Prevalence of Borrelia burgdorferi and Borrelia miyamotoi in questing Ixodes ricinus ticks from four sites in the UK

Tick hazard in the South Downs National Park (UK): species, distribution, key locations for future interventions, site density, habitats

Background

South Downs National Park (SDNP) is UK's most visited National Park, and a focus of tick-borne Lyme disease. The first presumed UK autochthonous cases of tick-borne encephalitis and babesiosis were recorded in 2019-20. SDNP aims to conserve wildlife and encourage recreation, so interventions are needed that reduce hazard without negatively affecting ecosystem health. To be successful these require knowledge of site hazards.

Methods

British Deer Society members submitted ticks removed from deer. Key potential intervention sites were selected and six 50 m2 transects drag-sampled per site (mostly twice yearly for 2 years). Ticks were identified in-lab (sex, life stage, species), hazard measured as tick presence, density of ticks (all life stages, DOT), and density of nymphs (DON). Sites and habitat types were analysed for association with hazard. Distribution was mapped by combining our results with records from five other sources.

Results

A total of 87 Ixodes ricinus (all but one adults, 82% F) were removed from 14 deer (10 Dama dama; three Capreolus capreolus; one not recorded; tick burden, 1-35) at 12 locations (commonly woodland). Five key potential intervention sites were identified and drag-sampled 2015-16, collecting 623 ticks (238 on-transects): 53.8% nymphs, 42.5% larvae, 3.7% adults (13 M, 10 F). Ticks were present on-transects at all sites: I. ricinus at three (The Mens (TM); Queen Elizabeth Country Park (QECP); Cowdray Estate (CE)), Haemaphysalis punctata at two (Seven Sisters Country Park (SSCP); Ditchling Beacon Nature Reserve (DBNR)). TM had the highest DOT at 30/300 m2 (DON = 30/300 m2), followed by QECP 22/300 m2 (12/300 m2), CE 8/300 m2 (6/300 m2), and SSCP 1/300 m2 (1/300 m2). For I. ricinus, nymphs predominated in spring, larvae in the second half of summer and early autumn. The overall ranking of site hazard held for DON and DOT from both seasonal sampling periods. DBNR was sampled 2016 only (one adult H. punctata collected). Woodland had significantly greater hazard than downland, but ticks were present at all downland sites. I. ricinus has been identified in 33/37 of SDNPs 10 km2 grid squares, Ixodes hexagonus 10/37, H. punctata 7/37, Dermacentor reticulatus 1/37.

Conclusions

Mapping shows tick hazard broadly distributed across SDNP. I. ricinus was most common, but H. punctata's seeming range expansion is concerning. Recommendations: management of small heavily visited high hazard plots (QECP); post-visit precaution signage (all sites); repellent impregnated clothing for deerstalkers; flock trials to control H. punctata (SSCP, DBNR). Further research at TM may contribute to knowledge on ecological dynamics underlying infection density and predator re-introduction/protection as public health interventions. Ecological research on H. punctata would aid control. SDNP Authority is ideally placed to link and champion policies to reduce hazard, whilst avoiding or reducing conflict between public health and ecosystem health.

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

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

Detection, identification and genotyping of Borrelia spp. in ticks of Coastal-Karst and Littoral-Inner Carniola regions in Slovenia

