Migratory birds as disseminators of ticks and the tick-borne pathogens Borrelia bacteria and tick-borne encephalitis (TBE) virus: a seasonal study at Ottenby Bird Observatory in South-eastern Sweden

Viral pathogen detection in U.S. game-farm mallard (Anas platyrhynchos) flags spillover risk to wild birds

The threat posed by emerging infectious diseases is a major concern for global public health, animal health and food security, and the role of birds in transmission is increasingly under scrutiny. Each year, millions of mass-reared game-farm birds are released into the wild, presenting a unique and a poorly understood risk to wild and susceptible bird populations, and to human health. In particular, the shedding of enteric pathogens through excrement into bodies of water at shared migratory stop-over sites, and breeding and wintering grounds, could facilitate multi-species long-distance pathogen dispersal and infection of high numbers of naive endemic birds annually. The Mallard (Anas platyrhynchos) is the most abundant of all duck species, migratory across much of its range, and an important game species for pen-rearing and release. Major recent population declines along the US Atlantic coast has been attributed to game-farm and wild mallard interbreeding and the introduction maladaptive traits into wild populations. However, pathogen transmission and zoonosis among game-farms Mallard may also impact these populations, as well as wildlife and human health. Here, we screened 16 game-farm Mallard from Wisconsin, United States, for enteric viral pathogens using metatranscriptomic data. Four families of viral pathogens were identified - Picobirnaviridae (Genogroup I), Caliciviridae (Duck Nacovirus), Picornaviridae (Duck Aalivirus) and Sedoreoviridae (Duck Rotavirus G). To our knowledge, this is the first report of Aalivirus in the Americas, and the first report of Calicivirus outside domestic chicken and turkey flocks in the United States. Our findings highlight the risk of viral pathogen spillover from peri-domestically reared game birds to naive wild bird populations.

Anaplasma phagocytophilum in Ticks Blood-Feeding on Migratory Birds in Sweden

Migratory birds play a dual role as potential reservoirs of tick-borne pathogens, and potential dispersers of pathogen-containing ticks during their migratory journeys. Ixodes ricinus, a prevalent tick species in Northern and Western Europe, serves as a primary vector for Anaplasma phagocytophilum-a bacterium with implications for human and animal health. There is limited information available regarding A. phagocytophilum in birds. Our investigation focused on A. phagocytophilum prevalence in ticks collected from migratory birds in southeastern Sweden. The identification of ticks involved both molecular analyses for species determination and morphological classification to ascertain the developmental stage. The presence of A. phagocytophilum was determined using real-time PCR. Of the 1115 ticks analyzed from 4601 birds, 0.9% (n = 10), including I. ricinus and Ixodes frontalis, tested positive for A. phagocytophilum. Notably, common blackbirds (Turdus merula) yielded the highest number of A. phagocytophilum-infected ticks. The findings suggest that A. phagocytophilum is present in a small proportion of ticks infesting migratory birds in southeastern Sweden. Consequently, the role of birds as hosts for ticks infected with A. phagocytophilum appears to be low, suggesting that birds seem to play a minor indirect role in the geographic dispersal of A. phagocytophilum.

Human Tick-Borne Diseases and Advances in Anti-Tick Vaccine Approaches: A Comprehensive Review

This comprehensive review explores the field of anti-tick vaccines, addressing their significance in combating tick-borne diseases of public health concern. The main objectives are to provide a brief epidemiology of diseases affecting humans and a thorough understanding of tick biology, traditional tick control methods, the development and mechanisms of anti-tick vaccines, their efficacy in field applications, associated challenges, and future prospects. Tick-borne diseases (TBDs) pose a significant and escalating threat to global health and the livestock industries due to the widespread distribution of ticks and the multitude of pathogens they transmit. Traditional tick control methods, such as acaricides and repellents, have limitations, including environmental concerns and the emergence of tick resistance. Anti-tick vaccines offer a promising alternative by targeting specific tick proteins crucial for feeding and pathogen transmission. Developing vaccines with antigens based on these essential proteins is likely to disrupt these processes. Indeed, anti-tick vaccines have shown efficacy in laboratory and field trials successfully implemented in livestock, reducing the prevalence of TBDs. However, some challenges still remain, including vaccine efficacy on different hosts, polymorphisms in ticks of the same species, and the economic considerations of adopting large-scale vaccine strategies. Emerging technologies and approaches hold promise for improving anti-tick vaccine development and expanding their impact on public health and agriculture.

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.

