occur in guilds, groups of species that exploit similar resources in similar ways. Although the composition of tick-borne pathogen (TBP) guilds is well-documented, the interactions among pathogens within these guilds remain poorly understood. We hypothesized that abiotic and biotic factors significantly influence the patterns of occurrence and interactions among pathogens within these guilds. To investigate this, we analyzed microfluidic-based high-throughput data on microorganisms from 166 Hyalomma excavatum ticks (94 male and 72 female) collected across different seasons from cattle in the central Algerian steppe using network analysis to uncover complex pathogen-pathogen interaction patterns. We found that female ticks had a higher infection rate (63.9%) with common pathogens such as Rickettsia slovaca (26.4%), unclassified Apicomplexa (22.2%), and Borrelia afzelii (19.4%). Male ticks showed a 56.4% infection rate, with Rickettsia (31.1%) and R. slovaca (16%) being the most prevalent. Notable pathogen-pathogen interactions within guilds were identified, with positive associations such as between R. slovaca and Rickettsia conorii in males, and B. afzelii and Borrelia spielmanii in females, indicating cooperative interactions. Conversely, negative associations, such as between Anaplasma phagocytophilum and Francisella tularensis, suggested competitive exclusion. The observed variation in interaction patterns under different conditions indicates that ecological determinants, both biotic and abiotic, influence pathogen association dynamics within guilds. These findings have significant implications for understanding disease transmission and developing control strategies.

Ticks and Tick-Borne Pathogens in Popular Recreational Areas in Tallinn, Estonia: The Underestimated Risk of Tick-Borne Diseases

This study reveals a significant presence of ticks and tick-borne pathogens in urban recreational areas of Tallinn, Estonia. During the period of May-June 2018, 815 Ixodes ticks were collected from an area of 11,200 m2 using the flagging method. Tick density reached up to 18.8 ticks per 100 m2, indicating a high concentration of ticks in these urban green spaces. Pathogen analysis demonstrated that 34% of the collected ticks were infected with at least one pathogen. Specifically, Borrelia burgdorferi s.l., the causative agent of Lyme borreliosis, was detected in 17.4% of the ticks; Rickettsia spp. was detected in 13.5%; Neoehrlichia mikurensis was detected in 5.5%; Borrelia miyamotoi was detected in 2.6%; and Anaplasma phagocytophilum and tick-borne encephalitis virus were detected in 0.5% each. These findings indicate that the prevalence and abundance of ticks and tick-borne pathogens in these urban environments are comparable to or even exceed those observed in natural endemic areas. Given the increasing incidence of Lyme borreliosis in Central and Northern Europe, the risk of tick bites and subsequent infection in urban recreational sites should not be underestimated. Public health measures, including enhanced awareness and precautionary information, are essential to mitigate the risk of tick-borne diseases in these urban settings.

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.

Anaplasma phagocytophilum in urban and peri-urban passerine birds in Ile-de-France

Wild animals in general, birds in particular, play a key role in transporting ticks and propagating tick-borne pathogens. Several studies have confirmed the infection of birds with Anaplasma phagocytophilum, with overall prevalence varying widely from country to country and/or study to study. This zoonotic bacterium, transmitted mainly by ticks of the genus Ixodes, is responsible for granulocytic anaplasmosis in humans (HGA) and domestic animals (cats, dogs, horses). The disease is also called tick-borne fever (TBF) in ruminants. Extremely rare in the USA, TBF is very common in Europe, where it causes economic losses in livestock. Conversely, HGA is well established in the USA whereas only a few less severe cases have been observed in Europe. Current typing techniques support the existence of multiple variants with differences in virulence/pathogenicity and tropism for certain tick and host species. However, epidemiological cycles remain difficult to characterize in Europe. Several studies describe a cycle apparently involving only birds in Europe, but no such study has been conducted in mainland France. Our objectives were to search for A. phagocytophilum in passerine birds in the Ile-de-France region and to explore their diversity using groEL and ankA gene typing and multilocus sequence typing (MLST). Various tissues (spleen, liver, and skin) were collected from cadavers of 680 passerines between March and December 2021. The presence of A. phagocytophilum was detected by qPCR Taqman targeting the msp2 gene. Three blackbirds (Turdus merula) were found positive, representing detection rates of 0.4 % in all birds tested and 3.3 % in blackbirds. The higher frequency of detection in blackbirds could be at least partially explained by their lifestyle, as they feed on the ground. Analysis of the results of groEL and ankA typing and MLST from positive blackbirds support the hypothesis that the avian A. phagocytophilum strains in Ile-de-France are distinct from those found in mammals, and that they form their own cluster in Europe.