The density and spread of tick vector species have increased throughout Europe in the last 30 years, leading to an increase of Lyme borreliosis cases, including in Slovenia. The aim of this study was to isolate Borrelia strains and determine the prevalence of B. burgdorferi sensu lato and B. miyamotoi in adults of Ixodes ricinus (Linnaeus) collected in 2019 in the two regions of the country (Coastal-Karst and Littoral-Inner Carniola) by cultivation and PCR. We isolated B. burgdorferi s.l. by culture method in 28/559 (5%) ticks from both regions. Culture-negative samples (531/559, i.e., 95%) were additionally tested by real-time PCR. In 155/531 (29.2%) PCR-positive samples, a fragment of flaB or glpQ was amplified and further sequenced to identify species of the Borrelia. Using both methods, cultivation and PCR, Borrelia spp. prevalence was 32.7% in the Coastal-Karst region and 33.0% in the Littoral-Inner Carniola region. Genotyping of the Borrelia spp. isolates revealed that 17/28 (60%) were B. garinii subtype Mlg2. Of all tick samples tested for B. miyamotoi 8/398 (2%) were PCR positive. Based on previous studies in these regions, we had expected more ticks to be infected with B. afzelii, but genotyping revealed that B. garinii was the most abundant.

The Surveillance of Borrelia Species in Camelus dromedarius and Associated Ticks: The First Detection of Borrelia miyamotoi in Egypt

Tick-borne diseases (TBDs) are emerging and re-emerging infections that have a worldwide impact on human and animal health. Lyme borreliosis (LB) is a severe zoonotic disease caused by the spirochete Borrelia burgdorferi sensu lato (s.l.) transmitted to humans by the bite of infected Ixodes ticks. Borrelia miyamotoi is a spirochete that causes relapsing fever (RF) and is genetically related to Borrelia burgdorferi s.l. However, there have been no reports of B. miyamotoi in Egypt, and the data on LB in camels is scarce. Thus, the present study was conducted to screen and genetically identify Borrelia spp. and B. miyamotoi in Egyptian camels and associated ticks using polymerase chain reaction (PCR).

METHODS

A total of 133 blood samples and 1596 adult hard ticks were collected from Camelus dromedaries at Cairo and Giza slaughterhouses in Egypt. Tick species were identified by examining their morphology and sequencing the cytochrome C oxidase subunit 1 (cox1) gene. Borrelia spp. was detected using nested PCR on the IGS (16S-23S) gene, and positive samples were genotyped using 16S rRNA and glpQ spp. genes specific for Borrelia burgdorferi and Borrelia miyamotoi, respectively. The positive PCR products were sequenced and analyzed by phylogenetic tree.

RESULTS

Analysis of the cox1 gene sequence revealed that the adult ticks belonged to three genera; Hyalomma (H), Amblyomma (Am), and Rhipicephalus (R), as well as 12 species, including H. dromedarii, H. marginatum, H. excavatum, H. anatolicum, R. annulatus, R. pulchellus, Am. testudinarium, Am. hebraeum, Am. lipidium, Am. variegatum, Am. cohaerens and Am. gemma. Borrelia spp. was found in 8.3% (11/133) of the camel blood samples and 1.3% (21/1596) of the ticks, respectively. Sequencing of the IGS (16S-23S) gene found that B. afzelii, detected from H. dromedarii and H. marginatum, and B. crocidurae, which belongs to the RF group, was detected from one blood sample. B. burgdorferi and B. miyamotoi were discovered in the blood samples and tick species. Phylogenetic analysis of the glpQ gene showed that the B. miyamotoi in this study was of the Asian and European types.

CONCLUSIONS

These results suggest that the camels can be infected by Lyme borrelia and other Borrelia bacteria species. This study also provides the first insight into the presence of Borrelia miyamotoi and B. afzelii DNA in camels and associated ticks in Egypt.

Predicting the current and future risk of ticks on livestock farms in Britain using random forest models

The most abundant tick species in northern Europe, Ixodes ricinus, transmits a range of pathogens that cause disease in livestock. As I. ricinus distribution is influenced by climate, tick-borne disease risk is expected to change in the future. The aims of this work were to build a spatial model to predict current and future risk of ticks on livestock farms across Britain. Variables relating both to tick hazard and livestock exposure were included, to capture a niche which may be missed by broader scale models. A random forest machine learning model was used due to its ability to cope with correlated variables and interactions. Data on tick presence and absence on sheep and cattle farms was obtained from a retrospective questionnaire survey of 926 farmers. The ROC of the final model was 0.80. The model outputs matched observed patterns of tick distribution, with areas of highest tick risk in southwest and northwest England, Wales, and west Scotland. Overall, the probability of tick presence on livestock farms was predicted to increase by 5-7 % across Britain under future climate scenarios. The predicted increase is greater at higher altitudes and latitudes, further increasing the risk of tick-borne disease on farms in these areas.

