Publications by authors named "Neil B Chilton"

83 Publications

Traceback of the outbreak in British Columbian bighorn sheep ().

Int J Parasitol Parasites Wildl 2021 Apr 10;14:273-279. Epub 2021 Mar 10.

Large Animal Clinical Sciences, Western College of Veterinary Medicine, University of Saskatchewan, 52 Campus Dr., Saskatoon, Saskatchewan, S7N5B4, Canada.

are a non-burrowing, ectoparasitic, mange-causing mite that has been documented in American bighorn sheep populations throughout the 19th and 20th centuries; however, it was not seen on Canadian bighorn sheep until 2006. The aim of this study was to determine the potential source of the outbreak in Canadian bighorn sheep. Morphological and molecular analyses were used to compare mites recovered from outbreak-associated bighorn sheep, pet rabbits in Canada, and on historically infested bighorn sheep in the USA. The results revealed that acquired from the Canadian and outbreak-associated American bighorn sheep were morphologically more similar to those collected from rabbits than mites on historically infested bighorn sheep. Outer opisthosomal setae lengths measured an average of 81.7 μm (±7.7 μm) in outbreak associated bighorn mites, 88.9 μm (±12.0 μm) in rabbit mites and 151.2 μm (±16.6 μm) in historically infested bighorn mites. The opisthosomal lobe morphology of bighorn mites in the outbreak herds was also more similar to that of rabbit mites, previously described as , than historically infested bighorn mites, which match previous descriptions of . This finding was supported by DNA sequence data of the mitochondrial cytochrome B gene. This is the first report of of the rabbit ecotype on bighorn sheep. The morphological and molecular data therefore support the hypothesis that the source of outbreak in Canadian bighorn sheep represented a disease spillover event from rabbits rather than transmission from infested American bighorn sheep populations.
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http://dx.doi.org/10.1016/j.ijppaw.2021.02.017DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8056144PMC
April 2021

Distribution of Dermacentor andersoni (Acari: Ixodidae) in Grassland Regions of Alberta, Canada.

J Med Entomol 2021 07;58(4):1750-1761

Lethbridge Research and Development Centre, Agriculture and Agri-Food Canada, Lethbridge, AB, Canada.

The geographic distribution of the Rocky Mountain wood tick, Dermacentor andersoni Stiles, was determined in Alberta, Canada, by drag sampling at 86 and 89 sites during 2011 and 2012, respectively. Tick density and prevalence varied between years, averaging (range) 1.0 (0-26.2) and 5.9 (0-110) ticks/1,000 m2 in 2011 and 2012, respectively. Ticks were detected at 24.4% and 42.7% of the sites sampled in each respective year. Tick density and presence declined in a northerly direction to 51.6°N and in a westerly direction to ca. 113°W, except for a small area of high density at the edge of the Rocky Mountains in the southeastern portion of the province. Ticks were most abundant in the Dry Mixedgrass and Montane natural subregions and in areas with Brown Chernozemic, Regosol, and Solodized Solonetzic great soil groups. A logistic regression model indicated that tick presence was increased in the Dry Mixedgrass natural subregion and in regions with greater temperatures during the previous summer and normal winter precipitation but was reduced in areas with Dark Brown Chernozemic soils. The model will be useful for predicting tick presence and the associated risk of tick-borne diseases in the province.
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http://dx.doi.org/10.1093/jme/tjab019DOI Listing
July 2021

Molecular Differentiation of Four Species of Oropsylla (Siphonaptera: Ceratophyllidae) Using PCR-Based Single Strand Conformation Polymorphism Analyses and DNA Sequencing.

J Med Entomol 2021 01;58(1):241-245

Department of Biology, University of Saskatchewan, Saskatoon, Saskatchewan, Canada.

It is often difficult to distinguish morphologically between closely related species of fleas (Siphonaptera). Morphological identification of fleas often requires microscopic examination of internal structures in specimens cleared using caustic solutions. This process degrades DNA and/or inhibits DNA extraction from specimens, which limits molecular-based studies on individual fleas and their microbiomes. Our objective was to distinguish between Oropsylla rupestris (Jordan), Oropsylla tuberculata (Baker), Oropsylla bruneri (Baker), and Oropsylla labis (Jordan & Rothschild) (Ceratophyllidae) using PCR-based single strand conformation polymorphism (SSCP) analyses and DNA sequencing. A 446 bp region of the nuclear 28S ribosomal RNA (rRNA) gene was used as the genetic marker. The results obtained for 36 reference specimens (i.e., fleas that were morphologically identified to species) revealed no intraspecific variation in DNA sequence, whereas the DNA sequences of the four species of Oropsylla differed from one another at two to six nucleotide positions. Each flea species also had a unique SSCP banding pattern. SSCP analyses were then used to identify another 84 fleas that had not been identified morphologically. DNA sequencing data confirmed the species identity of fleas subjected to SSCP. This demonstrates that PCR-SSCP combined with DNA sequencing of the 28S rRNA gene is a very effective approach for the delineation of four closely related species of flea.
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http://dx.doi.org/10.1093/jme/tjaa161DOI Listing
January 2021

Reproductive output and larval survival of American dog ticks (Dermacentor variabilis) from a population at the northern distributional limit.

Exp Appl Acarol 2021 Feb 4;83(2):257-270. Epub 2021 Jan 4.

Department of Biology, University of Saskatchewan, 112 Science Place, Saskatoon, SK, S7N 5E2, Canada.

