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International journal for parasitology. Parasites and wildlife2025; 27; 101091; doi: 10.1016/j.ijppaw.2025.101091

Nemabiome sequencing reveals seasonal and age associated patterns of strongyle infection and high prevalence of Strongylus vulgaris in Alberta feral horses.

Abstract: Unmanaged feral horses, naïve to dewormers, offer a unique opportunity to study natural communities of equine parasites. These communities may include parasites that are rare in managed populations, and these may be transmitted to domestic horses in areas where there is contact between feral and domestic equine populations. There have been only a few studies of gastrointestinal parasite populations in horses, and very few from North American equine populations. This study aimed to gain insights into parasite biology through identification of the strongyle parasite species infecting feral horses in Alberta, Canada, and to test for species-specific infection patterns across season and horse age. Fecal samples (N = 149) were collected from unique individuals in the Sundre Equine Management Zone (EMZ), Alberta, across two years: 2021 (N = 62) and 2022 (N = 87). In 2021, samples were collected in summer (N = 31; 8 foals, 5 subadults, 18 adults) and fall (N = 31; 5 foals, 1 subadult, 25 adults). In 2022, samples were collected in spring (N = 36; 4 subadults, 32 adults), summer (N = 41; 4 foals, 8 subadults, 29 adults), and fall (N = 20; 1 foal, 2 subadults, 17 adults). Fecal egg counts showed that these horses shed high numbers of strongyle eggs relative to domestic horse populations (mean = 1337.01 ± 961.81 epg), and nemabiome analyses identified a total of 34 strongyle species. Species richness and aggregate strongyle FECs were highest in subadults and during the summer, while lowest in foals and during the fall. There was a high prevalence of large strongyle species, especially (85.91 %), with strongyle species-specific prevalence and FECs strongly associated with age and season. Understanding the factors driving species-specific parasite infection provides important information on strongyle parasite ecology and may aid the development of targeted parasite control strategies.
Publication Date: 2025-05-28 PubMed ID: 40524829PubMed Central: PMC12167826DOI: 10.1016/j.ijppaw.2025.101091Google Scholar: Lookup
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  • Journal Article

Summary

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This study delves into the high prevalence of strongyle parasite species, notably Strongylus vulgaris, in Alberta’s feral horse populations. Researchers identified species-specific infection patterns grounded in season and horse age, thus facilitating an improved understanding of strongyle parasite ecology, which may prove beneficial for formulating targeted parasite control schemes.

Study Background

  • Feral horses, devoid of dewormer treatment, provide a unique opportunity for investigating the natural community of equine parasites. This study aims to scrutinize the various species of strongyle parasites infecting feral horses in Alberta, Canada. Such an analysis allows for subsequent detection of species-specific infection patterns based on season and horse age.
  • Despite the rarity of gastrointestinal parasite studies in horses, and particularly in North American equine populations, an understanding of these parasites is important because they may be transferred to domestic horse populations, particularly in regions where feral and domestic populations interact.

Data Collection and Findings

  • Over two years—2021 and 2022— fecal samples were collected from unique individuals in the Sundre Equine Management Zone in Alberta. The samples were gathered at different times of the year (spring, summer, and fall) and from horses of varying ages (foals, subadults, and adults).
  • Fecal egg count measurements showed that these horses shed high numbers of strongyle eggs relative to domestic horse populations. In total, researchers identified 34 distinct strongyle species through nemabiome analysis.
  • In terms of species richness and strongyle fecal egg counts, the results were highest in subadults and during the summer seasons. Conversely, the results were lowest in foals and during the fall seasons.

Implications of the Study

  • The study established a high prevalence of large strongyle species, specifically Strongylus vulgaris (85.91 %). The prevalence and fecal egg counts of strongyle species were strongly associated with the age and season, indicating a season and age specific mechanism of infection.
  • Understanding the factors that drive species-specific parasite infections can provide significant information on strongyle parasite ecology. Such knowledge can be essential for developing targeted parasite control strategies, protecting both feral and domestic horse populations.