Spatial and temporal heterogeneity of the density of Borrelia burgdorferi-infected Ixodes ricinus ticks across a landscape: A 5-year study in southern England

The density of Borrelia burgdorferi-infected Ixodes ricinus nymphs (DIN) was investigated during 2013-2017 across a Lyme disease-endemic landscape in southern England. The density of nymphs (DON), nymph infection prevalence (NIP), and DIN varied across five different natural habitats, with the highest DIN in woodland edge and high biodiversity woodlands. DIN was significantly lower in scrub grassland compared to the woodland edge, with low DON and no evidence of infection in ticks in non-scrub grassland. Over the 5 years, DON, NIP and DIN were comparable within habitats, except in 2014, with NIP varying three-fold and DIN significantly lower compared to 2015-2017. Borrelia garinii was most common, with bird-associated Borrelia (B. garinii/valaisiana) accounting for ~70% of all typed sequences. Borrelia burgdorferi sensu stricto was more common than B. afzelii. Borrelia afzelii was more common in scrub grassland than woodland and absent in some years. The possible impact of scrub on grazed grassland, management of ecotonal woodland margins with public access, and the possible role of birds/gamebirds impacting NIP are discussed. Mean NIP was 7.6%, highlighting the potential risk posed by B. burgdorferi in this endemic area. There is a need for continued research to understand its complex ecology and identify strategies for minimizing risk to public health, through habitat/game management and public awareness.

Detection of Borrelia and Babesia species in Haemaphysalis punctata ticks sampled in Southern England

The distribution and population size of the red sheep tick (Haemaphysalis punctata) are increasing in Northern Europe, and in the United Kingdom reports of human biting by this species have increased in recent years. To assess the risk of tick-borne disease (TBD) transmission to humans and livestock by H. punctata, ticks sampled from sites in Southern England were screened using PCR for either Borrelia species or piroplasms over a three year period, 2018-2020. A total of 302 H. punctata were collected from eight locations. From these, two Babesia species associated with TBD infections in livestock, Babesia major and Babesia motasi, and the human pathogen Borrelia miyamotoi were detected, predominantly from a single location in Sussex. Consequently, the range expansion of this tick across Southern England may impact public and livestock health.

Urban woodland habitat is important for tick presence and density in a city in England

Urban green spaces provide an opportunity for contact between members of the public and ticks infected with pathogens. Understanding tick distribution within these areas and the drivers for increased tick density or Borrelia infection are important from a risk management perspective. This study aimed to generate data on tick presence, nymph density and Borrelia infection across a range of urban green space habitats, in order to identify those that may potentially present a higher risk of Lyme borreliosis to members of the public. Several sites were visited across the English city of Bath during 2015 and 2016. Tick presence was confirmed in all habitats surveyed, with increased likelihood in woodland and woodland edge. Highest nymph densities were also reported in these habitats, along with grassland during one of the sampling years. Adult ticks were more likely to be infected compared to nymphs, and the highest densities of infected nymphs were associated with woodland edge habitat. In addition to Lyme borreliosis causing Borrelia genospecies, Borrelia miyamotoi was also detected at several sites. This study adds to the growing evidence that urban green space habitats present a public health risk from tick bites, and this has implications for many policy areas including health and wellbeing, climate adaptation and urban green space planning.