Equine Granulocytic Anaplasmosis: A Systematic Review and Meta-Analysis on Clinico-Pathological Findings, Diagnosis, and Therapeutic Management

Equine granulocytic anaplasmosis (EGA) is a tick-borne disease affecting horses worldwide, caused by Anaplasma phagocytophilum. The disease ranges from non-specific clinical signs to fatal outcomes. This paper aimed to analyze EGA cases reported in peer-reviewed journals, particularly on clinico-pathological findings, diagnosis, and therapeutic management. Overall, 189 clinical cases from 31 publications were included in the study. Extensive symptomatology for the EGA cases was reported, of which mostly was fever (90.30%), followed by limb edema (48.51%), anorexia (41.79%), depression (32.84%), icterus (22.39%), ataxia (17.91), tachycardia (16.42%), and lethargy (15.67%). Laboratory tests revealed thrombocytopenia (90.32%), anemia (75%), decreased hematocrit (70.59%), leukopenia (55.88%), lymphopenia (58.14%), and neutropenia (41.67%) as the most common hematological abnormalities. For a subset of tested animals, hyperbilirubinemia (20/29), hyperfibrinogenemia (13/15), and hyponatremia (10/10) were also reported. The diagnosis was established by microscopic identification of morulae (in 153 cases), and/or PCR (120 cases), isolation (1 case), or serology (56 cases). For treatment, oxytetracycline was used in the majority (52.24%) of EGA cases, but recovery without antibiotherapy (10.34%) was also noted. In conclusion, the variety of clinical and pathological findings and the challenging therapeutic approaches reported suggest that EGA should be included in the differential diagnosis when fever occurs.

Using Potential Years of Life Lost (PYLL) to Compare Premature Mortality between Romanian Counties to Confirmed COVID-19 Cases in 2020 and 2021

This article examines the impact of the COVID-19 pandemic on potential years of life lost (PYLL) in Romania's counties in 2020 and 2021. PYLL highlights the burden of premature deaths in a community and is a useful tool for prioritizing community health issues. The study compares the PYLL variation between different counties, identifying disparities in premature mortality rates and highlighting areas that require specific public health interventions. The results indicate that COVID-19 has had a significant impact on potential years of life lost across the country. For the year 2020, the total number of deaths from confirmed COVID-19 cases was 19,455, of which 14,152 premature deaths caused 193,489 PYLL, with a crude rate of 1053.28 PYLL per 100,000 inhabitants. In 2021, there were 39,966 deaths from confirmed COVID-19 cases, with 28,777 premature deaths, 386,061 PYLL, and a crude rate of 2116.63 PYLL per 100,000 population. This study reveals significant variations only in some counties, based on BYLL rates, and in the two years analyzed. The proportion of premature deaths (<80 years) varied by county and gender. PYLL's analysis by gender shows that men experienced a higher number of premature deaths than women in most counties, and this trend persisted in both years. The results are presented in the form of thematic maps, highlighting standardized PYLL rates for both genders in each county, facilitating a visual understanding of regional disparities. The identified variations can serve as a basis for developing and implementing more effective public health policies, based on the specifics of each county.