Cite This Article

APA
Ochigbo GO, Ahn S, Belhumeur KA, Poissant J, Rosa BV. (2025). Nemabiome sequencing reveals seasonal and age associated patterns of strongyle infection and high prevalence of Strongylus vulgaris in Alberta feral horses. Int J Parasitol Parasites Wildl, 27, 101091. https://doi.org/10.1016/j.ijppaw.2025.101091

Publication

ISSN: 2213-2244
NlmUniqueID: 101599824
Country: England
Language: English
Volume: 27
Pages: 101091
PII: 101091

Researcher Affiliations

Ochigbo, Grace Onyeche
  • Faculty of Veterinary Medicine, University of Calgary, 3280 Hospital Drive NW, Calgary, AB, T2N 4Z6, Canada.
Ahn, Sangwook
  • Faculty of Veterinary Medicine, University of Calgary, 3280 Hospital Drive NW, Calgary, AB, T2N 4Z6, Canada.
Belhumeur, Kobe Albert
  • Faculty of Science, University of Calgary, 2500 University Drive NW, Calgary, AB, T2N 1N4, Canada.
Poissant, Jocelyn
  • Faculty of Veterinary Medicine, University of Calgary, 3280 Hospital Drive NW, Calgary, AB, T2N 4Z6, Canada.
Rosa, Brielle Vastola
  • Faculty of Veterinary Medicine, University of Calgary, 3280 Hospital Drive NW, Calgary, AB, T2N 4Z6, Canada.