A nationwide study on Borrelia burgdorferi s.l. infection rates in questing Ixodes ricinus: a six-year snapshot study in protected recreational areas in England and Wales

Understanding the variation in Borrelia burgdorferi s.l. infection rates in Ixodes ricinus ticks is important for assessing the potential for Lyme borreliosis transmission. This study aimed to investigate infection rates of B. burgdorferi s.l. bacteria in I. ricinus across 24 field sites in England and Wales, focussing on protected recreational areas in National Parks (NPs) and Areas of Outstanding Natural Beauty (AONBs), to provide comparable data across multiple years to assess spatio-temporal changes in B. burgdorferi s.l. infection. Working with park rangers, questing ticks were collected each spring from 2014 to 2019. A subset of ticks, 4104 nymphs, were analysed using a pan-Borrelia qPCR assay, as well as a Borrelia miyamotoi-specific qPCR, and sequenced to determine Borrelia burgdorferi s.l. genospecies. Site-specific B. burgdorferi s.l. infection rates in I. ricinus nymphs varied from 0% to 24%, with overall infection rates ranging from 2.5% to 5.1% across the years. Genospecies composition of sequenced samples was 62.5% B. garinii, 20.3% B. valaisiana and 17.2% B. afzelii. Borrelia miyamotoi was detected in 0.2% of ticks. This study increases our knowledge on B. burgdorferi s.l.. infection in areas used by the public for outdoor activity across England and Wales, highlighting the spatial and temporal variability which can impact the changing risk to humans from infected tick bites.

Bacterial Pathogens and Symbionts Harboured by Ixodes ricinus Ticks Parasitising Red Squirrels in the United Kingdom

Red squirrels (Sciurus vulgaris) are native to most of Eurasia; in much of the United Kingdom, they have been supplanted by the non-native grey squirrel, and are considered an endangered species. Very little is known about the range of tick-borne pathogens to which UK red squirrels are exposed. As part of trap-and-release surveys examining prevalence of Mycobacterium spp. in red squirrel populations on two UK islands, Ixodes ricinus ticks were removed from squirrels and PCR screened for Borrelia spp., intracellular arthropod-borne bacteria and the parasitic wasp Ixodiphagus hookeri. At both sites, the most commonly encountered tick-transmitted bacterium was Borrelia burgdorferi sensu lato (overall minimum prevalence 12.7%), followed by Anaplasma phagocytophilum (overall minimum prevalence 1.6%). Single ticks infected with Spiroplasma were found at both sites, and single ticks infected with Borrelia miyamotoi or an Ehrlichia sp. at one site. Ticks harbouring Wolbachia (overall minimum prevalence 15.2%) were all positive for I. hookeri. Our study shows that UK red squirrels are potentially exposed to a variety of bacterial pathogens via feeding ticks. The effects on the health and survival of this already vulnerable wildlife species are unknown, and further studies are needed to evaluate the threat posed to red squirrels by Borrelia and other tick-borne pathogens.

Borrelia miyamotoi-An Emerging Human Tick-Borne Pathogen in Europe

Borrelia miyamotoi is classified as a relapsing fever spirochete. Although B. miyamotoi is genetically and ecologically distinct from Borrelia burgdorferi sensu lato, both microorganisms are transmitted by the same Ixodes tick species. B. miyamotoi was detected in I. persulcatus ticks in 1994 in Japan. A phylogenetic analysis based on selected sequences of B. miyamotoi genome revealed genetic differences between isolates from Asia, North America, and Europe, which are clearly separated into three genotypes. Symptomatic human cases of Borrelia miyamotoi disease (BMD) were first reported in 2011 in Russia and then in North America, Europe, and Asia. The most common clinical manifestation of BMD is fever with flu-like symptoms. Several differences in rare symptoms (thrombocytopenia, monocytosis, cerebrospinal fluid pleocytosis, or symptoms related to the central nervous system) have been noted among cases caused by Asian, European, and American types of B. miyamotoi. BMD should be considered in the diagnosis of patients after tick bites, particularly with meningoencephalitis, without anti-Borrelia antibodies in the cerebrospinal fluid. This review describes the biology, ecology, and potential of B. miyamotoi as a tick-borne pathogen of public health concern, with particular emphasis on Europe.