Female reproductive output and larval survival were determined for American dog ticks, Dermacentor variabilis (Say), from a recently established population near the northern distributional limit in Saskatchewan (Canada). Oviposition took 10-21 days at 25 °C and 95% relative humidity (RH). Temperature and relative humidity had a marked effect on egg development time and larval survival. Unfed larvae survived more than 100 days at 32 °C (with 95% RH) and 25 and 5 °C (with ≥ 85% RH). However, survival times declined markedly at lower relative humidities. In addition, 95% of the larvae placed in field enclosures survived for 140 days over winter during which they were exposed to sub-zero temperatures and 95-100% RH, while covered with snow. The median survival times (LT) of unfed larvae submerged underwater was 68 days. These results show that D. variabilis larvae in populations near the periphery of the northern distributional limit are adapted to cope with sub-zero temperatures in winter, and can survive in the temporary pools of water created by the spring snow melt.
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http://dx.doi.org/10.1007/s10493-020-00581-4DOI Listing
February 2021

Molecular identification of Stylops advarians (Strepsiptera: Stylopidae) in western Canada.

Parasitol Res 2020 Dec 4;119(12):4255-4258. Epub 2020 Nov 4.

Department of Biology, University of Saskatchewan, 112 Science Place, Saskatoon, Saskatchewan, S7N 5E2, Canada.

Strepsiptera are an enigmatic order of insects with extreme sexual dimorphism which makes it difficult to "match-up" free-living adult males with parasitic conspecific females of the Stylopidia, and free-living females of the Mengenillidae using morphological characters. Species identification is further complicated for the Stylopidia because adult females are endoparasitic and neotenic. Therefore, we used DNA sequencing of the mitochondrial cytochrome c oxidase subunit 1 gene (cox1) to confirm the species identity of adult strepsipterans that were morphologically identified as Stylops advarians. These specimens, collected from Saskatoon (Saskatchewan, Canada), included one adult male, and eight females, the latter of which had been collected from solitary bees (Andrena milwaukeensis). Also included in the analyses were three pools of first-instar larvae that had emerged from three of the females. The results of the molecular analyses revealed that all specimens had an identical cox1 sequence, and belonged to a clade, with total statistical support (bootstrap value of 100%), that contained specimens of S. advarians from New York and Maine (USA). Hence, the results were consistent with the morphological identification of S. advarians. This study demonstrates the usefulness of a molecular approach for the identification of endoparasitic adult female and larval strepsipterans, life cycle stages that lack significant morphological characters for species identification.
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http://dx.doi.org/10.1007/s00436-020-06946-3DOI Listing
December 2020

Supercooling Points of Adult Dermacentor variabilis (Acari: Ixodidae) From a Population Near the Northern Distribution Limit.

J Med Entomol 2021 03;58(2):961-964

Department of Biology, University of Saskatchewan, Saskatoon, Saskatchewan, Canada.

The northern distributional limit of Dermacentor variabilis Say, the American dog tick, is expanding in Saskatchewan and Manitoba (western Canada). The ability of D. variabilis to continue to expand its range northwards will depend upon the ability of individuals within populations at the species distributional edge to withstand very low temperatures during winter. One component of cold hardiness is the supercooling point (SCP), the temperature below 0°C at which an individual freezes. In this study, the SCP was determined for 94 questing D. variabilis adults (44 females and 50 males) from an established population near Blackstrap Provincial Park in Saskatchewan. SCP values ranged from -18.2 to -6.7°C, with a median of -13.3°C. This suggests that host-seeking D. variabilis adults differ in their ability to survive exposure to subzero temperatures, for at least a short period of time, without freezing. The distribution of SCPs was bimodal, but there was no significant difference in SCP values between female and male ticks, and no relationship between SCP and tick body weight. It remains to be determined what factors contribute to the variation in SCP values among questing D. variabilis adults.
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http://dx.doi.org/10.1093/jme/tjaa223DOI Listing
March 2021

Molecular detection and characterization of Hepatozoon canis in stray dogs from Cuba.

Parasitol Int 2021 Feb 25;80:102200. Epub 2020 Sep 25.

Centro Nacional de Sanidad Agropecuaria (CENSA), Carretera de Tapaste y Autopista Nacional, Apartado postal 10, 32700 San José de las Lajas, Mayabeque, Cuba. Electronic address:

Canine hepatozoonosis caused by Hepatozoon canis is a worldwide distributed tick-borne disease of domestic and wild canids that is transmitted by ingestion of Rhipicephalus sanguineus sensu lato (s.l.) ticks. The present study was aimed to determine the prevalence of Hepatozoon infections in 80 stray dogs from Havana Province in Cuba, and to confirm the species identity and phylogenetic relationships of the causative agent. Samples were screened by microscopical examination of thin blood smears for the presence of Hepatozoon spp. gamonts and by genus-specific SYBR green-based real-time PCR assay targeting the 18S rRNA gene. Direct microscopy examination revealed Hepatozoon gamonts in the peripheral blood of 8 dogs (10.0%; 95% CI: 4.80-18.0%), while 38 animals (47.5%; 95% CI: 36.8-58.4%) were PCR-positive, including all microscopically positive dogs. Hence, the agreement between the two detection methods was 'poor' (κ = 0.20). Hematological parameters did not differ significantly between PCR-positive and PCR-negative dogs (p > 0.05). The DNA sequences of the 18S rRNA gene of the Hepatozoon spp. from Cuban dogs showed a nucleotide identity >99% with those of 18S rRNA sequences of Hepatozoon canis isolates from Czech Republic, Brazil and Spain. Phylogenetic analysis revealed that obtained sequences clustered within the Hepatozoon canis clade, different from the Hepatozoon felis or Hepatozoon americanum clades. The present study represents the first molecular characterization of Hepatozoon canis in stray dogs within Cuba.
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http://dx.doi.org/10.1016/j.parint.2020.102200DOI Listing
February 2021

Hopping species and borders: detection of Bartonella spp. in avian nest fleas and arctic foxes from Nunavut, Canada.