Ixodid ticks from wild and domestic animals in East and Central Asian flyways

Tick-borne diseases have a significant impact on human and animal populations, posing an increasing threat to public health, particularly in the context of climate change. Along with the various natural hosts of ticks, birds play a notable role in transmitting ticks and tick-borne pathogens, indicating the importance of monitoring flyways and establishing a cooperative network for comprehensive surveillance and to collect diverse tick samples across various regions. This study aimed to develop an international network for surveillance of disease, collection of sufficient tick samples, and overall identification of the geographical distribution of host and ticks in Asian regions, especially in 11 countries on East Asian and Central Asian flyways. Ticks were collected from wild animals, domestic animals, and vegetation to identify the differences between Ixodid ticks and understand tick distribution. We collected a total 6,624 of ticks from 11 collaborating Asian countries, the Republic of Korea (ROK), Japan, Thailand, Philippines, Indonesia, Cambodia, Vietnam, Taiwan, Hong Kong, Mongolia and Pakistan. We identified 17 host animals and 47 species of both residential and migratory birds. Ticks from birds collected from four countries (ROK, Japan, Hong Kong and Mongolia) belonged to two genera, Haemaphysalis and Ixodes, including Haemaphysalis (H.) longicornis, H. flava, H. concinna, H. hystricis, H. formosensis, Ixodes (I.) nipponensis and I. persulcatus. The potential of migratory birds to cross ecological barriers with ticks and tick-borne diseases indicated the need for further investigations to understand the migration of birds as potential vectors and the new influx of zoonotic diseases along migratory bird flyways. This study suggests the potential risk of spreading tick-borne diseases through birds, thus highlighting the importance of international cooperative networking.

Bidirectional tick transport by migratory birds of the African-Western Palearctic flyway over Turkish Thrace: observation of the current situation and future projection

This study was carried out at a vital stopover site of migrating birds in the Turkish Thrace, European part of Turkey, on the Mediterranean/Black Sea Flyway. Ticks were collected from the birds captured in the four migration periods, i.e., autumn 2020, spring 2021, autumn 2021, and spring 2022, and identified morphologically. Throughout the study, 10,651 birds from 77 species were examined, and 671 belonging to 34 species were found infested. The infestation prevalence in total birds and the mean number of ticks per infested bird were 6.3% and 3.8 (range: 1-142), respectively. A total of 2573 ticks were collected with the following species distribution and numbers: Ixodes spp. 70 larvae, I. frontalis 1829 larvae, 337 nymphs, and 30 adults, I. acuminatus 16 nymphs and 42 adults, I. ricinus 39 larvae, 141 nymphs, and one adult, Hyalomma spp. seven larvae and 60 nymphs, and Haemaphysalis sp. one larva. Prevalence, intensity, and species distribution of the ticks in birds varied depending on the month, season, year, and species-specific migration phenology of the birds. The results show that precise determination of the tick-borne risk associated with migratory birds for a particular region necessarily requires long-term and comprehensive studies and indicates that anthropogenic climate change and habitat degradation can significantly differentiate the risk by influencing the migration phenology in birds and by making new regions suitable for the establishment of different ticks.

Tick-Borne Encephalitis-Review of the Current Status

The tick-borne encephalitis virus (TBEV) is the arboviral etiological agent of tick-borne encephalitis (TBE), considered to be one of the most important tick-borne viral diseases in Europe and Asia. In recent years, an increase in the incidence of TBE as well as an increasing geographical range of the disease have been noted. Despite the COVID-19 pandemic and the imposition of restrictions that it necessitated, the incidence of TBE is rising in more than half of the European countries analyzed in recent studies. The virus is transmitted between ticks, animals, and humans. It seems that ticks and small mammals play a role in maintaining TBEV in nature. The disease can also affect dogs, horses, cattle, and small ruminants. Humans are incidental hosts, infected through the bite of an infected tick or by the alimentary route, through the consumption of unpasteurized milk or milk products from TBEV-infected animals. TBEV infections in humans may be asymptomatic, but the symptoms can range from mild flu-like to severe neurological. In Europe, cases of TBE are reported every year. While there is currently no effective treatment for TBE, immunization and protection against tick bites are critical in preventing this disease.

Tick-Borne Encephalitis Virus: A Comprehensive Review of Transmission, Pathogenesis, Epidemiology, Clinical Manifestations, Diagnosis, and Prevention

Tick-borne encephalitis virus (TBEV), a member of the Flaviviridae family, can cause serious infection of the central nervous system in humans, resulting in potential neurological complications and fatal outcomes. TBEV is primarily transmitted to humans through infected tick bites, and the viral agent circulates between ticks and animals, such as deer and small mammals. The occurrence of the infection aligns with the seasonal activity of ticks. As no specific antiviral therapy exists for TBEV infection, treatment approaches primarily focus on symptomatic relief and support. Active immunization is highly effective, especially for individuals in endemic areas. The burden of TBEV infections is increasing, posing a growing health concern. Reported incidence rates rose from 0.4 to 0.9 cases per 100,000 people between 2015 and 2020. The Baltic and Central European countries have the highest incidence, but TBE is endemic across a wide geographic area. Various factors, including social and environmental aspects, improved medical awareness, and advanced diagnostics, have contributed to the observed increase. Diagnosing TBEV infection can be challenging due to the non-specific nature of the initial symptoms and potential co-infections. Accurate diagnosis is crucial for appropriate management, prevention of complications, and effective control measures. In this comprehensive review, we summarize the molecular structure of TBEV, its transmission and circulation in natural environments, the pathogenesis of TBEV infection, the epidemiology and global distribution of the virus, associated risk factors, clinical manifestations, and diagnostic approaches. By improving understanding of these aspects, we aim to enhance knowledge and promote strategies for timely and accurate diagnosis, appropriate management, and the implementation of effective control measures against TBEV infections.

