Lyme Disease Emergence after Invasion of the Blacklegged Tick, Ixodes scapularis, Ontario, Canada, 2010-2016.
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ABSTRACT:
SUBMITTER: Kulkarni MA
PROVIDER: S-EPMC6346472 | biostudies-literature |
REPOSITORIES: biostudies-literature
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Project description:The blacklegged tick, Ixodes scapularis, is established in several regions of Ontario, Canada, and continues to spread into new geographic areas across the province at a rapid rate. This poses a significant public health risk since I. scapularis transmits the Lyme disease-causing bacterium, Borrelia burgdorferi, and other pathogens of potential public health concern. The objective of this study was to develop species distribution models for I. scapularis and B. burgdorferi to predict and compare the potential distributions of the tick vector and the Lyme disease pathogen as well as the ecological factors most important for species establishment. Ticks were collected via tick dragging at 120 sites across southern, central, and eastern Ontario between 2015 and 2018 and tested for tick-borne pathogens. A maximum entropy (Maxent) approach was used to model the potential distributions of I. scapularis and B. burgdorferi. Two independent datasets derived from tick dragging at 25 new sites in 2019 and ticks submitted by the public to local health units between 2015 and 2017 were used to validate the predictive accuracy of the models. The model for I. scapularis showed high suitability for blacklegged ticks in eastern Ontario and some regions along the shorelines of the Great Lakes, and moderate suitability near Algonquin Provincial Park and the Georgian Bay with good predictive accuracy (tick dragging 2019: AUC = 0.898; ticks from public: AUC = 0.727). The model for B. burgdorferi showed a similar predicted distribution but was more constrained to eastern Ontario, particularly between Ottawa and Kingston, and along Lake Ontario, with similarly good predictive accuracy (tick dragging 2019: AUC = 0.958; ticks from public: AUC = 0.863. The ecological variables most important for predicting the distributions of I. scapularis and B. burgdorferi included elevation, distance to deciduous and coniferous forest, proportions of agricultural land, water, and infrastructure, mean summer/spring temperature, and cumulative annual degree days above 0°C. Our study presents a novel application of species distribution modelling for I. scapularis and B. burgdorferi in Ontario, Canada, and provides an up to date projection of their potential distributions for public health knowledge users.
| S-EPMC7485816 | biostudies-literature
Project description:We identified ticks submitted by the public from 2008 through 2012 in Ontario, Canada, and tested blacklegged ticks Ixodes scapularis for Borrelia burgdorferi and Anaplasma phagocytophilum. Among the 18 species of ticks identified, I. scapularis, Dermacentor variabilis, Ixodes cookei and Amblyomma americanum represented 98.1% of the 14,369 ticks submitted. Rates of blacklegged tick submission per 100,000 population were highest in Ontario's Eastern region; D. variabilis in Central West and Eastern regions; I. cookei in Eastern and South West regions; and A. americanum had a scattered distribution. Rates of blacklegged tick submission per 100,000 population were highest from children (0-9 years old) and older adults (55-74 years old). In two health units in the Eastern region (i.e., Leeds, Grenville & Lanark District and Kingston-Frontenac and Lennox & Addington), the rate of submission for engorged and B. burgdorferi-positive blacklegged ticks was 47× higher than the rest of Ontario. Rate of spread for blacklegged ticks was relatively faster and across a larger geographic area along the northern shore of Lake Ontario/St. Lawrence River, compared with slower spread from isolated populations along the northern shore of Lake Erie. The infection prevalence of B. burgdorferi in blacklegged ticks increased in Ontario over the study period from 8.4% in 2008 to 19.1% in 2012. The prevalence of B. burgdorferi-positive blacklegged ticks increased yearly during the surveillance period and, while increases were not uniform across all regions, increases were greatest in the Central West region, followed by Eastern and South West regions. The overall infection prevalence of A. phagocytophilum in blacklegged ticks was 0.3%. This study provides essential information on ticks of medical importance in Ontario, and identifies demographic and geographic areas for focused public education on the prevention of tick bites and tick-borne diseases.
| S-EPMC4149368 | biostudies-literature
Project description:Canadians face an emerging threat of Lyme disease due to the northward expansion of the tick vector, Ixodes scapularis. We evaluated the degree of I. scapularis population establishment and Borrelia burgdorferi occurrence in the city of Ottawa, Ontario, Canada from 2017-2019 using active surveillance at 28 sites. We used a field indicator tool developed by Clow et al. to determine the risk of I. scapularis establishment for each tick cohort at each site using the results of drag sampling. Based on results obtained with the field indicator tool, we assigned each site an ecological classification describing the pattern of tick colonization over two successive cohorts (cohort 1 was comprised of ticks collected in fall 2017 and spring 2018, and cohort 2 was collected in fall 2018 and spring 2019). Total annual site-specific I. scapularis density ranged from 0 to 16.3 ticks per person-hour. Sites with the highest density were located within the Greenbelt zone, in the suburban/rural areas in the western portion of the city of Ottawa, and along the Ottawa River; the lowest densities occurred at sites in the suburban/urban core. B. burgdorferi infection rates exhibited a similar spatial distribution pattern. Of the 23 sites for which data for two tick cohorts were available, 11 sites were classified as "high-stable", 4 were classified as "emerging", 2 were classified as "low-stable", and 6 were classified as "non-zero". B. burgdorferi-infected ticks were found at all high-stable sites, and at one emerging site. These findings suggest that high-stable sites pose a risk of Lyme disease exposure to the community as they have reproducing tick populations with consistent levels of B. burgdorferi infection. Continued surveillance for I. scapularis, B. burgdorferi, and range expansion of other tick species and emerging tick-borne pathogens is important to identify areas posing a high risk for human exposure to tick-borne pathogens in the face of ongoing climate change and urban expansion.