Parasit Vectors 2020 Sep 14;13(1):469. Epub 2020 Sep 14.

Department of Veterinary Microbiology, Western College of Veterinary Medicine, University of Saskatchewan, 52 Campus Drive, Saskatoon, SK, S7N 5B4, Canada.

Background: In a warmer and more globally connected Arctic, vector-borne pathogens of zoonotic importance may be increasing in prevalence in native wildlife. Recently, Bartonella henselae, the causative agent of cat scratch fever, was detected in blood collected from arctic foxes (Vulpes lagopus) that were captured and released in the large goose colony at Karrak Lake, Nunavut, Canada. This bacterium is generally associated with cats and cat fleas, which are absent from Arctic ecosystems. Arctic foxes in this region feed extensively on migratory geese, their eggs, and their goslings. Thus, we hypothesized that a nest flea, Ceratophyllus vagabundus vagabundus (Boheman, 1865), may serve as a vector for transmission of Bartonella spp.

Methods: We determined the prevalence of Bartonella spp. in (i) nest fleas collected from 5 arctic fox dens and (ii) 37 surrounding goose nests, (iii) fleas collected from 20 geese harvested during arrival at the nesting grounds and (iv) blood clots from 57 adult live-captured arctic foxes. A subsample of fleas were identified morphologically as C. v. vagabundus. Remaining fleas were pooled for each nest, den, or host. DNA was extracted from flea pools and blood clots and analyzed with conventional and real-time polymerase chain reactions targeting the 16S-23S rRNA intergenic transcribed spacer region.

Results: Bartonella henselae was identified in 43% of pooled flea samples from nests and 40% of pooled flea samples from fox dens. Bartonella vinsonii berkhoffii was identified in 30% of pooled flea samples collected from 20 geese. Both B. vinsonii berkhoffii (n = 2) and B. rochalimae (n = 1) were identified in the blood of foxes.

Conclusions: We confirm that B. henselae, B. vinsonii berkhoffii and B. rochalimae circulate in the Karrak Lake ecosystem and that nest fleas contain B. vinsonii and B. henselae DNA, suggesting that this flea may serve as a potential vector for transmission among Arctic wildlife.
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http://dx.doi.org/10.1186/s13071-020-04344-3DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7490881PMC
September 2020

American Dog Ticks (Dermacentor variabilis) as Biological Indicators of an Association between the Enteric Bacterium Moellerella wisconsensis and Striped Skunks (Mephitis mephitis) in Southwestern Manitoba, Canada.

J Wildl Dis 2020 10;56(4):918-921

Department of Biology, University of Saskatchewan, 112 Science Place, Saskatoon, Saskatchewan, Canada S7N 5E2.

Total genomic (g)DNA from 100 American dog ticks (Dermacentor variabilis) collected from humans, dogs, raccoons, and skunks near Minnedosa (Manitoba, Canada) in 2005 was tested for the presence of Moellerella wisconsensis (Gammaproteobacteria: Enterobacteriales) using PCR. Although two gDNA samples derived from ticks attached to two striped skunks (Mephitis mephitis) contained M. wisconsensis DNA, it is unlikely that D. variabilis is a vector of this bacterium. Genomic DNA prepared from the washes of the external surfaces of these two ticks (i.e., before DNA extraction from the whole tick) and another two ticks attached to same skunks were also PCR positive for M. wisconsensis. This suggests that ticks acquired the bacterium by physical contact with contaminated or infected skunks. However, it does not exclude the possibility that the ticks may have also imbibed the bacterium from their host blood and lymph. Nonetheless, the results of this molecular study suggest that the four adult D. variabilis represent biological indicators of the presence of M. wisconsensis in association with their vertebrate hosts (i.e., striped skunks). Additional work is needed to determine if M. wisconsensis is present in the blood and lymph of striped skunks in southwestern Manitoba and if there are potential health risks for persons coming into contact with infected animals.
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http://dx.doi.org/10.7589/2019-09-224DOI Listing
October 2020

Identification of bacteria in the Rocky Mountain wood tick, Dermacentor andersoni, using single-strand conformation polymorphism (SSCP) and DNA sequencing.

Exp Appl Acarol 2020 Feb 17;80(2):247-256. Epub 2020 Jan 17.

Department of Biology, University of Saskatchewan, 112 Science Place, Saskatoon, SK, S7N 5E2, Canada.

PCR-based single-strand conformation polymorphism (SSCP) analyses combined with DNA sequencing of the prokaryotic 16S ribosomal (r) RNA gene encompassing the hypervariable V4 region was used to determine the bacterial composition of Rocky Mountain wood ticks (Dermacentor andersoni) attached to Richardson's ground squirrels (Urocitellus richardsonii) and questing on vegetation in southern Saskatchewan, Canada. The bacteria present in questing adult ticks from Saskatchewan Landing Provincial Park included Rickettsia peacockii, a Francisella-like endosymbiont (FLE) and an Arsenophonus-like endosymbiont. Bacteria in the adult and nymphal ticks attached to U. richardsonii collected from Beechy included R. peacockii, a FLE, and several other genera (e.g., Ralstonia, Sphingobium, Comamonas and Pseudomonas). The bacteria detected in D. andersoni in the present study are consistent with the findings of other studies that have characterized the microbiome of this tick species in the USA using next generation sequencing. This result demonstrates that the SSCP-based approach used in this study is cost- and time-effective for examining bacterial composition in ticks.
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http://dx.doi.org/10.1007/s10493-019-00459-0DOI Listing
February 2020

Passive and Active Surveillance for Ixodes scapularis (Acari: Ixodidae) in Saskatchewan, Canada.