Metagenomics Characterization of Ixodes ricinus Intestinal Microbiota as Major Vector of Tick-Borne Diseases in Domestic Animals

Background

Understanding the microbiota of disease vectors can help for developing new strategies to prevent the transmission of vector pathogens. Ixodes ricinus is one of the most notorious tick vectors with increasing importance in Iran and other parts of the world while there is limited data on its microbiota. This study aimed to use metagenomics for identifying the I. ricinus tick's microbiota of Iran.

Methods

A total of 39 adult ticks were collected from Mazandaran (21 females), Gilan (17 females), and Golestan (1 male). Five tick pools prepared from 39 adults of I. ricinus were subjected to metagenomics analysis. The data were analyzed by targeting the V6 region of the 16S rRNA gene by Illumina 4000 Hiseq sequencing.

Results

Among hundreds of intestinal microbiota identified by metagenomics, various pathogenic microorganisms distributed in 30 genera and species including those responsible for tick-borne diseases resided in the genera Coxiella, Rickettsia, and Burkholderia were found.

Conclusion

Our results indicated that metagenomics identifies bacteria genera and species which cannot be easily recognized by routine methods. The presence of such pathogenic bacteria indicates the importance of possible zoonotic diseases in this region which could affect public health. These results further substantiate the importance of advanced metagenomics analyses to identify neglected tick-borne pathogens which enable researchers to provide efficient mapping roads for the management of emerging and re-emerging infectious diseases.

Genetic Diversity of Borreliaceae Species Detected in Natural Populations of Ixodes ricinus Ticks in Northern Poland

In Europe, Ixodes ricinus tick is the vector of Lyme disease spirochetes and their relatives (Borreliella genus) and Borrelia miyamotoi. However, a newly described tick I. inopinatus with similar biological features and separated from I. ricinus may act as a vector for different Borrelia species. To date, eleven Borreliella species were detected in the natural populations of I. ricinus. Recently, two North American species have been detected in ticks parasitizing bats and red foxes in Europe, i.e., B. lanei and B. californiensis pointing to the necessity for searching for them in natural tick populations. In this study, using the coxI molecular marker only I. ricinus was identified in field-collected ticks with the exception of individual specimens of Haemaphysalis concinna. Using the flaB gene and mag-trnI intergenic spacer as molecular markers 14 Borreliaceae species have been detected with various frequencies in different parts of northern Poland. Among infected ticks, the most frequent were Borreliella (Bl.) afzelii (29.4%) and Bl. garinii (20.0%), followed by Bl. spielmanii, Bl. valaisiana, Bl. lanei, Bl. californiensis, B. miyamotoi, Bl. burgdorferi, Bl. carolinensis, Bl. americana, B. turcica, Bl. lusitaniae, Bl. bissettiae and Bl. finlandensis. Three of the above-mentioned species, i.e., Bl. lanei, Bl. californiensis and B. turcica were detected in this study for the first time in the natural ixodid tick population in Europe. The existence of the newly detected spirochetes increases their total diversity in Europe and points to the necessity of careful identification and establishment of the actual distribution of all Borreliaceae species transmitted by I. ricinus.

Lyme Neuroborreliosis—Significant Local Variations in Incidence within a Highly Endemic Region in Sweden

The aim of this study was to perform a detailed epidemiological overview of Lyme neuroborreliosis (LNB) 2008–2021 in a highly Lyme borreliosis-endemic area in Sweden using a geographic information system (GIS). Diagnosis of LNB was based on clinical symptoms and analysis of cerebrospinal fluid (CSF) according to European guidelines. From laboratory databases and medical records, we detected all patients with CSF pleocytosis and intrathecal anti-Borrelia antibody production and listed clinical features. The distribution of LNB cases within Kalmar County, Sweden was investigated using GIS. In total, 272 cases of definite LNB were confirmed with an average yearly incidence of 7.8/100,000. Significant differences in incidence were noted between children 0–17 years (16/100,000) and adults 18+ years (5.8/100,000) (p < 0.001), between rural (16/100,000) and urban areas (5.8/100,000) (p < 0.001) and between selected municipalities (p < 0.001). Distinct clinical differences in presentation of LNB were also noted between children and adults. Thus, the incidence of LNB varies significantly locally and in relation to age, and clinical presentation shows differences between children and adults. Surveillance of LNB and knowledge of local epidemiological conditions may facilitate preventive measures.

First Expert Elicitation of Knowledge on Possible Drivers of Observed Increasing Human Cases of Tick-Borne Encephalitis in Europe

Tick-borne encephalitis (TBE) is a viral disease endemic in Eurasia. The virus is mainly transmitted to humans via ticks and occasionally via the consumption of unpasteurized milk products. The European Centre for Disease Prevention and Control reported an increase in TBE incidence over the past years in Europe as well as the emergence of the disease in new areas. To better understand this phenomenon, we investigated the drivers of TBE emergence and increase in incidence in humans through an expert knowledge elicitation. We listed 59 possible drivers grouped in eight domains and elicited forty European experts to: (i) allocate a score per driver, (ii) weight this score within each domain, and (iii) weight the different domains and attribute an uncertainty level per domain. An overall weighted score per driver was calculated, and drivers with comparable scores were grouped into three terminal nodes using a regression tree analysis. The drivers with the highest scores were: (i) changes in human behavior/activities; (ii) changes in eating habits or consumer demand; (iii) changes in the landscape; (iv) influence of humidity on the survival and transmission of the pathogen; (v) difficulty to control reservoir(s) and/or vector(s); (vi) influence of temperature on virus survival and transmission; (vii) number of wildlife compartments/groups acting as reservoirs or amplifying hosts; (viii) increase of autochthonous wild mammals; and (ix) number of tick species vectors and their distribution. Our results support researchers in prioritizing studies targeting the most relevant drivers of emergence and increasing TBE incidence.

