Epidemiology of ticks submitted from human hosts in Alberta, Canada (2000-2019).

ABSTRACTThe geographic range and occurrence of tick species is dynamic. This has important public health implications due to important tick species that can transmit pathogens. This study presents a retrospective review of tick genera recovered from humans and submitted for identification in Alberta, Canada, over a 19-year period. The total number of ticks and proportion of genera were analyzed over time. Molecular testing for a number of pathogens associated with Ixodes scapularis and I. pacificus was conducted. A total of 2,358 ticks were submitted between 2000 and 2019, with 98.6% being acquired in Alberta. The number of ticks submitted increased significantly over time (p < 0.0001). Dermacentor ticks were the most abundant genus, followed by Ixodes and Amblyomma. There was a significant decrease in the proportion of Dermacentor ticks between 2013 and 2019 (p = 0.02), with a corresponding increase in the proportion of Ixodes ticks over the same time (p = 0.04). No statistically significant change in seasonality was identified. Borrelia burgdorferi was detected in 8/76 (10.5%; 95% CI 5.4-19.4%) of all I. scapularis and I. pacificus ticks submitted. This translated to a B. burgdorferi positivity of 0.35% (95% CI 0.15-0.68%) among all ticks received. Dermacentor species (especially D. andersoni) remains the most common tick feeding on humans in Alberta. Small numbers of vector species (including I. scapularis/pacificus) are encountered annually over widely separated geographic areas in the province. The risk of exposure to tick-borne pathogens (e.g. Lyme disease) in Alberta remains low.

Occurrence of juvenile Dermacentor reticulatus ticks in three regions in Poland: the final evidence of the conquest.

BACKGROUND: Two populations of Dermacentor reticulatus ticks (Western and Eastern) in Poland are among the most dynamic tick populations in Central Europe. Expansion and settlement of ticks in new localizations depend on the presence of suitable hosts, for both adult and juvenile ticks. METHODS: The current study was planned to complement our previous studies on questing adult ticks and was focused on a collection of juvenile D. reticulatus ticks from rodents from three regions in Poland, defined by the presence/absence of adult ticks (regions of the Western and Eastern tick population and the gap area between them) to confirm the existence of stable populations. Rodent trapping was conducted in open habitats (fallow lands, wasteland and submerged meadows) in 2016-2018 in June, July and/or August to encompass seasonal peaks of larvae and nymph activity. RESULTS: Altogether, three tick species were collected, 2866 D. reticulatus, 2141 Ixodes ricinus and 427 Haemaphysalis concinna. Dermacentor reticulatus was the most common (72.3%) and abundant (mean 17.94 ± 2.62 ticks/rodent) tick species on rodents from the Eastern region; in the Western region infestation of rodents was only 6.8%. Ixodes ricinus was found in all three regions and was the only tick species collected from rodents from the gap area. Haemaphysalis concinna was noted only in the Western region. The highest infestation of juvenile D. reticulatus was recorded on voles (Myodes and Microtus spp.), infestation of I. ricinus was the highest on Apodemus mice, and the majority of H. concinna ticks were collected from root voles Alexandromys oeconomus. CONCLUSIONS: Our study confirmed a stable population of D. reticulatus in Eastern and Central Poland and a lower prevalence and mean abundance of this tick species among rodents from the Western region. A lack of juvenile D. reticulatus on rodents in Niewiadów confirmed the existence of the gap area, free of D. reticulatus ticks.

Integrative Taxonomy of Dermacentor variabilis (Ixodida: Ixodidae) with Description of a New Species, Dermacentor similis n. sp.

Dermacentor variabilis is the most widely distributed three-host tick in North America, and transmits a variety of pathogens. Within the United States, this species has a discontinuous distribution, widespread east of the Rocky Mountains and with a few populations west of the Rockies. Phylogenetic evidence based on individual markers or relatively small data sets has suggested that populations at both sides of this geographic barrier may correspond to two different species. In this study, we further explore this hypothesis using an integrative taxonomy framework. Both molecular (mitochondrial and nuclear markers) and morphological analyses of specimens collected from central-eastern and western states were performed to explore species delimitation in this taxon. Results from these analyses were consistent, and provide strong evidence that D. variabilis actually corresponds to two species. Herein, the western populations are described as a new species, Dermacentor similis n. sp. The usefulness of integrative taxonomy in the context of species delimitation is also discussed.