| S-EPMC7861446 | biostudies-literature
Project description:Lyme disease has emerged as a major health concern in Canada, where the etiological agent, Borrelia burgdorferi sensu lato (s.l.), a spirochetal bacterium, is typically spread by the bite of certain ticks. This study explores the presence of B. burgdorferi s.l. in blacklegged ticks, Ixodes scapularis, collected at Dundas, Ontario (a locality within the region of Hamilton-Wentworth). Using passive surveillance, veterinarians and pet groomers were asked to collect blacklegged ticks from dogs and cats with no history of travel. Additionally, I. scapularis specimens were submitted from local residents and collected by flagging. Overall, 12 (41%) of 29 blacklegged ticks were infected with B. burgdorferi s.l. Using polymerase chain reaction (PCR) and DNA sequencing, two borrelial amplicons were characterized as B. burgdorferi sensu stricto (s.s.), a genospecies pathogenic to humans and certain domestic animals. Notably, three different vertebrate hosts each had two engorged I. scapularis females removed on the same day and, likewise, one cat had three repeat occurrences of this tick species. These multiple infestations suggest that a population of I. scapularis may be established in this area. The local public health unit has been underreporting the presence of B. burgdorferi s.l.-infected I. scapularis in the area encompassing Dundas. Our findings raise concerns about the need to erect tick warning signs in parkland areas. Veterinarians, medical professionals, public health officials, and the general public must be vigilant that Lyme disease-carrying blacklegged ticks pose a public health risk in the Dundas area and the surrounding Hamilton-Wentworth region.
| S-EPMC4879763 | biostudies-literature
Project description:BackgroundThe emergence of vector-borne pathogens in novel geographic areas is regulated by the migration of their arthropod vectors. Blacklegged ticks (Ixodes scapularis) and the pathogens they vector, including the causative agents of Lyme disease, babesiosis and anaplasmosis, continue to grow in their population sizes and to expand in geographic range. Migration of this vector over the previous decades has been implicated as the cause of the re-emergence of the most prevalent infectious diseases in North America.MethodsWe systematically collected ticks from across New York State (hereafter referred to as New York) from 2004 to 2017 as part of routine tick-borne pathogen surveillance in the state. This time frame corresponds with an increase in range and incidence of tick-borne diseases within New York. We randomly sampled ticks from this collection to explore the evolutionary history and population dynamics of I. scapularis. We sequenced the mitochondrial genomes of each tick to characterize their current and historical spatial genetic structure and population growth using phylogeographic methods.ResultsWe sequenced whole mitochondrial genomes from 277 ticks collected across New York between 2004 and 2017. We found evidence of population genetic structure at a broad geographic scale due to differences in the relative abundance, but not the composition, of haplotypes among sampled ticks. Ticks were often most closely related to ticks from the same and nearby collection sites. The data indicate that both short- and long-range migration events shape the population dynamics of blacklegged ticks in New York.ConclusionsWe detailed the population dynamics of the blacklegged tick (Ixodes scapularis) in New York during a time frame in which tick-borne diseases were increasing in range and incidence. Migration of ticks occurred at both coarse and fine scales in the recent past despite evidence of limits to gene flow. Past and current tick population dynamics have implications for further range expansion as habitat suitability for ticks changes due to global climate change. Analyses of mitochondrial genome sequencing data will expound upon previously identified drivers of tick presence and abundance as well as identify additional drivers. These data provide a foundation on which to generate testable hypotheses on the drivers of tick population dynamics occurring at finer scales.
| S-EPMC9241328 | biostudies-literature
Project description:Dopamine (DA) is known to be the most potent activator of tick salivary secretion, which is an essential component of successful tick feeding. We examined the quantitative changes of catecholamines using a method coupling high-pressure liquid chromatography with electrochemical detection (HPLC-ECD). We also investigated the levels of catecholamines conjugated to other molecules utilising appropriate methods to hydrolyse the conjugates. Three different biological samples, salivary glands, synganglia, ovaries and haemolymph were compared, and the largest quantity of DA was detected in salivary gland extracts (up to ?100pg/tick), supporting the hypothesis that autocrine/paracrine dopamine activates salivary secretion. Quantitative changes of catecholamines in the salivary glands over the entire blood feeding duration were examined. The amount of dopamine in the salivary glands increased until the day 5 of feeding, at which the rapid engorgement phase began. We also detected a small but significant amount of norepinephrine in the salivary glands. Interestingly, saliva collected after induction of salivary secretion by the cholinergic agonist pilocarpine contained a large amount of DA sulphate with a trace amount of DA, suggesting a potential biological role of DA sulphate in tick saliva.