Detection and genetic identification of Borrelia lusitaniae in questing Ixodes inopinatus tick from Tunisia

Background

Until now, there has been limited information on the prevalence and the phylogeny of Borrelia burgdorferi sensu lato in Ixodes ticks in Tunisia, particularly in Ixodes inopinatus.

Methods

The present study aimed to determine the prevalence and the phylogeny of B. burgdorferi s.l., in coexisted I. ricinus and I. inopinatus ticks collected from Northern Tunisia. One hundred questig ticks were collected during winter 2020 by tick-dragging method in Beja gouvernorate located in the north of Tunisia. Real-time PCR panel targeting B. burgdorferi s.l. 23S rRNA gene were performed. Positive DNA samples were subjected to conventional PCRs targeting 457 bp fragment of the Borrelia sp. flagellin (fla) gene using primers FlaF/FlaR. The identified Borrelia sp. isolate underwent partial sequence analysis to determine genospecies and evaluate their phylogenetic position.

Results

The study revealed a prevalence rate of 28% (28/100) for B. burgdorferi sensu lato in the Ixodes ticks. The prevalence rates across tick species and genders did not show significant variations (p > 0.05). Interestingly, the study underlines the coexistence of I. inopinatus and I. ricinus sharing the same geographic areas in Northern Tunisia. Furthermore, DNA of B. lusitaniae was detected in I. inopinatus ticks for the first time in Tunisia. Revealed B. lusitaniae bacterium is similar to previously identified strains in Mediterranean region, but distinct from those isolated exclusively from countries of Eastern and Central Europe, such as Serbia, Romania, and Poland. This study highlights the prevalence of B. burgdorferi s.l. in I. ricinus/I. inopinatus ticks, and reveals B. lusitaniae in I. inopinatus ticks for the first time in Tunisia.

Conclusion

These findings suggest the involvement of I. inopinatus as a potential vector of this pathogenic genospeciess in Tunisia. This may help understanding the ecology of Ixodes ticks, the natural infection and the transmission dynamics of Borrelia species in this country.

First report of Anaplasma spp., Ehrlichia spp., and Rickettsia spp. in Amblyomma gervaisi ticks infesting monitor lizards (Varanus begalensis) of Pakistan

Ticks pose significant health risks to both wildlife and humans due to their role as vectors for various pathogens. In this study, we investigated tick infestation patterns, tick-associated pathogens, and genetic relationships within the tick species Amblyomma gervaisi, focusing on its prevalence in monitor lizards (Varanus bengalensis) across different districts in Pakistan. We examined 85 monitor lizards and identified an overall mean intensity of 19.59 ticks per infested lizard and an overall mean abundance of 11.98 ticks per examined lizard. All collected ticks (n = 1019) were morphologically identified as A. gervaisi, including 387 males, 258 females, 353 nymphs, and 21 larvae. The highest tick prevalence was observed in the Buner district, followed by Torghar and Shangla, with the lowest prevalence in Chitral. Lizard captures primarily occurred from May to October, correlating with the period of higher tick infestations. Molecular analysis was conducted on tick DNA, revealing genetic similarities among A. gervaisi ticks based on 16S rDNA and ITS2 sequences. Notably, we found the absence of A. gervaisi ITS2 sequences in the NCBI GenBank, highlighting a gap in existing genetic data. Moreover, our study identified the presence of pathogenic microorganisms, including Ehrlichia sp., Candidatus Ehrlichia dumleri, Anaplasma sp., Francisella sp., Rickettsia sp., and Coxiella sp., in these ticks. BLAST analysis revealed significant similarities between these pathogenic sequences and known strains, emphasizing the potential role of these ticks as vectors for zoonotic diseases. Phylogenetic analyses based on nuclear ITS2 and mitochondrial 16S rDNA genes illustrated the genetic relationships of A. gervaisi ticks from Pakistan with other Amblyomma species, providing insights into their evolutionary history. These findings contribute to our understanding of tick infestation patterns, and tick-borne pathogens in monitor lizards, which has implications for wildlife health, zoonotic disease transmission, and future conservation efforts. Further research in this area is crucial for a comprehensive assessment of the risks associated with tick-borne diseases in both wildlife and humans.