Reinstatement of Dermacentor tricuspis (Schulze, 1933) n. comb., n. stat. (Acari: Ixodidae) as a valid species, synonymization of D. atrosignatus Neumann, 1906 and description of a new species from Indonesia, Malaysia and Thailand.

Re-examination of the holotype of Dermacentor atrosignatus Neumann, 1906 (Acari: Ixodidae) stored in the Natural History Museum (London, UK) revealed that this taxon is identical with D. auratus Supino, 1897 and should be treated as a junior synonym of the latter species. A correct name for the distinct species previously identified as D. atrosignatus Neumann, 1906 sensu Wassef & Hoogstraal, 1984 should be D. tricuspis (Schulze, 1933) n. comb., n. stat. Adults of D. tricuspis are redescribed here. Re-examination of extensive holdings of Oriental Dermacentor Koch, 1844 ticks stored in the United States National Tick Collection revealed that a morphologically distinct new species of this genus, namely D. falsosteini D. Apanaskevich, M. Apanaskevich & Nooma n. sp. should be recognized. Adults of D. tricuspis and D. falsosteini n. sp. can be distinguished from other species of Oriental Dermacentor and each other by the colour pattern of the conscutum and scutum, the pattern of punctations on the pseudoscutum and scutum, the shape of female genital structures and spurs on coxa I. Dermacentor tricuspis is recorded from Indonesia, Malaysia, the Philippines and Thailand where the adults were mostly collected from various species of wild pigs (Artiodactyla: Suidae) and vegetation; few adults were available from other mammals (Artiodactyla: Bovidae; Carnivora: Canidae, Felidae, Ursidae; Pholidota: Manidae), as well as humans and reptiles (Squamata: Elapidae, Varanidae). One male was reared from a nymph collected on a rodent (Rodentia: Muridae). Dermacentor falsosteini n. sp. is found in Indonesia, Malaysia and Thailand where the adults were collected from bearded pig, Sus barbatus Müller, wild boar, S. scrofa Linnaeus, unidentified wild pig, Sus sp. (Artiodactyla: Suidae), Malayan tapir, Tapirus indicus Desmarest (Perissodactyla: Tapiridae), human and vegetation.

Genetic diversity analysis of Dermacentor nuttalli within Inner Mongolia, China.

BACKGROUND: Ticks (Arthropoda, Ixodida), after mosquitoes, are the second most prevalent vector of infectious diseases. They are responsible for spreading a multitude of pathogens and threatening the health and welfare of animals and human beings. However, given the history of tick-borne pathogen infections in the Inner Mongolia Autonomous Region of China, surprisingly, neither the genetic diversity nor the spatial distribution of haplotypes within ticks has been studied. METHODS: We characterized the haplotype distribution of Dermacentor nuttalli in four main pastoral areas of the Inner Mongolia Autonomous Region, by sampling 109 individuals (recovered from sheep) in April-August 2019. The 16S rRNA gene, cytochrome c oxidase subunit I (COI), and the internal transcribed spacer 2 region (ITS2) were amplified and sequenced from extracted DNA. RESULTS: Twenty-six haplotypes were identified using 16S rRNA sequences, 57 haplotypes were identified with COI sequences, and 75 haplotypes were identified with ITS2 sequences. Among the three genes, total haplotype diversity was greater than 0.7, while total nucleotide diversity was greater than 0.06. Neutrality tests revealed a significantly negative Tajima's D result, while Fu's Fs was not significantly positive. Fixation index values (FST) indicated that the degree of genetic differentiation among some sampled populations was small, while for others it was moderate. Analysis of molecular variance (AMOVA) revealed that the variation within populations was greater than that among populations. The mismatch analysis of D. nuttalli exhibited double peaks. CONCLUSION: The genetic diversity of D. nuttalli populations in our region can likely adapt to different geographical environments, thereby leading to genetic diversity, and creating genetic differentiation among different populations. However, genetic differentiation is cryptic and does not form a pedigree geographical structure.