Borrelia miyamotoi: A Comprehensive Review

Borrelia miyamotoi is an emerging tick-borne pathogen in the Northern Hemisphere and is the causative agent of Borrelia miyamotoi disease (BMD). Borrelia miyamotoi is vectored by the same hard-bodied ticks as Lyme disease Borrelia, yet phylogenetically groups with relapsing fever Borrelia, and thus, has been uniquely labeled a hard tick-borne relapsing fever Borrelia. Burgeoning research has uncovered new aspects of B. miyamotoi in human patients, nature, and the lab. Of particular interest are novel findings on disease pathology, prevalence, diagnostic methods, ecological maintenance, transmission, and genetic characteristics. Herein, we review recent literature on B. miyamotoi, discuss how findings adapt to current Borrelia doctrines, and briefly consider what remains unknown about B. miyamotoi.

Ornithological and molecular evidence of a reproducing Hyalomma rufipes population under continental climate in Europe

Reports on adult Hyalomma ticks in certain regions of the Carpathian Basin date back to the 19th century. These ticks were thought to emerge from nymphs dropping from birds, then molting to adults. Although the role of migratory birds in carrying ticks of this genus is known from all parts of Europe, in most countries no contemporaneous multiregional surveillance of bird-associated ticks was reported which could allow the recognition of hotspots in this context. From 38 passeriform bird species 956 ixodid ticks were collected at seven locations in Hungary. Tick species were identified as Ixodes ricinus (n = 598), Ixodes frontalis (n = 18), Ixodes lividus (n = 6), Haemaphysalis concinna (n = 321), and D. reticulatus (n = 1). All 12 Hyalomma sp. ticks (11 engorged nymphs and 1 unengorged larva) were identified as H. rufipes based on three mitochondrial markers. This species was only found in the Transdanubian region and along its southeastern border. The Common Blackbird and the European Robin were the two main hosts of I. ricinus and I. frontalis, whereas H. concinna was almost exclusively collected form long-distance migrants. The predominant hosts of H. rufipes were reed-associated bird species, the Sedge Warbler and the Bearded Reedling, both in their nesting period. This study provides ornithological explanation for the regional, century-long presence of adult Hyalomma ticks under continental climate in the Transdanubian Region of the Carpathian Basin. More importantly, the autochthonous occurrence of a H. rufipes population was revealed for the first time in Europe, based on the following observations: (1) the bird species infested with H. rufipes are not known to migrate during their nesting period; (2) one larva was not yet engorged; (3) the larva and the nymphs must have belonged to different local generations; and (4) all H. rufipes found in the relevant location were identical in their haplotypes based on three maternally inherited mitochondrial markers, probably reflecting founder effect. This study also demonstrated regional and temporal differences in tick species carried by birds.

Serologic Investigation on Tick-Borne Encephalitis Virus, Kemerovo Virus and Tribeč Virus Infections in Wild Birds

The present study reports on serosurvey on the tick-borne encephalitis virus European subtype (TBEV; genus Flavivirus), and the tick-borne Kemerovo (KEMV) and Tribeč (TRBV) orbivirus (genus Orbivirus) infections in tick-infested and non-infested birds. No virus RNA was detected in the blood clots. Birds were infested mostly by Ixodes ricinus, but Haemaphysalis concinna and I. frontalis were observed too. TBEV, KEMV and TRBV neutralising antibodies (NAb) were detected in the screening microtitration neutralisation test (μVNT). Seropositive samples were further examined in simultaneous μVNT to distinguish TBEV infection from WNV and USUV. KEMV and TRBV infections were also further examined by μVNT against each other. The demonstrated results point to increased TBEV and TRBV seroprevalence in birds over the past several years. This is the first study on KEMV infection in the Slovak bird population, and seropositive juvenile birds suggest its occurrence in a new geographic area. The results indicate the significance of tick infestation rates, seropositivity and specific NAb titre. The reservoir role of birds for TBEV, KEMV and TRBV remains unclear. However, targeted monitoring of birds and vectors is an effective measure of surveillance of arbovirus introduction into new geographic areas.

Climate Crises and Developing Vector-Borne Diseases: A Narrative Review

Background

Climate change based on temperature, humidity and wind can improve many characteristics of the arthropod carrier life cycle, including survival, arthropod population, pathogen communication, and the spread of infectious agents from vectors. This study aimed to find association between content of disease followed climate change we demonstrate in humans.

Methods

All the articles from 2016 to 2021 associated with global climate change and the effect of vector-borne disease were selected form databases including PubMed and the Global Biodiversity information facility database. All the articles selected for this short review were English.

Results

Due to the high burden of infectious diseases and the growing evidence of the possible effects of climate change on the incidence of these diseases, these climate changes can potentially be involved with the COVID-19 epidemic. We highlighted the evidence of vector-borne diseases and the possible effects of climate change on these communicable diseases.