J Med Entomol 2020 01;57(1):156-163

Lethbridge Research and Development Centre, Agriculture and Agri-Food Canada, Lethbridge, AB, Canada.

Passive and active surveillance for the blacklegged tick, Ixodes scapularis Say, in the Canadian province of Saskatchewan was conducted over a 9-yr period (2009-2017). More than 26,000 ixodid ticks, representing 10 species, were submitted through passive surveillance. Most (97%) of these were the American dog tick, Dermacentor variabilis (Say). Of the 65 I. scapularis adults submitted, 75% were collected from dogs. Infection rates of Borrelia burgdorferi, Anaplasma phagocytophilum, and Babesia microti in I. scapularis were 12%, 8%, and 0%, respectively. Although the I. scapularis submitted by passive surveillance were collected from five of seven ecoregions in central and southern Saskatchewan, they were most frequent in the Moist Mixed Grassland and Aspen Parklands. In contrast, no I. scapularis were collected from the extensive field sampling conducted at multiple sites in different ecoregions across the province. Hence, there is no evidence of I. scapularis having established a breeding population in Saskatchewan. Nonetheless, continued surveillance for blacklegged ticks is warranted given their important role as a vector of medically and veterinary important pathogens, and because they have recently become established across much of the southern portions of the neighboring province of Manitoba.
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http://dx.doi.org/10.1093/jme/tjz155DOI Listing
January 2020

Genetic variation within the genus (Nematoda: Strongyloidea) from Australian macropodid and vombatid marsupials.

Parasitology 2019 11 28;146(13):1673-1682. Epub 2019 Aug 28.

Department of Veterinary Biosciences, Melbourne Veterinary School, University of Melbourne, Werribee, Victoria, Australia.

The genetic variation and taxonomic status of the four morphologically-defined species of Macropostrongyloides in Australian macropodid and vombatid marsupials were examined using sequence data of the ITS+ region (=first and second internal transcribed spacers, and the 5.8S rRNA gene) of the nuclear ribosomal DNA. The results of the phylogenetic analyses revealed that Ma. baylisi was a species complex consisting of four genetically distinct groups, some of which are host-specific. In addition, Ma. lasiorhini in the common wombat (Vombatus ursinus) did not form a monophyletic clade with Ma. lasiorhini from the southern hairy-nosed wombat (Lasiorhinus latifrons), suggesting the possibility of cryptic (genetically distinct but morphologically similar) species. There was also some genetic divergence between Ma. dissimilis in swamp wallabies (Wallabia bicolor) from different geographical regions. In contrast, there was no genetic divergence among specimens of Ma. yamagutii across its broad geographical range or between host species (i.e. Macropus fuliginosus and M. giganteus). Macropostrongyloides dissimilis represented the sister taxon to Ma. baylisi, Ma. yamagutii and Ma. lasiorhini. Further morphological and molecular studies are required to assess the species complex of Ma. baylisi.
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http://dx.doi.org/10.1017/S0031182019001008DOI Listing
November 2019

Prevalence of Anaplasma bovis in Canadian populations of the Rocky Mountain wood tick, Dermacentor andersoni.

Ticks Tick Borne Dis 2018 09 29;9(6):1528-1531. Epub 2018 Jul 29.

Lethbridge Research and Development Centre, Agriculture and Agri-Food Canada, Lethbridge, Alberta, T1J 4B1, Canada.

PCR and DNA sequencing were used to determine the prevalence of Anaplasma bovis in Rocky Mountain wood ticks (Dermacentor andersoni) collected in Alberta and Saskatchewan, Canada. These analyses revealed that A. bovis DNA was present in 35 (2.1%) of 1679 ticks collected at 12 of the 24 localities. The discovery of A. bovis in host-seeking female and male D. andersoni from multiple locations in southern Canada may have important implications for diagnosis of anaplasmosis in Canada.
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http://dx.doi.org/10.1016/j.ttbdis.2018.07.003DOI Listing
September 2018

Three genetically distinct clades of Anaplasma phagocytophilum in Ixodes scapularis.

Ticks Tick Borne Dis 2018 09 5;9(6):1518-1527. Epub 2018 Jul 5.

Department of Biology, University of Saskatchewan, Canada. Electronic address:

Human granulocytic anaplasmosis (HGA) is an emerging disease in Canada because of range expansion by the arthropod vector, Ixodes scapularis. These ticks carry the Ap-ha variant of Anaplasma phagocytophilum (Ap-ha), which has been implicated in causing HGA, and the Ap-variant 1, which is not associated with human infection. We report the detection of 13 genotypes of the ankyrin (ankA) gene among 76 infected blacklegged ticks. Haplotype network and phylogenetic analyses revealed that the ankA genotypes corresponding to the Ap-ha variant did not form a monophyletic assemblage. They formed two distinct clades (Clades I and III), one of which was genetically more similar in nucleotide and amino acid sequences to genotypes of Ap-variant 1 that comprised Clade II. Additional work is needed to explore the evolutionary history of A. phagocytophilum in North America, and to determine if there are differences in pathogenicity or clinical symptoms associated with the two divergent groups of the Ap-ha variant given the significant differences in ankA amino acid sequence.
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http://dx.doi.org/10.1016/j.ttbdis.2018.07.002DOI Listing
September 2018

Pharyngostrongylus thylogale n. sp. (Nematoda: Strongylida) from the stomachs of macropodid marsupials defined by morphological and molecular criteria.

Syst Parasitol 2016 10 14;93(8):749-60. Epub 2016 Sep 14.