Coinfection of Babesia and Borrelia in the Tick Ixodes ricinus-A Neglected Public Health Issue in Europe?

Ixodes ricinus nymphs and adults removed from humans, and larvae and nymphs from birds, have been analysed for infection with Babesia species and Borrelia species previously in separately published studies. Here, we use the same data set to explore the coinfection pattern of Babesia and Borrelia species in the ticks. We also provide an overview of the ecology and potential public health importance in Sweden of I. ricinus infected both with zoonotic Babesia and Borrelia species. Among 1952 nymphs and adult ticks removed from humans, 3.1% were PCR-positive for Babesia spp. Of these Babesia-positive ticks, 43% were simultaneously Borrelia-positive. Among 1046 immatures of I. ricinus removed from birds, 2.5% were Babesia-positive, of which 38% were coinfected with Borrelia species. This study shows that in I. ricinus infesting humans or birds in Sweden, potentially zoonotic Babesia protozoa sometimes co-occur with human-pathogenic Borrelia spp. Diagnostic tests for Babesia spp. infection are rarely performed in Europe, and the medical significance of this pathogen in Europe could be underestimated.

High-throughput screening of pathogens in Ixodes ricinus removed from hosts in Lombardy, northern Italy

Ticks are important vectors of many pathogens in Europe, where the most impactful species is Ixodes ricinus. Recently, the geographical distribution of this tick species has been expanding, resulting in an increased risk of human exposure to tick bites. With the present study, we aimed to screen 350 I. ricinus specimens collected from humans and wild animals (mainly ungulates), to have a broader understanding of the tick-borne pathogens circulating in the Lombardy region, in northern Italy. To do so, we took advantage of a high-throughput real-time microfluidic PCR approach to screen ticks in a cost-effective and time-saving manner. Molecular analysis of the dataset revealed the presence of four genera of bacteria and two genera of protozoa: in ungulates, 77 % of collected ticks carried Anaplasma phagocytophilum, while the most common pathogen species in ticks removed from humans were those belonging to Borrelia burgdorferi sensu lato group (7.6 %). We also detected other pathogenic microorganisms, such as Rickettisa monacensis, Rickettsia helvetica, Neoehrlichia mikurensis, Babesia venatorum, and Hepatozoon martis. Besides, we also reported the presence of the pathogenic agent Borrelia miyamotoi in the area (1.4 % overall). The most common dual co-infection detected in the same tick individual involved A. phagocytophilum and Rickettsia spp. Our study provided evidence of the circulation of different tick-borne pathogens in a densely populated region in Italy.

First report of spotted fever group Rickettsia aeschlimannii in Hyalomma turanicum, Haemaphysalis bispinosa, and Haemaphysalis montgomeryi infesting domestic animals: updates on the epidemiology of tick-borne Rickettsia aeschlimannii