Conclusion

Climate change, specifically in rising temperature system is one of the world's greatest concerns already affected pathogen-vector and host relation. Lice parasitic, fleas, mites, ticks, and mosquitos are the prime public health importance in the transmission of virus to human hosts.

Tick-Borne Encephalitis Virus RNA Found in Frozen Goat's Milk in a Family Outbreak

Tick-borne encephalitis (TBE) is one of the commonest arthropod-borne viral diseases in Middle-East Europe and North Asia. The main reservoir of the virus is comprised of small rodents and domestic mammals with the common tick (Ixodes) being the usual vector. The clinical spectrum of TBE ranges from mild meningitis to severe meningoencephalomyelitis. This disease can lead to severe sequelae and has a mortality up to 2% in Europe. Even though the majority of cases are transmitted through bites of infected ticks, infections through ingestion of contaminated milk and dairy products from farms in endemic areas have been reported. We report a family outbreak of a febrile disease, initially suggestive of human-to-human infection, during the early summertime in Austria. Tick-borne encephalitis was diagnosed following consumption of unpasteurised goat’s milk and the virus was subsequently detected in frozen milk samples. Although this is a rare manifestation of TBE, this case series shows that TBE should be included in the differential diagnosis of an outbreak of febrile disease, and a careful clinical history with reference to unpasteurized dairy products is crucial in order to prevent further disease spread. The best preventive measure is active immunisation of people living in, or travelling to, endemic areas.

Hard ticks (Acari: Ixodidae) associated with birds in Europe: Review of literature data

Hard ticks (Acari: Ixodidae) are considered the most important transmitters of pathogens in the temperate zone that covers most of Europe. In the era of climate change tick-borne diseases are predicted to undergo geographical range expansion toward the north through regions that are connected to southern areas of the continent by bird migration. This alone would justify the importance of synthesized knowledge on the association of tick species with avian hosts, yet birds also represent the most taxonomically and ecologically diverse part of urban vertebrate fauna. Birds frequently occur in gardens and near animal keeping facilities, thus playing a significant role in the dispersal of ticks and tick-borne pathogens in synanthropic environments. The primary aim of this review is to provide a comprehensive reference source (baseline data) for future studies, particularly in the context of discovering new tick-host associations after comparison with already published data. The records on the ixodid tick infestations of birds were assessed from nearly 200 papers published since 1952. In this period, 37 hard tick species were reported from 16 orders of avian hosts in Europe. Here we compile a list of these tick species, followed by the English and Latin name of all reported infested bird species, as well as the tick developmental stage and country of origin whenever this information was available. These data allowed a first-hand analysis of general trends regarding how and at which developmental stage of ticks tend to infest avian hosts. Five tick species that were frequently reported from birds and show a broad geographical distribution in the Western Palearctic (Ixodes arboricola, I. frontalis, I. ricinus, Haemaphysalis concinna and Hyalomma marginatum) were also selected for statistical comparisons. Differences were demonstrated between these tick species regarding their association with bird species that typically feed from the ground and those that rarely occur at the soil level. The ecology of these five bird-infesting tick species is also illustrated here according to avian orders, taking into account the ecology (habitat type) and activity (circadian rhythm and feeding level) of most bird species that represent a certain order.

Diversity of Tick-Borne Pathogens in Tick Larvae Feeding on Breeding Birds in France

Birds play a role in maintaining tick-borne diseases by contributing to the multiplication of ticks and pathogens on a local scale during the breeding season. In the present study, we describe the diversity of tick and pathogen species of medical and veterinary importance in Europe hosted by 1040 captured birds (56 species) during their breeding season in France. Of the 3114 ticks collected, Ixodes ricinus was the most prevalent species (89.5%), followed by I. frontalis (0.8%), I. arboricola (0.7%), Haemaphysalis concinna (0.5%), H. punctata (0.5%), Hyalomma spp. (0.2%), and Rhipicephalus spp. (0.06%). Because they may be representative of the bird infection status for some pathogen species, 1106 engorged tick larvae were screened for pathogens. Borrelia burgdorferi sensu lato was the most prevalent pathogen genus in bird-feeding larvae (11.7%), followed by Rickettsia spp. (7.4%), Anaplasma spp. (5.7%), Babesia spp. (2.3%), Ehrlichia spp. (1.4%), and B. miyamotoi (1%). Turdidae birds (Turdus merula and T. philomelos), Troglodytes troglodytes, and Anthus trivialis had a significantly higher prevalence of B. burgdorferi s.l.-infected larvae than other pathogen genera. This suggests that these bird species could act as reservoir hosts for B. burgdorferi s.l. during their breeding season, and thus play an important role in acarological risk.