Faculty of Veterinary and Agricultural Sciences, The University of Melbourne, Parkville, VIC, Australia.

Pharyngostrongylus thylogale n. sp. (Nematoda: Strongylida) is described from the stomach of the red-legged pademelon, Thylogale stigmatica (Gould) (Marsupialia: Macropodidae) from north-eastern Queensland and Papua New Guinea, having formerly been confused with P. iota Johnston & Mawson, 1939. Pharyngostrongylus thylogale n. sp. differs from all congeners in having 12 labial crown elements rather than eight or 16. Pharyngostrongylus iota was found in T. stigmatica, but only in southern Queensland and northern New South Wales, in the subspecies T. s. wilcoxi, compared with P. thylogale n. sp. which was found in T. s. stigmatica in northern Queensland and T. s. oriomo in Papua New Guinea. Differences in the sequences of the first and second internal transcribed spacers (ITS-1 and ITS-2) of the nuclear ribosomal DNA of P. thylogale n. sp. and ten congeners support the erection of the new species, and the validity of the morphospecies examined. However, results of the phylogenetic analyses of the molecular data also provide evidence for the existence of cryptic species within P. kappa Mawson, 1965. No obvious co-evolutionary relationships were observed between parasite species and their macropodid marsupial hosts.
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http://dx.doi.org/10.1007/s11230-016-9661-9DOI Listing
October 2016

Detection of cryptic species of Rugopharynx (Nematoda: Strongylida) from the stomachs of Australian macropodid marsupials.

Int J Parasitol Parasites Wildl 2016 Aug 19;5(2):124-33. Epub 2016 Apr 19.

Faculty of Veterinary and Agricultural Sciences, The University of Melbourne, Parkville, VIC 3010, Australia.

Sequences of the internal transcribed spacers of nuclear ribosomal DNA (ITS-1 and ITS-2) were determined for species of the genus Rugopharynx and Rugonema labiatum, nematodes from the stomachs of macropodid marsupials. Phylogenetic analyses of the aligned sequence data were conducted. The relationships provided molecular support for all species currently recognised, some of which are based on minor morphological differences and on multilocus enzyme electrophoretic data, but also indicated that additional, cryptic species exist within the genus. In addition, the genus Rugonema is placed as a synonym of Rugopharynx, its sole species becoming Rugopharynx labiatum n. comb. The molecular data provided some insights into the evolution of complex buccal capsule morphologies within the genus, but there was no evidence of co-evolution between the macropodid hosts and their parasites.
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http://dx.doi.org/10.1016/j.ijppaw.2016.04.003DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4900440PMC
August 2016

Phylogenetic relationships of species of the oesophageal parasitic nematode genera Cyclostrongylus and Spirostrongylus (Strongyloidea: Chabertiidae: Cloacininae) with their wallaby hosts (Marsupialia: Macropodidae).

Mol Cell Probes 2016 Apr 21;30(2):93-9. Epub 2016 Jan 21.

Faculty of Veterinary and Agricultural Science, University of Melbourne, Parkville, Victoria, Australia.

A phylogeny for seven species of Cyclostrongylus and the monotypic genus Spirostrongylus (Nematoda: Chabertiidae), all highly host specific parasites of the oesophagi of wallabies (Marsupialia: Macropodidae), was constructed using sequence data for the first and second internal transcribed spacers (ITS-1 and ITS-2) of the nuclear ribosomal DNA. There was no evidence for co-speciation, or for the sympatric or synxenic speciation of Cyclostrongylus alatus and Cyclostrongylus perplexus, both of which are parasites of Macropus rufogriseus. Rather, host switching, correlating with geographical distributions, appeared to provide some explanation of the pattern of speciation observed.
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http://dx.doi.org/10.1016/j.mcp.2016.01.004DOI Listing
April 2016

Exploring molecular variation in Schistosoma japonicum in China.

Sci Rep 2015 Dec 1;5:17345. Epub 2015 Dec 1.

The University of Melbourne, Pathogen Genomics and Genetics Program, Parkville, Victoria 3010, Australia.

Schistosomiasis is a neglected tropical disease that affects more than 200 million people worldwide. The main disease-causing agents, Schistosoma japonicum, S. mansoni and S. haematobium, are blood flukes that have complex life cycles involving a snail intermediate host. In Asia, S. japonicum causes hepatointestinal disease (schistosomiasis japonica) and is challenging to control due to a broad distribution of its snail hosts and range of animal reservoir hosts. In China, extensive efforts have been underway to control this parasite, but genetic variability in S. japonicum populations could represent an obstacle to eliminating schistosomiasis japonica. Although a draft genome sequence is available for S. japonicum, there has been no previous study of molecular variation in this parasite on a genome-wide scale. In this study, we conducted the first deep genomic exploration of seven S. japonicum populations from mainland China, constructed phylogenies using mitochondrial and nuclear genomic data sets, and established considerable variation between some of the populations in genes inferred to be linked to key cellular processes and/or pathogen-host interactions. Based on the findings from this study, we propose that verifying intraspecific conservation in vaccine or drug target candidates is an important first step toward developing effective vaccines and chemotherapies against schistosomiasis.
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http://dx.doi.org/10.1038/srep17345DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4664899PMC
December 2015

The phylogenetic relationships of endemic Australasian trichostrongylin families (Nematoda: Strongylida) parasitic in marsupials and monotremes.

Parasitol Res 2015 Oct 10;114(10):3665-73. Epub 2015 Jul 10.