Conflict of Interest Statement

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

References

This article includes 55 references
  1. Abbas G, Ghafar A, Bauquier J, Beasley A, Ling E, Gauci CG, El-Hage C, Wilkes EJA, McConnell E, Carrigan P, Cudmore L, Hurley J, Beveridge I, Nielsen MK, Stevenson MA, Jacobson C, Hughes KJ, Jabbar A. Prevalence and diversity of ascarid and strongylid nematodes in Australian Thoroughbred horses using next-generation sequencing and bioinformatic tools.. Vet. Parasitol. 2023;323.
    doi: 10.1016/j.vetpar.2023.110048pubmed: 37844388google scholar: lookup
  2. Ahn S, Redman EM, Gavriliuc S, Bellaw J, Gilleard JS, McLoughlin PD, Poissant J. Mixed strongyle parasite infections vary across host age and space in a population of feral horses.. Parasitology (Lond.) 2024;151:1299–1316.
    doi: 10.1017/S0031182024001185pmc: PMC11894017pubmed: 39663810google scholar: lookup
  3. Avramenko RW, Redman EM, Lewis R, Yazwinski TA, Wasmuth JD, Gilleard JS. Exploring the gastrointestinal “nemabiome”: deep amplicon sequencing to quantify the species composition of parasitic nematode communities.. PLoS One 2015;10.
  4. Bellaw JL, Nielsen MK. Meta-analysis of cyathostomin species-specific prevalence and relative abundance in domestic horses from 1975–2020: emphasis on geographical region and specimen collection method.. Parasites Vectors 2020;13:509.
    doi: 10.1186/s13071-020-04396-5pmc: PMC7552500pubmed: 33046130google scholar: lookup
  5. Brooks ME, Kristensen K, Van Benthem KJ, Magnusson A, Berg CW, Nielsen A, Skaug HJ, Mächler M, Bolker BM. glmmTMB balances speed and flexibility among packages for zero-inflated generalized linear mixed modeling.. Rom. Jahrb. 2017;9:378–400.
  6. Bull KE, Hodgkinson J, Allen K, Poissant J, Peachey LE. Quantitative DNA metabarcoding reveals species composition of a macrocyclic lactone and pyrantel resistant cyathostomin population in the UK.. Int J Parasitol Drugs Drug Resist. 2024.
  7. Callahan BJ, Mcmurdie PJ, Rosen MJ, Han AW, Johnson AJA, Holmes SP. DADA2: high-resolution sample inference from Illumina amplicon data.. Nat. Methods 2016;13:581–587.
    doi: 10.1038/nmeth.3869pmc: PMC4927377pubmed: 27214047google scholar: lookup
  8. Courtot É, Boisseau M, Dhorne-Pollet S, Serreau D, Gesbert A, Reigner F, Basiaga M, Kuzmina T, Lluch J, Annonay G, Kuchly C, Diekmann I, Krücken J, von Samson-Himmelstjerna G, Mach N, Sallé G. Comparison of two molecular barcodes for the study of equine strongylid communities with amplicon sequencing.. PeerJ 2023;11:1–29.
    doi: 10.7717/peerj.15124pmc: PMC10105562pubmed: 37070089google scholar: lookup
  9. Debeffe L, McLoughlin PD, Medill SA, Stewart K, Andres D, Shury T, Wagner B, Jenkins E, Gilleard JS, Poissant J. Negative covariance between parasite load and body condition in a population of feral horses.. Parasitology (Lond.) 2016;143:983–997.
    doi: 10.1017/S0031182016000408pubmed: 27046508google scholar: lookup
  10. Domshy KA, Whitehead AE, Poissant J, Goldsmith DA, Legge C, Knight CG, Zachar EK, Loch SS, Davies JL. A retrospective study of the prevalence in equine postmortems of cranial mesenteric arteritis caused by Strongylus vulgaris in Alberta (2010 to 2022). CVJ (Can. Vet. J.) 2024;65:587–593.
    pmc: PMC11132149pubmed: 38827589
  11. Ezenwa VO, Stefan Ekernas L, Creel S. Unravelling complex associations between testosterone and parasite infection in the wild.. Funct. Ecol. 2012;26:123–133.
  12. Gasser RB, Chilton NB, Hoste H, Beveridge I. Rapid sequencing of rDNA from single worms and eggs of parasitic helminths.. Nucleic Acids Res. 1993;21:2525–2526.
    doi: 10.1093/nar/21.10.2525pmc: PMC309567pubmed: 8506152google scholar: lookup
  13. Girard TL, Bork EW, Nielsen SE, Alexander MJ. Seasonal variation in habitat selection by free-ranging feral horses within Alberta's forest reserve.. Rangel. Ecol. Manag. 2013;66:428–437.