Toxoplasma gondii and Rickettsia spp. in ticks collected from migratory birds in the Republic of Korea

Migratory birds disperse ticks and associated tick-borne pathogens along their migratory routes. Four selected pathogens of medical importance (Coxiella burnetii, Rickettsia spp., Francisella tularensis, and Toxoplasma gondii) were targeted for detection in 804 ticks (365 pools) collected from migratory birds at Hong and Heuksan Islands in the Republic of Korea (ROK) from 2010 to 2011 and 2016. Toxoplasma gondii and Rickettsia spp., were detected in 1/365 (0.27%) and 34/365 (9.32%) pools of ticks, respectively. T. gondii and five rickettsial species were recorded in ticks collected from migratory birds for the first time in ROK. The five rickettsial species (R. monacensis, Candidatus Rickettsia longicornii, R. japonica, R. raoultii, and R. tamurae) were identified using sequence and phylogenetic analysis using ompA and gltA gene fragments. Rickettsia spp. are important pathogens that cause rickettsiosis in humans, with cases recorded in the ROK. These results provide important evidence for the potential role of migratory birds in the introduction and dispersal of T. gondii and Rickettsia spp. along their migratory routes and raise awareness of potential transmission of zoonotic tick-borne pathogens associated with migratory birds in the ROK.

Diversity and Genetic Structure of Theileria annulata in Pakistan and Other Endemic Sites

Background: Theileria annulata is a tick-borne protozoan parasite responsible for bovine theileriosis, a disease that impacts cattle population in many developing countries. Development and deployment of effective control strategies, based on vaccine or therapy, should consider the extent of diversity of the parasite and its population structure in different endemic areas. In this study, we examined T. annulata in Pakistan and carried out a comparative analysis with similar data garneted in other areas, to provide further information on the level of parasite diversity and parasite genetic structure in different endemic areas. Methods: The present study examined a set of 10 microsatellites/minisatellites and analyzed the genetic structure of T. annulata in cattle breeds from Pakistan (Indian sub-continent) and compared these with those in Oman (Middle East), Tunisia (Africa), and Turkey (Europe). Result: A high level of genetic diversity was observed among T. annulata detected in cattle from Pakistan, comparable to that in Oman, Tunisia, and Turkey. The genotypes of T. annulata in these four countries form genetically distinct groups that are geographically sub-structured. The T. annulata population in Oman overlapped with that in the Indian Subcontinent (Pakistan) and that in Africa (Tunisia). Conclusions: The T. annulata parasite in Pakistan is highly diverse, and genetically differentiated. This pattern accords well and complements that seen among T. annulata representing the global endemic site. The parasite population in the Arabian Peninsula overlapped with that in the Indian-Subcontinent (India) and that in Africa (Tunisia), which shared some genotypes with that in the Near East and Europe (Turkey). This suggests some level of parasite gene flow, indicative of limited movement between neighboring countries.

Spatial and temporal distribution patterns of tick-borne diseases (Tick-borne Encephalitis and Lyme Borreliosis) in Germany

BACKGROUND

In the face of ongoing climate warming, vector-borne diseases are expected to increase in Europe, including tick-borne diseases (TBD). The most abundant tick-borne diseases in Germany are Tick-Borne Encephalitis (TBE) and Lyme Borreliosis (LB), with Ixodes ricinus as the main vector.

METHODS

In this study, we display and compare the spatial and temporal patterns of reported cases of human TBE and LB in relation to some associated factors. The comparison may help with the interpretation of observed spatial and temporal patterns.

RESULTS

The spatial patterns of reported TBE cases show a clear and consistent pattern over the years, with many cases in the south and only few and isolated cases in the north of Germany. The identification of spatial patterns of LB disease cases is more difficult due to the different reporting practices in the individual federal states. Temporal patterns strongly fluctuate between years, and are relatively synchronized between both diseases, suggesting common driving factors. Based on our results we found no evidence that weather conditions affect the prevalence of both diseases. Both diseases show a gender bias with LB bing more commonly diagnosed in females, contrary to TBE being more commonly diagnosed in males.

CONCLUSION

For a further investigation of of the underlying driving factors and their interrelations, longer time series as well as standardised reporting and surveillance system would be required.

Errata in East Coast tick study: retort to Tufts & Diuk-Wasser

The authors overlook the first report of Haemaphysalis punctata in the Western Hemisphere documented by a pioneer acarologist in 1910. The authors assume that climate change alters movement of ticks, but provide no data. The authors’ assumptions are only opinions, and must be corrected and challenged.

Zoonotic vector-borne bacteria in wild rodents and associated ectoparasites from Tunisia

Wild rodents are considered as potential carriers of several zoonotic vector-borne bacteria but their epidemiology is poorly understood in Tunisia. A total of 305 biological samples (100 spleens, 100 livers, 100 kidneys, and 5 pooled ectoparasites (Xenopsylla cheopis, Laelaps echidninus, Ornithonyssus sp., Hoplopleura sp. and eggs of the rat fleas)) were collected from 100 wild rodents from three Tunisian governorates. Molecular screening was performed to reveal infections with main vector-borne bacteria. Captured rodents belonged to three rodent genera and species including Rattus rattus (n = 51, 51%), Meriones shawi (n = 24, 24%) and Mus musculus (n = 25, 25%). Examined rodents were found to be heavily infested by the rat flea X. cheopis (n = 32, 47%) and the rat mite L. echidninus (n = 22, 32.3%). However, the rat mite Ornithonyssus sp. (n = 13, 19.1%) and the rat lice Hoplopleura sp. (n = 1, 1.5%) were rarely identified. Based on 16S rRNA and msp4 genes, infection with Anaplasmataceae bacteria was detected in six specimens of R. rattus and one M. shawi. Pathogenic A. phagocytophilum (n = 1), A. phagocytophilum-like 1 (Anaplasma sp. Japan) (n = 1), and A. ovis (n = 5) were identified. On the basis of ompB, ompA and gltA genes, infection with Rickettsia spp. was identified in three specimens of R. rattus and one of M. shawi. Five Rickettsia species of the spotted fever group, corresponding to R. monacensis, R. helvetica, R. massiliae, R. africae, and R. aeschlimannii, were detected in mixed infections. Bartonella henselae DNA was also found in two R. rattus, based on rpoB partial sequences. All revealed Anaplasma, Rickettsia and Bartonella bacteria were detected in spleen samples. Ehrlichia, Coxiella and Borrelia spp. were not identified in any of the tested samples. In Tunisia, this is the first report indicating infections with Anaplasma, Rickettsia and Bartonella spp. in wild rodents, particularly present alongside domestic livestock and human. This represents a serious risk of potential bacterial transmission. Thus, controlling rodent population in animal herds, residential areas and sensitizing local people to this risk seem absolutely necessary.