Scalp eschar and neck lymphadenopathy by Rickettsia slovaca after Dermacentor marginatus tick bite case report: multidisciplinary approach to a tick-borne disease.

BACKGROUND: Scalp Eschar and Neck LymphAdenopathy after Tick bite is a zoonotic non-pathogen-specific disease most commonly due to Rickettsia slovaca and Rickettsia raoultii. Diagnosis is mostly based only on epidemiological and clinical findings, without serological or molecular corroboration. We presented a clinical case in which diagnosis was supported by entomological identification and by R. slovaca DNA amplifications from the tick vector. CASE PRESENTATION: A 6-year-old child presented with asthenia, scalp eschar and supraclavicular and lateral-cervical lymphadenopathy. Scalp Eschar and Neck LymphAdenopathy After Tick bite syndrome following a Dermacentor marginatus bite was diagnosed. Serological test on serum revealed an IgG titer of 1:1024 against spotted fever group rickettsiae, polymerase chain reaction assays on tick identified Rickettsia slovaca. Patient was successfully treated with doxycycline for 10 days. CONCLUSIONS: A multidisciplinary approach including epidemiological information, clinical evaluations, entomological identification and molecular investigations on tick, enabled proper diagnosis and therapy.

Detection of Dermacentor andersoni (Acari: Ixodidae) in Brazil on a Human Traveler Returning from the United States.

Only one previous record of an exotic tick on a Brazilian traveler has been reported. Here, we report the detection of Dermacentor andersoni (Stiles) in Brazil while attached to a human traveler returning from the United States. This report is the fifth record of D. andersoni as an exotic tick, and the second record of an exotic tick on a South American traveler.

Description of a new species of Dermacentor Koch, 1844 (Acari: Ixodidae) from the mountains of Laos and Thailand.

Dermacentor pasteuri n. sp. (Acari: Ixodidae) is described based on adults ex wild boar and vegetation from Laos and Thailand. Adults of D. pasteuri n. sp. are similar to those of D. compactus Neumann, 1901, but can be distinguished by the shape of conscutum in the male, development of dorsal cornua in the female, size and shape of spurs on coxae and coloration of leg segments in both sexes.

Tick burden on European roe deer (Capreolus capreolus) from Saxony, Germany, and detection of tick-borne encephalitis virus in attached ticks.

Southern Germany is known as tick-borne encephalitis (TBE) risk area; however, the north of the country is almost free of human TBE cases. Due to its location in the transition zone between TBE risk areas and areas with only sporadic cases, Saxony is of importance in the surveillance of TBE. Roe deer (Capreolus capreolus), showing high seroprevalence of TBE virus (TBEV) antibodies, are considered to be sentinels for TBE risk assessment. Thus, roe deer could be used as indicators helping to better understand the focality of the TBEV in nature and as a possible source to isolate TBEV. Therefore, the aims of this study were to examine roe deer coats for the presence of ticks to establish the tick burden and to detect the TBEV in attached ticks. One hundred thirty-four roe deer coats were provided by hunters from the Hunting Association in Saxony (August 2017-January 2019). The coats were frozen at - 80 °C and after de-freezing examined on both sides-inside and outside. Attached and nonattached ticks were collected, morphologically identified and tested using real-time RT-PCR for the presence of TBEV. In total, 1279 ticks were found on 48 coats. The predominant species was Ixodes ricinus (99.76%; n = 1276). Three remaining specimens were Ixodes spp. (0.16%, 1 female and 1 nymph) and Dermacentor reticulatus (0.08%, 1 male). The average infestation rate was 26.7 (SD = 69.5), with maximum of 439 ticks per animal. Females were the dominant life stage of ticks (n = 536; 42%), followed by nymphs (n = 397; n = 31.1%), males (n = 175; 13.7%), and larvae (n = 168; 13.2%). Only half of collected ticks were attached (n = 662; 51.8%). TBEV was detected only in one tick out of 1279 tested ticks. It was a female infesting a roe deer from Saxon Switzerland-East Ore Mountain. The results show that the method used in this study is not sufficient as a sentinel marker to predict TBEV spreading in nature. Although previous studies demonstrated the usefulness of serological testing of roe deer in order to trace TBE-endemic regions, using ticks attached to them to get virus isolates is not productive.