| S-EPMC4006075 | biostudies-literature
Project description:We obtained a rickettsial isolate from the ovaries of the blacklegged tick, Ixodes scapularis. The isolate (ISO7(T)) was grown in the Ixodes ricinus embryonic cell line IRE11. We characterized the isolate by transmission electron microscopy and gene sequencing. Phylogenetic analysis of 11 housekeeping genes demonstrated that the isolate fulfils the criteria to be classified as a representative of a novel rickettsial species closely related to 'Rickettsia monacensis'. These rickettsiae form a clade separate from other species of rickettsiae. Gene sequences indicated that several genes important in rickettsial motility, invasiveness and temperature adaptation were mutated (e.g. sca2, rickA, hsp22, pldA and htrA). We propose the name Rickettsia buchneri sp. nov. for this bacterium that infects the ovaries of the tick I. scapularis to acknowledge the pioneering contributions of Professor Paul Buchner (1886-1978) to research on bacterial symbionts. The type strain of R. buchneri sp. nov. is strain ISO-7(T) ( = DSM 29016(T) = ATCC VR-1814(T)).
| S-EPMC4365292 | biostudies-literature
Project description:Ticks transmit more pathogens to humans and animals than any other arthropod. We describe the 2.1 Gbp nuclear genome of the tick, Ixodes scapularis (Say), which vectors pathogens that cause Lyme disease, human granulocytic anaplasmosis, babesiosis and other diseases. The large genome reflects accumulation of repetitive DNA, new lineages of retro-transposons, and gene architecture patterns resembling ancient metazoans rather than pancrustaceans. Annotation of scaffolds representing ∼57% of the genome, reveals 20,486 protein-coding genes and expansions of gene families associated with tick-host interactions. We report insights from genome analyses into parasitic processes unique to ticks, including host 'questing', prolonged feeding, cuticle synthesis, blood meal concentration, novel methods of haemoglobin digestion, haem detoxification, vitellogenesis and prolonged off-host survival. We identify proteins associated with the agent of human granulocytic anaplasmosis, an emerging disease, and the encephalitis-causing Langat virus, and a population structure correlated to life-history traits and transmission of the Lyme disease agent.
| S-EPMC4748124 | biostudies-literature
Project description:Salivary secretion is crucial for successful tick feeding, and it is the mediator of pathogen transmission. Salivation functions to inhibit various components of the host immune system and remove excess water and ions during the ingestion of large blood meals. Control of salivary glands involves autocrine/paracrine dopamine, which is the most potent inducer of tick salivation. Previously, we reported the presence of two dopamine receptors in the salivary glands of the blacklegged tick (Ixodes scapularis): dopamine receptor (D1) and invertebrate specific D1-like dopamine receptor (InvD1L). Here, we investigated the different physiological roles of the dopamine receptors in tick salivary glands by using pharmacological tools that discriminate between the two distinct receptors. Heterologous expressions followed by reporter assays of the dopamine receptors identified receptor-specific antagonists and agonists. These pharmacological tools were further used to discriminate the physiological role of each receptor by using in vitro assays: measuring salivary secretions of isolated salivary glands and monitoring dynamic changes in the size of individual salivary gland acini. We propose that the D1 receptor acts on salivary gland acini epithelial cells for inward fluid transport. InvD1L controls (or modulates) each acinus for expelling saliva from the acini to the salivary ducts, presumably through the actions of myoepithelial cells and valves for pumping/gating. We conclude that dopamine acts on the D1 and the InvD1L receptors and leads different physiological actions to orchestrate tick salivary secretion.
| S-EPMC4198381 | biostudies-literature
Project description:Tick salivary glands play critical roles in maintaining water balance for survival, as they eliminate excess water and ions during blood feeding on hosts. In the long duration of fasting in the off-host period, ticks secrete hygroscopic saliva into the mouth cavity to uptake atmospheric water vapor. Type I acini of tick salivary glands are speculated to be involved in secretion of hygroscopic saliva based on ultrastructure studies. However, we recently proposed that type I acini play a role in resorption of water/ions from the primary saliva produced by other salivary acini (i.e., types II and III) during the tick blood feeding phase. In this study, we tested the function of type I acini in unfed female Ixodes scapularis. The route of ingested water was tracked after forced feeding of water with fluorescent dye rhodamine123. We found that type-I acini of the salivary glands, but not type II and III, are responsible for water uptake. In addition, the ingestion of water through the midgut was also observed. Injection or feeding of ouabain, a Na/K-ATPase inhibitor, suppressed water absorption in type I acini. When I. scapularis was offered a droplet of water, ticks rarely imbibed water directly (5%), while some approached the water droplet to use the high humidity formed in the vicinity of the droplet (23%). We conclude that during both on- and off-host stages, type I acini in salivary glands of female Ixodes scapularis absorb water and ions.
| S-EPMC5669254 | biostudies-literature