Tick-borne Rickettsia spp. have long been known as causative agents for zoonotic diseases. We have previously characterized Rickettsia spp. in different ticks infesting a broad range of hosts in Pakistan; however, knowledge regarding Rickettsia aeschlimannii in Haemaphysalis and Hyalomma ticks is missing. This study aimed to obtain a better understanding about R. aeschlimannii in Pakistan and update the knowledge about its worldwide epidemiology. Among 369 examined domestic animals, 247 (66%) were infested by 872 ticks. Collected ticks were morphologically delineated into three genera, namely, Rhipicephalus, Hyalomma, and Haemaphysalis. Adult females were the most prevalent (number ₌ 376, 43.1%), followed by nymphs (303, 34.74%) and males (193, 22.13%). Overall, genomic DNA samples of 223 tick were isolated and screened for Rickettsia spp. by the amplification of rickettsial gltA, ompA, and ompB partial genes using conventional PCR. Rickettsial DNA was detected in 8 of 223 (3.58%) ticks including nymphs (5 of 122, 4.0%) and adult females (3 of 86, 3.48%). The rickettsial gltA, ompA, and ompB sequences were detected in Hyalomma turanicum (2 nymphs and 1 adult female), Haemaphysalis bispinosa (1 nymph and 1 adult female), and Haemaphysalis montgomeryi (2 nymphs and 1 adult female). These rickettsial sequences showed 99.71-100% identity with R. aeschlimannii and phylogenetically clustered with the same species. None of the tested Rhipicephalus microplus, Hyalomma isaaci, Hyalomma scupense, Rhipicephalus turanicus, Hyalomma anatolicum, Rhipicephalus haemaphysaloides, Rhipicephalus sanguineus, Haemaphysalis cornupunctata, and Haemaphysalis sulcata ticks were found positive for rickettsial DNA. Comprehensive surveillance studies should be adopted to update the knowledge regarding tick-borne zoonotic Rickettsia species, evaluate their risks to humans and livestock, and investigate the unexamined cases of illness after tick bite among livestock holders in the country.

History and Current Status of Mediterranean Spotted Fever (MSF) in the Crimean Peninsula and Neighboring Regions along the Black Sea Coast

Mediterranean spotted fever (MSF) is a tick-borne rickettsiosis caused by Rickettsia conorii subspecies conorii and transmitted to humans by Rhipicephalus sanguineus ticks. The disease was first discovered in Tunisia in 1910 and was subsequently reported from other Mediterranean countries. The first cases of MSF in the former Soviet Union were detected in 1936 on the Crimean Peninsula. This review summarizes the historic information and main features of MSF in that region and contemporary surveillance and control efforts for this rickettsiosis. Current data pertinent to the epidemiology of the disease, circulation of the ticks and distribution of animal hosts are discussed and compared for each of the countries in the Black Sea basin where MSF occurs.

Rickettsia species in Dermacentor reticulatus ticks feeding on human skin and clinical manifestations of tick-borne infections after tick bite

Dermacentor reticulatus ticks are sporadically removed from human skin and therefore the medical consequences of their feeding are neglected compared to Ixodes ricinus. We investigated the prevalence of pathogens in D. reticulatus removed from human skin and possible clinical manifestations suggestive of tick-borne diseases after a tick bite. A total of 2153 ticks were studied and of these only 34 were D. reticulatus. The mean prevalence of Rickettsia in D. reticulatus was 50.0% and R. raoultii was identified in 82.4% of infected D. reticulatus ticks. We confirmed the first case of R. aeschlimannii infection in D. reticulatus ticks. Among participants bitten by D. reticulatus, 13.3% reported reddening around the tick bite site and flu-like symptoms, including lymphadenopathy and 3.3% reported eschar on the tick site bite. All of the participants with flu-like symptoms after tick removal were bitten by ticks infected with R. raoultii. The results of this study indicate that even though D. reticulatus ticks bite humans sporadically, pathogenic Rickettsia have a remarkably high prevalence in this tick species. We can expect that the incidence of tick-borne lymphadenopathy might increase with the reported expansion of the D. reticulatus into new areas and its growing abundance in Central Europe.

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.

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

BACKGROUND

The availability of molecular techniques has significantly increased our understanding of bacteria of the order Rickettsiales, allowing the identification of distinct species in both vector and host arthropods. However, the literature lacks studies that comprehensively summarize the vast amount of knowledge generated on this topic in recent years. The purpose of this study was to conduct a comprehensive analysis of the distribution of Rickettsiales in arthropod vectors, animals and humans in the WHO European Region in order to provide useful information to predict the emergence of certain diseases in specific geographical areas and to formulate hypotheses regarding the possible pathogenetic role of some rickettsial species in the etiology of human pathological conditions.