A new nairo-like virus associated with human febrile illness in China

Several nairo-like viruses have been discovered in ticks in recent years, but their relevance to public health remains unknown. Here, we found a patient who had a history of tick bite and suffered from a febrile illness was infected with a previously discovered RNA virus, Beiji nairovirus (BJNV), in the nairo-like virus group of the order Bunyavirales. We isolated the virus by cell culture assay. BJNV could induce cytopathic effects in the baby hamster kidney and human hepatocellular carcinoma cells. Negative-stain electron microscopy revealed enveloped and spherical viral particles, morphologically similar to those of nairoviruses. We identified 67 patients as BJNV infection in 2017–2018. The median age of patients was 48 years (interquartile range 41–53 years); the median incubation period was 7 days (interquartile range 3–12 days). Most patients were men (70%), and a few (10%) had underlying diseases. Common symptoms of infected patients included fever (100%), headache (99%), depression (63%), coma (63%), and fatigue (54%), myalgia or arthralgia (45%); two (3%) patients became critically ill and one died. BJNV could cause growth retardation, viremia and histopathological changes in infected suckling mice. BJNV was also detected in sheep, cattle, and multiple tick species. These findings demonstrated that the newly discovered nairo-like virus may be associated with a febrile illness, with the potential vectors of ticks and reservoirs of sheep and cattle, highlighting its public health significance and necessity of further investigation in the tick-endemic areas worldwide.

The evolution of hard tick-borne relapsing fever borreliae is correlated with vector species rather than geographical distance

Background

Relapsing fever (RF) borreliae are arthropod-borne spirochetes and some of them cause human diseases, which are characterized by relapsing or recurring episodes of fever. Recently, it has been classified into two groups: soft tick-borne RF (STRF) borreliae and hard tick-borne RF (HTRF) borreliae. STRF borreliae include classical RF agents and HTRF borreliae, the latter of which include B. miyamotoi, a human pathogen recently identified in Eurasia and North America.

Results

In this study, we determined the genome sequences of 16 HTRF borreliae strains: 15 B. miyamotoi strains (9 from Hokkaido Island, Japan, 3 from Honshu Island, Japan, and 3 from Mongolia) and a Borrelia sp. tHM16w. Chromosomal gene synteny was highly conserved among the HTRF strains sequenced in this study, even though they were isolated from different geographic regions and different tick species. Phylogenetic analysis based on core gene sequences revealed that HTRF and STRF borreliae are clearly distinguishable, with each forming a monophyletic group in the RF borreliae lineage. Moreover, the evolutionary relationships of RF borreliae are consistent with the biological and ecological features of each RF borreliae sublineage and can explain the unique characteristics of Borrelia anserina. In addition, the pairwise genetic distances between HTRF borreliae strains were well correlated with those of vector species rather than with the geographical distances between strain isolation sites. This result suggests that the genetic diversification of HTRF borreliae is attributed to the speciation of vector ticks and that this relationship might be required for efficient transmission of HTRF borreliae within vector ticks.

Conclusions

The results of the present study, together with those from previous investigations, support the hypothesis that the common ancestor of borreliae was transmitted by hard-bodied ticks and that only STRF borreliae switched to using soft-bodied ticks as a vector, which was followed by the emergence of Borrelia recurrentis, lice-borne RF borreliae. Our study clarifies the phylogenetic relationships between RF borreliae, and the data obtained will contribute to a better understanding of the evolutionary history of RF borreliae.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12862-021-01838-1.

First Record of a Suspected Human-Pathogenic Borrelia Species in Populations of the Bat Tick Carios vespertilionis in Sweden

The bat tick Cariosvespertilionis has been reported from Sweden to occasionally feed on humans resulting in disease symptoms. The aim of this study was to investigate C. vespertilionis as a potential vector and reservoir of Borrelia species. In 2015 and 2018 in south-central Sweden, C. vespertilionis ticks were collected from a wooden bat box harboring Soprano pipistrelle bats, Pipistrellus pygmaeus. In addition, one C. vespertilionis tick found inside a house in southern Sweden in 2019 was collected. Ticks were screened for Borrelia spp. using a genus-specific quantitative PCR assay. The Borrelia species of the positive specimens were determined by conventional PCR followed by DNA sequencing and phylogenetic analyses. A total of 24% (22 of 92) of the analyzed C. vespertilionis ticks were Borrelia-positive. Phylogenetic analyses indicate that the bacteria belong to the relapsing fever group of borreliae; some of them appear to be identical with Borrelia sp. CPB1, a spirochete only found twice before-in the United Kingdom and in France. Our results also indicate a temporal and spatial distribution of this Borrelia species. Since C. vespertilionis occasionally bites humans, and since it exhibits a high prevalence of Borrelia bacteria, it is possible that it presents a risk of human disease. Further studies are needed to characterize Borrelia sp. CPB1 to determine if it is human-pathogenic and to determine if C. vespertilionis is a vector and/or reservoir of this agent.