Department of Biology, University of Saskatchewan, Saskatoon, Saskatchewan, Canada,

The phylogenetic relationships of the endemic (or largely endemic) Australasian trichostrongylin nematode families Herpetostrongylidae, Mackerrastrongylidae and Nicollinidae as well as endemic trichostrongylin nematodes currently placed in the families Trichostrongylidae and Molineidae were examined using the complete large subunit (28S) ribosomal RNA gene. The Herpetostrongylinae proved to be monophyletic. However, representatives of the Nicollinidae nested with the Herpetostrongylinae. The Mackerrastrongylidae was also a monophyletic group and included Peramelistrongylus, currently classified within the Trichostrongylidae. The Globocephaloidinae, currently considered to be a subfamily of the Herpetostrongylidae, was excluded from the family in the current analysis. Ollulanus and Libyostrongylus, included for the first time in a molecular phylogenetic analysis, were placed within the Trichostrongylidae. This study provided strong support for the Herpetostrongylidae (including within it the Nicollinidae, but excluding the Globocephaloidinae) and the Mackerrastrongylidae as monophyletic assemblages. Additional studies are required to resolve the relationships of the remaining endemic Australasian trichostrongylin genera.
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http://dx.doi.org/10.1007/s00436-015-4594-9DOI Listing
October 2015

Comparison between available serologic tests for detecting antibodies against Anaplasma phagocytophilum and Borrelia burgdorferi in horses in Canada.

J Vet Diagn Invest 2015 Jul 11;27(4):540-6. Epub 2015 Jun 11.

Departments of Large Animal Clinical Sciences (Schvartz, Epp, Lohmann), University of Saskatchewan, Saskatoon, Saskatchewan, CanadaVeterinary Pathology (Burgess), University of Saskatchewan, Saskatoon, Saskatchewan, CanadaWestern College of Veterinary Medicine, and the Department of Biology (Chilton), University of Saskatchewan, Saskatoon, Saskatchewan, Canada.

To investigate the agreement between available serologic tests for the detection of antibodies against Anaplasma phagocytophilum and Borrelia burgdorferi, 50 serum samples from horses of unknown clinical status and at low risk for infection were tested. In addition to a point-of-care enzyme-linked immunosorbent assay (pocELISA), the evaluated tests included 2 indirect fluorescent antibody tests (IFATs) for antibodies against A. phagocytophilum and an IFAT, an ELISA confirmed with Western blot, and the Lyme multiplex assay for antibodies against B. burgdorferi. For each pair-wise comparison between serologic tests, the difference in the proportion of seropositive results as well as kappa and the prevalence-adjusted, bias-adjusted kappa were calculated. The proportion of seropositive results differed significantly in each pairwise comparison of tests for detection of antibodies against A. phagocytophilum, and between the pocELISA and IFAT as well as between the pocELISA and Lyme multiplex assay for detection of antibodies against B. burgdorferi. Agreement based on kappa varied from poor to fair while agreement was improved when evaluating prevalence-adjusted, bias-adjusted kappa. Lack of agreement may be explained by differences in methodology between the evaluated tests, cross-reactivity or false-positive and false-negative tests. In addition to the limitations of serologic test interpretation in the absence of clinical disease, this data suggest that screening of horses for exposure to tick-borne diseases in nonendemic areas may not be warranted.
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http://dx.doi.org/10.1177/1040638715587548DOI Listing
July 2015

Seroprevalence of equine granulocytic anaplasmosis and lyme borreliosis in Canada as determined by a point-of-care enzyme-linked immunosorbent assay (ELISA).

Can Vet J 2015 Jun;56(6):575-80

Department of Large Animal Clinical Sciences (Schvartz, Epp, Lohmann), Department of Veterinary Pathology (Burgess), Western College of Veterinary Medicine, and Department of Biology (Chilton), University of Saskatchewan, 52 Campus Drive, Saskatoon, Saskatchewan S7N 5B4; Department of Population Medicine, Ontario Veterinary College, University of Guelph, 50 Stone Road, Guelph, Ontario N1G 2W1 (Pearl).

Equine granulocytic anaplasmosis (EGA) and Lyme borreliosis (LB) are an emerging concern in Canada. We estimated the seroprevalence of EGA and equine LB by testing 376 convenience serum samples from 3 provinces using a point-of-care SNAP(®) 4Dx(®) ELISA (IDEXX Laboratories, Westbrook, Maine, USA), and investigated the agreement between the point-of-care ELISA and laboratory-based serologic tests. The estimated seroprevalence for EGA was 0.53% overall (0.49% in Saskatchewan, 0.71% in Manitoba), while the estimated seroprevalence for LB was 1.6% overall (0.49% in Saskatchewan, 2.86% in Manitoba). There was limited agreement between the point-of-care ELISA and an indirect fluorescent antibody test for EGA (kappa 0.1, PABAK 0.47) and an ELISA/Western blot combination for LB (kappa 0.23, PABAK 0.71). While the SNAP(®) 4Dx(®) ELISA yielded expected seroprevalence estimates, further evaluation of serologic tests for the purposes of disease exposure recognition may be needed.
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http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4431153PMC
June 2015

Passive surveillance for ticks on horses in Saskatchewan.

Can Vet J 2015 May;56(5):486-9

Department of Large Animal Clinical Sciences (Schvartz, Epp, Lohmann), Department of Veterinary Pathology (Burgess), Western College of Veterinary Medicine, University of Saskatchewan, 52 Campus Drive, Saskatoon, Saskatchewan S7N 5B4; Department of Biology, University of Saskatchewan, 112 Science Place, Saskatoon, Saskatchewan S7N 5E2 (Chilton, Armstrong).