Borrelia miyamotoi: 43 Cases Diagnosed in France by Real-Time PCR in Patients With Persistent Polymorphic Signs and Symptoms

Background:Borrelia species are divided into three groups depending on the induced disease and the tick vector. Borrelia miyamotoi is a relapsing fever Borrelia but can induce symptoms related to Lyme disease. Discovered in 1995, it is found in ticks around the world. In France, this species of Borrelia has been isolated in ticks and rodents, but was not yet observed in humans.

Objective: The aim of the study was to look for B. miyamotoi in symptomatic patients.

Methods: Real-time PCR was performed on 824 blood samples from patients presenting symptoms of persistent polymorphic syndrome possibly due to tick bite, a syndrome recognized by the French Authority for Health, which is close to the post-treatment Lyme disease syndrome. PCR was also performed on 24 healthy control persons. The primers were specifically designed for this particular species of Borrelia. The sequence of interest of 94 bp is located on the glpQ gene. Sequencing of amplification products, randomly chosen, confirmed the amplification specificity. To better investigate cases, a clinical questionnaire was sent to the patients PCR-positive for B. miyamotoi and to their physician.

Results: This search revealed a positive PCR for B. miyamotoi in the blood from 43 patients out of 824 (5.22%). PCR was negative in all control persons. A clinical chart was obtained from 31 of the 43 patients. A history of erythema migrans was reported in five of these 31 patients (16%). All patients complained about fatigue, joint pain and neuro-cognitive disorders. Some patients complained about respiratory problems (chest tightness and/or lack of air in 41.9%). Episodes of relapsing fever were reported by 11 of the 31 patients (35.5%). Chilliness, hot flushes and/or sweats were reported by around half of the patients. B. miyamotoi may not cross-react with B. burgdorferi serology.

Conclusion: This study is the first to detect B. miyamotoi in human blood in France. This series of human B. miyamotoi infection is the largest in patients with long term persistent syndrome. Our data suggest that this infection may be persistent, even on the long term.

Ticks on the Channel Islands and implications for public health

The Channel Islands are British Crown dependencies located in the English Channel to the west of the Normandy coast in northern France. Whilst there have been studies investigating tick occurrence and distribution in different habitats on the mainland of the UK and in France, the Channel Islands have been relatively understudied. As such, little is known about whether the sheep tick, Ixodes ricinus, is present, and whether there is a potential risk of Lyme borreliosis on the Channel Islands. To ascertain the presence of I. ricinus on the three largest islands in the archipelago: Jersey, Guernsey and Alderney, surveys of ticks questing in the vegetation and ticks feeding on hosts were undertaken during April and May 2016. Across all three islands, the highest numbers of ticks were found in woodland habitats. Ixodes ricinus was the predominant questing tick species found on Jersey, and Ixodes ventalloi the most common questing tick species on Alderney and Guernsey, with little or no evidence of questing I. ricinus on either island. During field studies on small mammals, I. ricinus was the predominant tick species feeding on Jersey bank voles (Myodes glareolus caesarius), with Ixodes hexagonus the most common species infesting hedgehogs on Guernsey. We propose that the greater diversity of small mammals on Jersey may be important in supporting immature stages of I. ricinus, in contrast to Guernsey and Alderney. Morphological identification of tick species was confirmed by PCR sequencing based on amplification of the cytochrome c oxidase subunit one (cox1) gene (COI DNA barcoding). To date, there have been few records of human tick bites in the Channel Islands, suggesting that the current risk from tick-borne disease may be low, but continued reporting of any human tick bites, along with reporting of cases of Lyme borreliosis will be important for continued assessment of the impact of tick-borne diseases in the Channel Islands.