Description and characterization of questing hard tick, Dermacentor steini (Acari: Ixodidae) in Malaysia based on phenotypic and genotypic traits.

Identifying certain species of Dermacentor ticks in Malaysia is challenging as there is no comprehensive work on their systematics and lack of specific taxonomic keys. In this study, we described and characterized D. steini ticks collected from a forest reserve in the vicinity of the Forest Research Institute of Malaysia using integrated phenotypic and genotypic traits. In total two males and three females of questing D. steini ticks were morphologically identified using specific illustrated taxonomic keys based on their special characters. Further confirmation and characterization of the tick species were then examined using PCR, followed by sequencing partial mitochondrial 16S rDNA gene (mt-rrs). Clustering analysis based on mt-rrs was carried out by constructing neighbor-joining tree topology to clarify the genetic variation of local D. steini. Based on external morphological characterizations, all ticks were successfully identified down to the species as adult D. steini. The molecular traits based on phylogenetic tree provide very strong support for the monophyletic clade of D. steini including high percentages of similarity (97-100%) with available sequences in GenBank. Furthermore, a low intraspecific variation (4%) among the species of D. steini was observed but it was genetically different from other Dermacentor species with high interspecific value (8-15%). These findings produced the first genotypic data of D. steini using 16S rDNA gene which confirmed the presence of this species in Malaysia. Moreover, this study supports the taxonomic status of local D. steini and adds to the knowledge of accurate identification of ticks.

Description of a new species of Dermacentor Koch, 1844 (Acari: Ixodidae) from Laos and Thailand.

Dermacentor laothaiensis n. sp. (Acari: Ixodidae) is described based on adults ex wild boar and vegetation from Laos and Thailand. Adults of D. laothaiensis n. sp. are similar to those of D. bellulus (Schulze, 1935) and D. steini (Schulze, 1933) but can be distinguished by the conscutum shape, colour pattern of the conscutum and scutum, the density of punctations on the pseudoscutum and scutum and the shape of female genital structures.

Microsatellite-based genetic diversity of Dermacentor reticulatus in Europe.

Dermacentor reticulatus, also known as ornate dog tick, is an important vector of the causative agents of various tick-borne diseases in humans, livestock and wild animals. The geographical range of D. reticulatus in Europe is fragmented and divided into two main zones: The Western European and the Eastern European zone. To investigate D. reticulatus population structure through its distribution range we used microsatellite markers and compared the genetic diversity of D. reticulatus in 26 selected sites in the western and eastern European distribution areas. A total of 254 unfed adult D. reticulatus ticks were collected from vegetation and genotyped at 5 microsatellite loci, and altogether 26 alleles were detected. The overall FST value of pairwise comparisons among 26 sampling sites was 0.128 and revealed a moderate genetic differentiation. Bayesian-clustering analysis showed that D. reticulatus forms two genetically distinct groups across Europe. Division of D. reticulatus distribution range into Eastern European and Western European populations with a possible recent overlap in Poland has been supported by molecular data obtained in this study.

Range-wide genetic analysis of Dermacentor variabilis and its Francisella-like endosymbionts demonstrates phylogeographic concordance between both taxa.