    doi: 10.2111/REM-D-12-00081.1google scholar: lookup
  14. Government of Alberta Feral horse minimum count. 2023. https://open.alberta.ca/dataset/ac45bc28-f2cb-400d-9a85-1b0fb02ac23a/resource/b21419ce-a96e-415a-9a1e-c104602f4561/download/fp-feral-horse-minimum-count-map-2023-09.pdf 5.14.25)
  15. Hamad MH, Jitsamai W, Chinkangsadarn T, Ngangam TS, Wattanapornpilom T, Naraporn D, Ouisuwan S, Taweethavonsawat P. Prevalence, risk factors, and species diversity of strongylid nematodes in domesticated Thai horses: insights from ITS-2 rDNA metabarcoding.. Parasitol. Res. 2024;123:410.
    doi: 10.1007/s00436-024-08438-0pubmed: 39688721google scholar: lookup
  16. Harvey AM, Meggiolaro MN, Hall E, Watts ET, Ramp D, Šlapeta J. Wild horse populations in south-east Australia have a high prevalence of Strongylus vulgaris and may act as a reservoir of infection for domestic horses.. Int J Parasitol Parasites Wildl. 2019;8:156–163.
  17. Jenkins E, Backwell AL, Bellaw JL, Colpitts J, Liboiron A, McRuer D, Medill S, Parker S, Shury T, Smith M, Tschritter C, Wagner B, Poissant J, McLoughlin P. Not playing by the rules: unusual patterns in the epidemiology of parasites in a natural population of feral horses (Equus caballus) on Sable Island, Canada.. Int J Parasitol Parasites Wildl. 2020;11:183–190.
  18. Kaplan RM, Denwood MJ, Nielsen MK, Thamsborg SM, Torgerson PR, Gilleard JS, Dobson RJ, Vercruysse J, Levecke B. World Association for the Advancement of Veterinary Parasitology (W.A.A.V.P.) guideline for diagnosing anthelmintic resistance using the faecal egg count reduction test in ruminants, horses and swine.. Vet. Parasitol. 2023;318.
    doi: 10.1016/j.vetpar.2023.109936pubmed: 37121092google scholar: lookup
  19. Khan MA, Roohi N, Rana MA. Strongylosis in equines: a review.. J. Animal Plant Sci. 2015;25:1–9.
  20. Kuzmina TA, Lyons ET, Tolliver SC, Dzeverin II, Kharchenko VA. Fecundity of various species of strongylids (Nematoda: strongylidae)- parasites of domestic horses.. Parasitol. Res. 2012;111:2265–2271.
    doi: 10.1007/s00436-012-3077-5pubmed: 22903448google scholar: lookup
  21. Kuzmina TA, Dzeverin I, Kharchenko VA. Strongylids in domestic horses: influence of horse age, breed and deworming programs on the strongyle parasite community.. Vet. Parasitol. 2016;227:56–63.
    doi: 10.1016/j.vetpar.2016.07.024pubmed: 27523938google scholar: lookup
  22. Leathwick DM, Sauermann CW, Reinemeyer CR, Nielsen MK. A model for the dynamics of the parasitic stages of equine cyathostomins.. Vet. Parasitol. 2019;268:53–60.
    doi: 10.1016/j.vetpar.2019.03.004pubmed: 30981306google scholar: lookup
  23. Levecke B, Rinaldi L, Charlier J, Maurelli MP, Bosco A, Vercruysse J, Cringoli G. The bias, accuracy and precision of faecal egg count reduction test results in cattle using McMaster, Cornell-Wisconsin and FLOTAC egg counting methods.. Vet. Parasitol. 2012;188:194–199.
    doi: 10.1016/j.vetpar.2012.03.017pubmed: 22503038google scholar: lookup
  24. Lichtenfels JR, Kharchenko VA, Dvojnos GM. Illustrated identification keys to strongylid parasites (strongylidae: nematoda) of horses, zebras and asses (Equidae). Vet. Parasitol. 2008;156:4–161.
    doi: 10.1016/j.vetpar.2008.04.026pubmed: 18603375google scholar: lookup
  25. Love S, Murphy D, Mellor D. Pathogenicity of cyathostome infection.. Vet. Parasitol. 1999;85:113–122.
    doi: 10.1016/S0304-4017(99)00092-8pubmed: 10485358google scholar: lookup
  26. Malsa J, Boudesocque-Delaye L, Wimel L, Auclair-Ronzaud J, Dumont B, Mach N, Reigner F, Guégnard F, Chereau A, Serreau D, Théry-Koné I, Sallé G, Fleurance G. Chicory (Cichorium intybus) reduces cyathostomin egg excretion and larval development in grazing horses.. Int J Parasitol Drugs Drug Resist. 2024;24.
  27. McCraw BM, Slocombe JOD. Strongylus vulgaris in the horse: a review.. CVJ (Can. Vet. J.) 1976;17:150–157.