Passive surveillance of ticks on horses in Saskatchewan revealed that the horses were parasitized by 3 species, Dermacentor albipictus, D. andersoni, and D. variabilis. The nymphs and adults of D. albipictus occurred on horses earlier in the year than did adults of the 2 other species.
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http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4399735PMC
May 2015

Sequence variability in the mitochondrial 12S rRNA and tRNA Val genes of Ixodes scapularis (Acari: Ixodidae) individuals shown previously to be genetically invariant.

Mol Cell Probes 2015 Jun 9;29(3):177-81. Epub 2015 Apr 9.

Department of Biology, University of Saskatchewan, Saskatoon, SK S7N 5E2, Canada. Electronic address:

The DNA sequences of the mitochondrial (mt) 12S rRNA and tRNA(Val) genes were characterized for 82 blacklegged ticks (Ixodes scapularis) that were genetically identical for Domains IV and V of the mt 16S rRNA gene. Thirty-one haplotypes, differed in sequence by 1-9 bp, were detected among the 82 ticks. Most nucleotide alterations in DNA sequence did not affect the stability of the secondary structures of the RNAs. The magnitude of the DNA sequence variation in the mt 12S rRNA and tRNA(Val) genes among blacklegged ticks suggests that this region of the mitochondrial genome has potential as a genetic marker for examining the population genetics and phylogeography of I. scapularis.
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http://dx.doi.org/10.1016/j.mcp.2015.03.010DOI Listing
June 2015

Sequence and secondary structure of the mitochondrial 16S ribosomal RNA gene of Ixodes scapularis.

Mol Cell Probes 2015 Feb 15;29(1):35-8. Epub 2014 Nov 15.

Department of Biology, University of Saskatchewan, 112 Science Place, Saskatoon, Saskatchewan S7N 5EZ, Canada. Electronic address:

The complete DNA sequences and secondary structure of the mitochondrial (mt) 16S ribosomal (r) RNA gene were determined for six Ixodes scapularis adults. There were 44 variable nucleotide positions in the 1252 bp sequence alignment. Most (95%) nucleotide alterations did not affect the integrity of the secondary structure of the gene because they either occurred at unpaired positions or represented compensatory changes that maintained the base pairing in helices. A large proportion (75%) of the intraspecific variation in DNA sequence occurred within Domains I, II and VI of the 16S gene. Therefore, several regions within this gene may be highly informative for studies of the population genetics and phylogeography of I. scapularis, a major vector of pathogens of humans and domestic animals in North America.
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http://dx.doi.org/10.1016/j.mcp.2014.11.001DOI Listing
February 2015

Genetic variation in the mitochondrial 16S ribosomal RNA gene of Ixodes scapularis (Acari: Ixodidae).

Parasit Vectors 2014 Nov 28;7:530. Epub 2014 Nov 28.

Department of Biology, University of Saskatchewan, Saskatoon, SK, S7N 5E2, Canada.

Background: Ixodes scapularis is a vector of several human pathogens in the United States, and there is geographical variation in the relative number of persons infected with these pathogens. Geographically isolated populations of I. scapularis have established or are in the process of establishing in southern Canada. Knowledge of the genetic variation within and among these populations may provide insight into their geographical origins in the United States and the potential risk of exposure of Canadians to the different pathogens carried by I. scapularis.

Methods: Part of the mitochondrial (mt) 16S ribosomal (r) RNA gene was amplified by PCR from 582 ticks collected from southern Canada, and Minnesota and Rhode Island in the United States. Sequence variation was examined in relation to the predicted secondary structure of the gene. Genetic diversity among populations was also determined.

Results: DNA sequence analyses revealed 52 haplotypes. Most mutational alterations in DNA sequence occurred at unpaired sites or represented partial compensatory base pair changes that maintained the stability of the secondary structure. Significant genetic variation was detected within and among populations in different geographical regions. A greater proportion of the haplotypes of I. scapularis from the Canadian Prairie Provinces were found in the Midwest of the United States than in other regions, whereas more of the haplotypes of I. scapularis from the Canadian Central and Atlantic Provinces occurred in the Northeast of the United States. Nonetheless, 58% of I. scapularis were of a haplotype that occurs in the Midwest and Northeast of the United States; thus, their geographical origins could not be determined.

Conclusions: There is considerable genetic variation in the mt 16S rRNA gene of I. scapularis. There is some evidence to support the hypothesis that some lineages of I. scapularis in the Atlantic and Central Provinces of Canada may be derived from colonizing individuals originating in the Northeast of the United States, whereas those in the Prairie Provinces may be derived from individuals originating in the Midwest of the United States. However, additional genetic markers are needed to test hypotheses concerning the geographical origins of I. scapularis in Canada.
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http://dx.doi.org/10.1186/s13071-014-0530-6DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4258262PMC
November 2014

Two Anaplasma phagocytophilum strains in Ixodes scapularis ticks, Canada.

Emerg Infect Dis 2014 Dec;20(12):2064-7

We developed PCR-based assays to distinguish a human pathogenic strain of Anaplasma phagocytophilum, Ap-ha, from Ap-variant 1, a strain not associated with human infection. The assays were validated on A. phagocytophilum-infected black-legged ticks (Ixodes scapularis) collected in Canada. The relative prevalence of these 2 strains in I. scapularis ticks differed among geographic regions.
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http://dx.doi.org/10.3201/eid2012.140172DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4257797PMC
December 2014

Genetic variation within and among species of Cloacina (Strongyloidea: Cloacinine) from the swamp wallaby, Wallabia bicolor (Marsupialia: Macropodidae).

Infect Genet Evol 2014 Dec 2;28:261-9. Epub 2014 Oct 2.