BACKGROUND: The American dog tick, Dermacentor variabilis, is an important vector of pathogens to humans, wildlife and domestic animals in North America. Although this tick species is widely distributed in the USA and Canada, knowledge of its range-wide phylogeographic patterns remains incomplete. METHODS: We carried out a phylogenetic analysis of D. variabilis using samples collected from 26 USA states and five Canadian provinces. Tick samples (n = 1053 in total) originated from two main sources: existing archives (2000-2011), and new collections made from 2012 to 2013. We sequenced a 691 bp fragment of the cox1 gene from a subset (n = 332) of geographically diverse D. variabilis. DNA extracted from individual ticks (n = 1053) was also screened for a Francisella-like endosymbiont, using a targeted 16S rRNA sequencing approach, and important pathogens (Rickettsia spp. and Coxiella burnetii), using species-specific quantitative PCR assays. RESULTS: Maximum parsimony analysis of cox1 sequences revealed two major groups within D. variabilis with distinct geographical distributions: one from the eastern USA/Canada (Group 1) and one from the west coast states of the USA (California and Washington; Group 2). However, genetic subdivisions within both of these two major groups were weak to moderate and not tightly correlated with geography. We found molecular signatures consistent with Francisella-like endosymbionts in 257 of the DNA extracts from the 1053 individual ticks, as well as Rickettsia spp. and Coxiella burnetii in a small number of ticks (n = 29 and 2, respectively). Phylogenetic patterns for Francisella-like endosymbionts, constructed using sequence data from the bacterial 16S rRNA locus, were similar to those for D. variabilis, with two major groups that had a nearly perfect one-to-one correlation with the two major groups within D. variabilis. CONCLUSIONS: Our findings reveal a distinct phylogenetic split between the two major D. variabilis populations. However, high levels of genetic mixture among widely separated geographical localities occur within each of these two major groups. Furthermore, our phylogenetic analyses provide evidence of long-term tick-symbiont co-evolution. This work has implications for understanding the dispersal and evolutionary ecology of D. variabilis and associated vector-borne diseases.

Morphometric Analysis of Adult Dermacentor parumapertus Neumann (Acari: Ixodidae) From Various Locations Within its Geographical Range.

Dermacentor parumapertus Neumann (Acari: Ixodidae), a tick primarily associated with rabbits which occurs over much of the western United States, has a fairly large north-to-south distribution, being found from central Idaho southward into northern Mexico. This mostly obscure tick species has recently been the focus of attention due to the discovery of a unique strain of Rickettsia parkeri associated with it which appears closely related to a Rickettsia sp. found in the Atlantic rainforest of Brazil. Historically, a morphological variety of this species was reported in the literature based on significant variation in ornamentation of the tick throughout its range. This study examines several key morphological characters to determine if there are indeed more than one distinct population of this species throughout its range.

The Genus Dermacentor (Acari: Ixodidae) in Laos: A Review and Update of Species Records.

Two species of the ixodid tick genus Dermacentor Koch, 1844 (Acari: Ixodidae) have previously been documented from Laos: D. auratus Supino, 1897 and D. steini (Schulze, 1933). Between 2012 and 2017, we recorded four additional Dermacentor species from this country: D. bellulus (Schulze, 1935); D. compactus Neumann, 1901; D. filippovae Apanaskevich & Apanaskevich, 2015; and D. tamokensisApanaskevich & Apanaskevich, 2016. In addition, seven specimens in the tick collection at the Institut Pasteur du Laos may represent new species and are currently under taxonomic investigation.

MOLECULAR SURVEILLANCE FOR BARTONELLA, BORRELIA, AND RICKETTSIA SPECIES IN TICKS FROM DESERT BIGHORN SHEEP ( OVIS CANADENSIS) AND MULE DEER ( ODOCOILEUS HEMIONUS) IN SOUTHERN CALIFORNIA, USA.

: Ticks (Acari: Ixodidae) were collected from 44 desert bighorn sheep ( Ovis canadensis) and 10 mule deer ( Odocoileus hemionus) in southern California, US during health inspections in 2015-16. Specimens were identified and screened by PCR analysis to determine the presence and prevalence of Bartonella, Borrelia, and Rickettsia species in ticks associated with these wild ruminants. None of the 60 Dermacentor hunteri and 15 Dermacentor albipictus ticks tested yielded positive PCR results. Additional tick specimens should be collected and tested to determine the prevalence of these confirmed or suspected tickborne pathogens within ruminant populations.