METHODS

A systematic review of the literature in the PubMed and EMBASE databases was conducted following the PRISMA methodology using the search terms "Spotted fever" OR "rickettsiosis" OR "ricketts*" AND all the countries of the WHO European Region, from 1 January 2013 to 12 February 2022. Only studies that identified rickettsiae in human, animal or arthropod samples using molecular techniques were included in the review.

RESULTS

A total of 467 articles considering 61 different species of Rickettsiales with confirmed or suspected human pathogenicity were analyzed in the review. More than 566 identifications of Rickettsiales DNA in human samples were described, of which 89 cases were assessed as importation cases. A total of 55 species of ticks, 17 species of fleas, 10 species of mite and four species of lice were found infected. Twenty-three species of Rickettsiales were detected in wild and domestic animal samples.

CONCLUSION

The routine use of molecular methods to search for Rickettsiales DNA in questing ticks and other blood-sucking arthropods that commonly bite humans should be encouraged. Molecular methods specific for Rickettsiales should be used routinely in the diagnostics of fever of unknown origin and in all cases of human diseases secondary to an arthropod bite or animal contact.

Co-Infection of Potential Tick-Borne Pathogens of the Order Rickettsiales and Borrelia burgdorferi s. l. and Their Link to Season and Area in Germany

The prevalence of potential human pathogenic members of the order Rickettsiales differs between Borrelia burgdorferi sensu lato-positive and -negative tick microbiomes. Here, co-infection of members of the order Rickettsiales, such as Rickettsia spp., Anaplasma phagocytophilum, Wolbachia pipientis, and Neoehrlichia mikurensis as well as B. burgdorferi s.l. in the tick microbiome was addressed. This study used conventional PCRs to investigate the diversity and prevalence of the before-mentioned bacteria in 760 nucleic acid extracts of I. ricinus ticks detached from humans, which were previously tested for B. burgdorferi s.l.. A gltA gene-based amplicon sequencing approach was performed to identify Rickettsia species. The prevalence of Rickettsia spp. (16.7%, n = 127) and W. pipientis (15.9%, n = 121) were similar, while A. phagocytophilum was found in 2.8% (n = 21) and N. mikurensis in 0.1% (n = 1) of all ticks. Co-infection of B. burgdorferi s. l. with Rickettsia spp. was most frequent. The gltA gene sequencing indicated that Rickettsia helvetica was the dominant Rickettsia species in tick microbiomes. Moreover, R, monacensis and R. raoultii were correlated with autumn and area south, respectively, and a negative B. burgdorferi s. l. finding. Almost every fifth tick carried DNA of at least two of the human pathogenic bacteria studied here.

Terrestrial and Subterranean Mammals as Reservoirs of Zoonotic Diseases in the Central Part of European Russia

Russia has a number of historical foci of zoonotic anthropogenic diseases. In Central Russia, the Republic of Mordovia is one of such areas, a region being known to have foci of haemorrhagic fever with renal syndrome (HFRS) and tularemia. It therefore requires continuous monitoring. The role of small terrestrial mammals as reservoirs of zoonoses has been previously proven for the region. The aim of this work is to take an integrated approach to assess the role of terrestrial and subterranean small mammals. Subterranean mammals are often not considered important reservoirs of zoonotic pathogens that cause human morbidity. Among small mammals in the wild environment, the bank vole, the yellow-necked mouse and the house mouse play important roles as vectors of zoonoses. Among wild subterranean mammals, the greater mole rat is important as a vector of tularemia and HFRS. We analyzed homogenized internal organs of these animals (lungs, spleen, kidneys). Of all samples from the greater mole rat, 83% were positive for tularemia antigens and 17% were positive forHFRS. None of the analyzed European moles had antigens of tularemia and HFRS. No double infection with both tularemia and hantavirus was detected in the subterranean mammals. Double infection was found among terrestrial mammals in the bank vole and the forest dormouse.