    pmc: PMC1697226pubmed: 779947
  28. McCraw BM, Slocombe JOD. Strongylus edentatus: development and lesions from ten weeks postinfection to patency.. J. Compl. Med. 1978;42:340–356.
    pmc: PMC1277649pubmed: 688075
  29. Mfitilodze MW, Hutchinson GW. Development and survival of free-living stages of equine strongyles under laboratory conditions.. Vet. Parasitol. 1987;23:121–133.
    doi: 10.1016/0304-4017(87)90030-6pubmed: 3564339google scholar: lookup
  30. Mitchell CJ, O'Sullivan CM, Pinloche E, Wilkinson T, Morphew RM, McEwan NR. Using next-generation sequencing to determine diversity of horse intestinal worms: identifying the equine ʼnemabiome’.. J. Equine Sci. 2019;30:1–5.
    doi: 10.1294/jes.30.1pmc: PMC6445754pubmed: 30944540google scholar: lookup
  31. Murphy D, Keane MP, Chandler KJ, Goulding R. Cyathostome-associated disease in the horse: investigation and management of four cases.. Equine Vet. Educ. 1997;9:247–252.
  32. Nielsen MK. Evidence-based considerations for control of Parascaris spp. infections in horses.. Equine Vet. Educ. 2016;28:224–231.
    doi: 10.1111/eve.12536google scholar: lookup
  33. Nielsen MK. What makes a good fecal egg count technique?. Vet. Parasitol. 2021;296.
    doi: 10.1016/j.vetpar.2021.109509pubmed: 34218175google scholar: lookup
  34. Nielsen MK. Parasite faecal egg counts in equine veterinary practice.. Equine Vet. Educ. 2022;34:584–591.
    doi: 10.1111/eve.13548google scholar: lookup
  35. Nielsen MK, Kaplan RM, Thamsborg SM, Monrad J, Olsen SN. Climatic influences on development and survival of free-living stages of equine strongyles: implications for worm control strategies and managing anthelmintic resistance.. TVJ 2007;174:23–32.
    doi: 10.1016/j.tvjl.2006.05.009pubmed: 16815051google scholar: lookup
  36. Nielsen MK, Baptiste KE, Tolliver SC, Collins SS, Lyons ET. Analysis of multiyear studies in horses in Kentucky to ascertain whether counts of eggs and larvae per gram of feces are reliable indicators of numbers of strongyles and ascarids present.. Vet. Parasitol. 2010;174:77–84.
    doi: 10.1016/j.vetpar.2010.08.007pubmed: 20850927google scholar: lookup
  37. Nielsen MK, Steuer AE, Anderson HP, Gavriliuc S, Carpenter AB, Redman EM, Gilleard JS, Reinemeyer CR, Poissant J. Shortened egg reappearance periods of equine cyathostomins following ivermectin or moxidectin treatment: morphological and molecular investigation of efficacy and species composition.. Int. J. Parasitol. 2022;52:787–798.
    doi: 10.1016/j.ijpara.2022.09.003pubmed: 36244428google scholar: lookup
  38. Noel ML, Scare JA, Bellaw JL, Nielsen MK. Accuracy and precision of Mini-FLOTAC and McMaster techniques for determining equine strongyle egg counts.. J. Equine Vet. Sci. 2017;48:182–187.e1.
  39. Oksanen J, Simpson GL, Blanchet GF, Kindt R, Legendre P, Minchin PR, O'Hara RB, Solymos P, Stevens MHH, Szoecs E, Wagner H, Barbour M, Bolker B, Borcard D, Carvalho G, Chirico M, De Caceres M, Durand S, Evangelista HBA, FitzJohn R, Friendly M, Furneaux B, Hannigan G, Hill MO, Lahti L, McGlinn D, Ouellette M-H, Cunha ER, Smith T, Stier A, Ter Braak CJF, Weedon J. vegan: an R package for community ecologists Retrieved.. 2022.
  40. Olanrewaju YA, Surajudeen MB, Akinyemi BT. Common plant bioactive components adopted in combating gastrointestinal nematodes in small ruminant – a review.. Agric. Sci. 2023;20:61–73.
    doi: 10.18690/agricsci.20.1.7google scholar: lookup
  41. Poissant J, Gavriliuc S, Bellaw JL, Redman EM, Avramenko RW, Robinson D, Workentine ML, Shury TK, Jenkins EJ, Mcloughlin PD, Nielsen MK, Gilleard JS. A repeatable and quantitative DNA metabarcoding assay to characterize mixed strongyle infections in horses.. Int. J. Parasitol. 2021;51:183–192.
    pubmed: 33242465