Novel Rickettsia raoultii strain isolated and propagated from Austrian Dermacentor reticulatus ticks

Continuous culture of tick cell lines has proven a valuable asset in isolating and propagating several different vector-borne pathogens, making it possible to study these microorganisms under laboratory conditions and develop serological tests to benefit public health. We describe a method for effective, cost- and labor-efficient isolation and propagation of Rickettsia raoultii using generally available laboratory equipment and Rhipicephalus microplus cells, further demonstrating the usefulness of continuous tick cell lines. R. raoultii is one of the causative agents of tick-borne lymphadenopathy (TIBOLA) and is, together with its vector Dermacentor reticulatus, emergingin novel regions of Europe, giving rise to an increased threat to general public health...

Complete mitochondrial genomes of Dermacentor silvarum and comparative analyses with another hard tick Dermacentor nitens.

Ticks are obligate blood-sucking ectoparasites of a wide range of vertebrates. They can transmit a range of pathogens that cause economic losses to livestock production as well as human disease. In the present study, the complete mitochondrial (mt) genome of Dermacentor silvarum was determined. The mt genome is 14,945 bp in length contains 37 genes, including 13 are protein-coding genes (cox1-3, nad1-6, nad4L, cytb, atp6 and atp8), two ribosomal RNA genes and 22 transfer RNA genes. The nucleotide composition of the D. silvarum mt genome was A + T biased at 78.78%; T was the most abundant nucleotide and G the least abundant. The mt genome of D. silvarum was 106 bp longer than that of Dermacentor nitens and the arrangements of two genomes were identical. For the 13 protein-coding genes, comparison between D. silvarum and D. nitens revealed sequence divergence at both the nucleotide (15.46-35.14%) and amino acid (6.05-48.98%) levels. Among them, cox1 was the most conserved gene, while atp8 was the least conserved. The lengths of the 13 protein-coding genes were the same or similar, except for cytb which was significantly longer in D. silvarum than in D. nitens. The mtDNA contained a variable repeat region consisting of a "similar to nad1" motif that was repeated three times, and the "Tick-box" motifs were also found. The overall difference between the nucleotide sequences of the two complete mt genomes was 21.4%. The mtDNA data presented in this study provide a rich resource for further studies on the phylogenetics, population genetics, and molecular epidemiology of ticks.

Ticks infesting domestic dogs in the UK: a large-scale surveillance programme.

BACKGROUND: Recent changes in the distribution of tick vectors and the incidence of tick-borne disease, driven variously by factors such as climate change, habitat modification, increasing host abundance and the increased movement of people and animals, highlight the importance of ongoing, active surveillance. This paper documents the results of a large-scale survey of tick abundance on dogs presented to veterinary practices in the UK, using a participatory approach that allows relatively cost- and time-effective extensive data collection. METHODS: Over a period of 16 weeks (April-July 2015), 1094 veterinary practices were recruited to monitor tick attachment to dogs and provided with a tick collection and submission protocol. Recruitment was encouraged through a national publicity and communication initiative. Participating practices were asked to select five dogs at random each week and undertake a thorough, standardized examination of each dog for ticks. The clinical history and any ticks were then sent to the investigators for identification. RESULTS: A total of 12,000 and 96 dogs were examined and 6555 tick samples from infested dogs were received. Ixodes ricinus (Linnaeus) was identified on 5265 dogs (89 %), Ixodes hexagonus Leach on 577 (9.8 %) and Ixodes canisuga Johnston on 46 (0.8 %). Ten dogs had Dermacentor reticulatus (Fabricius), one had Dermacentor variabilis (Say), three had Haemaphysalis punctata Canesteini & Fanzago and 13 had Rhipicephalus sanguineus Latreille. 640 ticks were too damaged for identification. All the R. sanguineus and the single D. variabilis were on dogs with a recent history of travel outside the UK. The overall prevalence of tick attachment was 30 % (range 28-32 %). The relatively high prevalence recorded is likely to have been inflated by the method of participant recruitment. CONCLUSION: The data presented provide a comprehensive spatial understanding of tick distribution and species abundance in the UK against which future changes can be compared. Relative prevalence maps show the highest rates in Scotland and south west England providing a valuable guide to tick-bite risk in the UK.