Faculty of Veterinary and Agricultural Sciences, The University of Melbourne, Werribee, Victoria, Australia. Electronic address:

This study examined genetic variation within and among species of Cloacina found in the swamp wallaby (Wallabia bicolor) collected at different localities along the eastern coast of Australia, and evaluated geographical distance as a potential driver for genetic variation. The first and second internal transcribed spacers (ITS-1 and ITS-2, respectively) of the nuclear ribosomal DNA were used to characterize individuals of 11 morphospecies of Cloacina that parasitize W. bicolor. The results of the molecular analyses revealed multiple genotypes for the nine morphospecies of Cloacina (i.e. Cloacina annulata, Cloacina edwardsi, Cloacina eos, Cloacina gallardi, Cloacina mawsonae, Cloacina papillata, Cloacina papillatissima, Cloacina pollux, and Cloacina wallabiae) for which multiple individuals were available for analysis. However, phylogenetic analyses of the sequence data revealed that for each morphospecies, there was no subdivision of individuals into distinct clades based on geographical region from which they were collected. Additional studies are needed to determine the drivers of genetic variation in cloacinid nematodes, and hence increase our understanding of the diversity of parasitic nematodes in macropodid marsupials.
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http://dx.doi.org/10.1016/j.meegid.2014.09.031DOI Listing
December 2014

Ticks (Acari: Ixodidae) on small mammals in Kootenay National Park, British Columbia, Canada.

J Med Entomol 2013 Nov;50(6):1208-14

Two hundred and ninety-one ticks (i.e., 185 larvae, 72 nymphs, and 34 adults) were removed from 153 small mammals comprising six species collected in Verdant Forest, Numa Forest, and Marble Canyon within Kootenay National Park, British Columbia, Canada. Morphological examination and molecular analyses (i.e., polymerase chain reaction-single-strand conformation polymorphism [PCR-SSCP] and DNA sequencing of the mitochondrial 16S rRNA gene) of the ticks revealed that most individuals were Ixodes angustus Neumann. All life cycle stages of I. angustus were found primarily on southern red-backed voles, Clethrionomys gapperi (Vigors). Two Dermacentor andersoni Stiles females were also found on these small mammals. The results of the molecular analyses also revealed that there were three 16S haplotypes of I. angustus and two 16S haplotypes of D. andersoni. A comparison of available sequence data suggests genetic divergence between I. angustus near the western and eastern limits of the species distributional range in North America. Additional studies are needed to determine whether there are genetic differences between I. angustus from North America, Japan, and Russia, and whether there is geographical variation in the ability of ticks to transmit pathogens to their mammalian hosts.
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http://dx.doi.org/10.1603/me13067DOI Listing
November 2013

Comparison of the DNA sequences and secondary structure of the mitochondrial 16S rRNA gene of Ixodes kingi, Ixodes sculptus and Ixodes angustus.

Mol Cell Probes 2014 Aug 18;28(4):155-62. Epub 2014 Feb 18.

Department of Biology, University of Saskatchewan, 112 Science Place, Saskatoon, SK, Canada S7N 5E2. Electronic address:

The DNA sequences and predicted secondary structure of domains IV and V of the mitochondrial (mt) 16S rRNA gene were compared for three species of Ixodes: Ixodes kingi, Ixodes sculptus and Ixodes angustus. Each species had a unique set of DNA sequences for the 16S gene. Many of the differences in DNA sequence within and among species occurred in a "hypervariable" region of domain V, and either represented partial or full compensatory base pair changes that maintained the helices within the secondary structure, or nucleotide alterations at unpaired positions that had no effect on the secondary structure. The results of the phylogenetic analyses revealed that I. kingi, I. sculptus and I. angustus were placed in a clade with some other species of the subgenera Pholeoixodes and Ixodiopsis. In addition, individuals of I. sculptus from Saskatchewan (Canada) and Colorado (USA) did not form a monophyletic clade, suggesting the possible existence of cryptic species.
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http://dx.doi.org/10.1016/j.mcp.2014.02.001DOI Listing
August 2014

Discovery of novel Rickettsiella spp. in ixodid ticks from Western Canada.

Appl Environ Microbiol 2014 Feb 13;80(4):1403-10. Epub 2013 Dec 13.

Department of Biology, University of Saskatchewan, Saskatoon, Saskatchewan, Canada.

The genomic DNA from four species of ixodid ticks in western Canada was tested for the presence of Rickettsiella by PCR analyses targeting the 16S rRNA gene. Eighty-eight percent of the Ixodes angustus (n = 270), 43% of the I. sculptus (n = 61), and 4% of the I. kingi (n = 93) individuals examined were PCR positive for Rickettsiella, whereas there was no evidence for the presence of Rickettsiella in Dermacentor andersoni (n = 45). Three different single-strand conformation polymorphism profiles of the 16S rRNA gene were detected among amplicons derived from Rickettsiella-positive ticks, each corresponding to a different sequence type. Furthermore, each sequence type was associated with a different tick species. Phylogenetic analyses of sequence data of the 16S rRNA gene and three other genes (rpsA, gidA, and sucB) revealed that all three sequence types were placed in a clade that contained species and pathotypes of the genus Rickettsiella. The bacterium in I. kingi represented the sister taxon to the Rickettsiella in I. sculptus, and both formed a clade with Rickettsiella grylli from crickets (Gryllus bimaculatus) and "R. ixodidis" from I. woodi. In contrast, the Rickettsiella in I. angustus was not a member of this clade but was placed external to the clade comprising the pathotypes of R. popilliae. The results indicate the existence of at least two new species of Rickettsiella: one in I. angustus and another in I. kingi and I. sculptus. However, the Rickettsiella strains in I. kingi and I. sculptus may also represent different species because each had unique sequences for all four genes.
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http://dx.doi.org/10.1128/AEM.03564-13DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3911054PMC
February 2014
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