Current Data on Rickettsia felis Occurrence in Vectors, Human and Animal Hosts in Europe: A Scoping Review

Rickettsia felis is an emerging pathogen with increasing reports of human cases and detection in arthropod and animal host species worldwide. In this scoping review we record the newest data reported for R. felis in Europe: the vector and host species found to be infected, and the geographical distribution and prevalence of R. felis infection in vectors and hosts. A total of 15 European countries reported the occurrence of R. felis in hosts and vectors during 2017−2022. The vectors found to be infected by R. felis were flea, tick and mite species; Ctenocephalides felis and Ixodes ricinus were the dominant ones. The hosts found to be infected and/or exposed to R. felis were humans, cats and small mammals. Physicians should be aware of the epidemiology and include illness caused by R. felis in the differential diagnosis of febrile disease. Veterinarians should keep training pet owners on the need for effective year-round arthropod control on their pets, especially for fleas.

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

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

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.

Culture Isolate of Rickettsia felis from a Tick

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

Seroprevalence of antibodies against Borrelia burgdorferi sensu lato in healthy blood donors in Romania: an update

BACKGROUND

The Borrelia burgdorferi sensu lato (s.l.) genogroup is the causative agent responsible for Lyme borreliosis, a common tick-borne infectious disease in some temperate regions of the Northern Hemisphere. In humans, the clinical manifestations of Lyme borreliosis vary from dermatological infection to severe systemic manifestations. In Romania, data on the seroprevalence of Lyme borreliosis and associated risk factors are scarce and outdated, as the only seroprevalence study with a large dataset was published more than 20 years ago. Therefore, the aim of the present study was to evaluate the seroprevalence for Borrelia burgdorferi s.l. in healthy blood donors from six Romanian counties and identify the associated risk factors.

METHODS

The study was conducted among 1200 healthy blood donors aged between 18 and 65 years during November 2019 and September 2020 from six counties in the northwestern and central parts of Romania. A two-tiered testing strategy was applied. Positive and equivocal immunoenzymatic test results for IgG and IgM antibodies were further confirmed by Western blot.

RESULTS

Serum samples from 20% of the blood donors had positive or equivocal IgG and IgM ELISA index values. In total, 2.3% of the serum samples for IgG and 1.8% for IgM were positive by Western blot. The seroprevalence for both antibodies varied between 1.5% (Satu-Mare) and 6.5% (Bistrița-Năsăud) in the six counties investigated. The highest seroprevalence was observed in men (4.7%), in blood donors performing their professional activities outdoors (4.2%), and in those aged  ≥ 56 years (8%).

CONCLUSIONS

These findings confirm the presence of specific IgG and IgM antibodies to B. burgdorferi s.l. among healthy blood donors from Romania. Furthermore, potential risk factors, such as gender, age, and behavior, associated with the presence of positive B. burgdorferi s.l. antibodies among healthy blood donors were identified.

The Role of Ticks in the Emergence of Borrelia burgdorferi as a Zoonotic Pathogen and Its Vector Control: A Global Systemic Review

Ticks are widely distributed across the globe, serving as hosts for numerous pathogens that make them major contributors to zoonotic parasitosis. Borrelia burgdorferi is a bacterial species that causes an emerging zoonotic tick-borne disease known as Lyme borreliosis. The role of ticks in the transmission of this pathogen was explored in this study. According to this systematic review, undertaken according to Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines, 19 tick species are known to carry Borrelia burgdorferi, with more than half of the recorded cases in the last two decades related to Ixodes ricinus and Ixodes scapularis ticks. Forty-six studies from four continents, Europe, North America, Asia, and Africa, reported this pathogen in ticks collected from vegetation, animals, and humans. This study highlights an increasing distribution of tick-associated Borrelia burgdorferi, likely driven by accelerated tick population increases in response to climate change coupled with tick dispersal via migratory birds. This updated catalogue helps in compiling all tick species responsible for the transmission of B. burgdorferi across the globe. Gaps in research exist on Borrelia burgdorferi in continents such as Asia and Africa, and in considering environmentally friendly vector control strategies in Europe and North America.