  42. Queiroz C, Levy M, Avramenko R, Redman E, Kearns K, Swain L, Silas H, Uehlinger F, Gilleard JS. The use of ITS-2 rDNA nemabiome metabarcoding to enhance anthelmintic resistance diagnosis and surveillance of ovine gastrointestinal nematodes.. Int J Parasitol Drugs Drug Resist. 2020;14:105–117.
  43. Redman E, Queiroz C, Bartley DJ, Levy M, Avramenko RW, Stuart J. Validation of ITS-2 rDNA nemabiome sequencing for ovine gastrointestinal nematodes and its application to a large scale survey of UK sheep farms.. Vet. Parasitol. 2019;275.
    doi: 10.1016/j.vetpar.2019.108933pubmed: 31606485google scholar: lookup
  44. Rendle D, Hughes K, Bowen M, Bull K, Cameron I, Furtado T, Peachey L, Sharpe L, Hodgkinson J. scp>BEVA</scp> primary care clinical guidelines: equine parasite control.. Equine Vet. J. 2024;56:392–423.
    doi: 10.1111/evj.14036pubmed: 38169127google scholar: lookup
  45. Roberts F, O'Sullivan P. Methods for egg counts and larval cultures for strongyles infesting the gastro-intestinal tract of cattle.. Aust. J. Agric. Res. 1950;1:99–103.
    doi: 10.1071/ar9500099google scholar: lookup
  46. Rodríguez-Hernández P, Reyes-Palomo C, Sanz-Fernández S, Rufino-Moya PJ, Zafra R, Martínez-Moreno FJ, Rodríguez-Estévez V, Díaz-Gaona C. Antiparasitic tannin-rich plants from the south of Europe for grazing livestock: a Review.. Animals 2023;13:201.
    doi: 10.3390/ani13020201pmc: PMC9855007pubmed: 36670741google scholar: lookup
  47. Rossanigo CE, Gruner L. Relative effect of temperature and moisture on the development of strongyle eggs to infective larvae in bovine pats in Argentina.. Vet. Parasitol. 1994;55:317–325.
    doi: 10.1016/0304-4017(94)90072-8pubmed: 7725625google scholar: lookup
  48. Round MC. The prepatent period of some horse nematodes determined by experimental infection.. J. Helminthol. 1969;43:185–192.
    doi: 10.1017/S0022149X00004016pubmed: 5381124google scholar: lookup
  49. Russell AF. The development of helminthiasis in thoroughbred foals.. J. Comp. Pathol. Ther. 1948;58:107–127.
    doi: 10.1016/s0368-1742(48)80009-3pubmed: 18861669google scholar: lookup
  50. Sallé G, Kornaś S, Basiaga M. Equine strongyle communities are constrained by horse sex and species dipersal-fecundity trade-off.. Parasites Vectors 2018;11:1–11.
    doi: 10.1186/s13071-018-2858-9pmc: PMC5930759pubmed: 29716644google scholar: lookup
  51. Sargison N, Chambers A, Chaudhry U, Costa Júnior L, Doyle SR, Ehimiyein A, Evans M, Jennings A, Kelly R, Sargison F, Sinclair M, Zahid O. Faecal egg counts and nemabiome metabarcoding highlight the genomic complexity of equine cyathostomin communities and provide insight into their dynamics in a Scottish native pony herd.. Int. J. Parasitol. 2022;52:763–774.
    doi: 10.1016/j.ijpara.2022.08.002pubmed: 36208676google scholar: lookup
  52. Slivinska K, Klich D, Yasynetska N, Żygowska M. The effects of seasonality and group size on fecal egg counts in wild Przewalski's horses (Equus ferus przewalskii , Poljakov, 1881) in the Chernobyl Exclusion Zone, Ukraine during 2014 – 2018.. Helminthologia 2020;57:314–321.
    doi: 10.2478/helm-2020-0042pmc: PMC7734672pubmed: 33364900google scholar: lookup
  53. . Veterinary Parasitology.. Wiley 2015.
    doi: 10.1002/9781119073680google scholar: lookup
  54. Wood ELD, Matthews JB, Stephenson S, Slote M, Nussey DH. Variation in fecal egg counts in horses managed for conservation purposes: individual egg shedding consistency, age effects and seasonal variation.. Parasitology (Lond.) 2013;140:115–128.
    doi: 10.1017/S003118201200128Xpubmed: 22894917google scholar: lookup
  55. Workentine ML, Chen R, Zhu S, Gavriliuc S, Shaw N, Rijke J de, Redman EM, Avramenko RW, Wit J, Poissant J, Gilleard JS. A database for ITS2 sequences from nematodes.. BMC Genet. 2020;21:10–13.
    doi: 10.1186/s12863-020-00880-0pmc: PMC7350610pubmed: 32650716google scholar: lookup

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