Three Babesia species in Ixodes ricinus ticks from migratory birds in Sweden

Background

Migratory birds can cross geographical and environmental barriers and are thereby able to facilitate transmission of tick-borne pathogens both as carriers of infected ticks and as reservoirs of pathogenic microorganisms. Ixodes ricinus is one of the most abundant tick species in the Northern Hemisphere and a main vector of several Babesia species, some which pose a potential threat to human and animal health. At present only two cases of overt babesiosis in humans have so far been reported in Sweden. To better understand the potential role of birds as disseminators of zoonotic Babesia protozoan parasites, we investigated the presence of Babesia species in ticks removed from migratory birds.

Methods

Ticks were collected from birds captured at Ottenby Bird Observatory, south-eastern Sweden, from March to November 2009. Ticks were molecularly identified to species, and morphologically to developmental stage, and the presence of Babesia protozoan parasites was determined by real-time PCR.

Results

In total, 4601 migratory birds of 65 species were examined for tick infestation. Ticks removed from these birds have previously been investigated for the presence of Borrelia bacteria and the tick-borne encephalitis virus. In the present study, a total of 1102 ticks were available for molecular analysis of Babesia protozoan parasites. We found that 2.4% of the ticks examined, all I. ricinus, were positive for mammal-associated Babesia species. Out of all Babesia-positive samples, Babesia venatorum was the most prevalent (58%) species, followed by Babesia microti (38%) and Babesia capreoli (4.0%). B. venatorum and B. capreoli were detected in I. ricinus larvae, whereas B. microti was only present in I. ricinus nymphs. This supports the view that the two first-mentioned species are vertically (transovarially) transmitted in the tick population, in contrast to B. microti. The largest number of Babesia-infected ticks was removed from the common redstart (Phoenicurus phoenicurus) and European robin (Erithacus rubecula).

Conclusions

This study reveals that Babesia protozoan parasites are present in ticks infesting migratory birds in south-eastern Sweden, which could potentially lead to the dissemination of these tick-borne microorganisms into new areas, thus posing a threat to humans and other mammals.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13071-021-04684-8.

The Impact of Tick-Borne Diseases on the Bone

Tick-borne infectious diseases can affect many tissues and organs including bone, one of the most multifunctional structures in the human body. There is a scarcity of data regarding the impact of tick-borne pathogens on bone. The aim of this review was to survey existing research literature on this topic. The search was performed using PubMed and Google Scholar search engines. From our search, we were able to find evidence of eight tick-borne diseases (Anaplasmosis, Ehrlichiosis, Babesiosis, Lyme disease, Bourbon virus disease, Colorado tick fever disease, Tick-borne encephalitis, and Crimean-Congo hemorrhagic fever) affecting the bone. Pathological bone effects most commonly associated with tick-borne infections were disruption of bone marrow function and bone loss. Most research to date on the effects of tick-borne pathogen infections on bone has been quite preliminary. Further investigation of this topic is warranted.

The Integration of Human and Veterinary Studies for Better Understanding and Management of Crimean-Congo Haemorrhagic Fever

Outbreaks that occur as a result of zoonotic spillover from an animal reservoir continue to highlight the importance of studying the disease interface between species. One Health approaches recognise the interdependence of human and animal health and the environmental interplay. Improving the understanding and prevention of zoonotic diseases may be achieved through greater consideration of these relationships, potentially leading to better health outcomes across species. In this review, special emphasis is given on the emerging and outbreak pathogen Crimean-Congo Haemorrhagic Fever virus (CCHFV) that can cause severe disease in humans. We discuss the efforts undertaken to better understand CCHF and the importance of integrating veterinary and human research for this pathogen. Furthermore, we consider the use of closely related nairoviruses to model human disease caused by CCHFV. We discuss intervention approaches with potential application for managing CCHFV spread, and how this concept may benefit both animal and human health.

Role of Zoo-Housed Animals in the Ecology of Ticks and Tick-Borne Pathogens-A Review

Ticks are ubiquitous ectoparasites, feeding on representatives of all classes of terrestrial vertebrates and transmitting numerous pathogens of high human and veterinary medical importance. Exotic animals kept in zoological gardens, ranches, wildlife parks or farms may play an important role in the ecology of ticks and tick-borne pathogens (TBPs), as they may serve as hosts for local tick species. Moreover, they can develop diseases of varying severity after being infected by TBPs, and theoretically, can thus serve as reservoirs, thereby further propagating TBPs in local ecosystems. The definite role of these animals in the tick-host-pathogen network remains poorly investigated. This review provides a summary of the information currently available regarding ticks and TBPs in connection to captive local and exotic wildlife, with an emphasis on zoo-housed species.