Protozoan and Microbial Pathogens of House Cats in the Province of Tekirdag in Western Turkey

Domestic felines’ re-emerging infectious and neglected zoonotic diseases are a significant focus of global “One Health” efforts. This study aimed to rapidly diagnose 14 pathogens, including zoonoses by using PCR primers in 167 client-owned symptomatic cats, routinely accepted to the Veterinary Clinics of Tekirdag. The prevalence of pathogens investigated were as follows: Babesia canis canis (24%), Babesia microti (2.4%), Hepatozoon felis (10.8%), Cytauxzoon felis (6.6%), Bartonella henselae (40.1%), Anaplasma platys (30.5%), Anaplasma phagocytophilum (7.2%), Rickettsia felis (26.3%), Borrelia burgdorferi (21%), and hemotropic Mycoplasma sp. (11.4%). There was a significant difference between the prevalence of the pathogens (χ² = 152.26, df = 9, p < 0.001). There was also a statistical difference between the gender of the cats in terms of the prevalence of all pathogens considered together (χ² = 4.80, df = 1, p = 0.028), where the female cats showed a higher prevalence. This was not the case for the different age groups (χ² = 2.92, df = 1, p = 0.088). The lowest infection was observed for B. microti (p < 0.001), while the highest infection was observed for B. henselae (p < 0.01). Leishmania donovani, Plasmodium spp., Ehrlichia chaffeensis, and Neoehrlichia mikurensis PCR test results were negative in all samples. In conclusion, house cats of Tekirdag are apparently highly susceptible to some neglected zoonoses important for “One Health”, and their prevalence in the region is most probably underestimated. Hence, applying PCR tests to assist fast clinic diagnosis in routine, may be an efficient option to protect the public as well as the cats from severe diseases.

Prevalence of unculturable bacteria in the periapical abscess: A systematic review and meta-analysis

OBJECTIVE

To assess the prevalence of unculturable bacteria in periapical abscess, radicular cyst, and periapical granuloma.

METHODS

PubMed, Scopus, Science Direct, and Ovid databases were systematically searched from January 1990 to May 2020. All the included studies were cross-sectional design. The risk of bias was assessed using Joanna Briggs Institute check-list. Heterogeneity was described using meta-regression and mixed-effects model for lesion, country, and sequence technique moderators. Funnel plot and unweighted Egger's regression test were used to estimate the publication bias. Microbiome data on diversity, abundance, and frequency of unculturable bacteria in the periapical lesions were reviewed, analysed, and the principal component analysis (PCA) was performed.

RESULTS

A total of 13 studies out of 14,780, were selected for the final analysis. These studies focused on the prevalence of unculturable bacteria in periapical abscesses and related lesions. Approximately 13% (95% CI: 7-23%) of the cumulative number of bacteria derived from periapical abscesses was unculturable. Country moderator significantly (P = 0.05) affects the diversity summary proportion. While the pooled frequency of unculturable bacteria was 8%; 95% CI: 5, 14%, the estimate of the pooled abundance of unculturable bacteria was 5%; 95% CI: 2, 12% with a significant (P = 0.05) country moderator that affects the abundance summary proportion. Of the 62 unculturable bacteria, 35 were subjected to PCA and Peptostreptococcus sp. oral clone CK035 was the most abundant species in periapical abscesses. Hybridization techniques were found to be the most reliable molecular methods in detecting the abundance and frequency of unculturable bacteria.

CONCLUSION

The significant prevalence of unculturable bacteria in the periapical abscess, suggests that they are likely to play, a yet unknown, critical role in the pathogenesis and progression of the disease. Further research remains to be done to confirm their specific contributions in the virulence and disease progression.