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Equine veterinary journal2025; 58(2); 508-522; doi: 10.1111/evj.70120

Enhanced detection of equine strongyles: Insights from morphological and nemabiome metabarcoding approaches in northern Iran.

Abstract: Strongyles pose significant health concerns for equids globally. Strongyles, comprising over 60 species, can lead to severe morbidity and mortality, with Strongylus vulgaris posing higher risks due to its migratory behaviour. Routine diagnostic methods, such as faecal egg counts, lack species-level resolution, while traditional morphological techniques require advanced expertise. DNA metabarcoding offers a high-throughput alternative. Objective: To characterise the diversity of strongyles infecting horses in northern Iran and evaluate how age, sex, diagnostic methods and host population influence community composition. Methods: Cross-sectional. Methods: Strongyle communities were studied across four locations. At two farms, subsets of horses were analysed either by morphological identification of adult worms or by ITS2 metabarcoding of larval cultures. Morphological identification was performed on 1476 adult worms recovered from 23 horses at two farms (Rezvanshahr and Gisum). In parallel, ITS2 nemabiome metabarcoding was applied to pools of ~2500 L3 larvae from faeces of 25 untreated horses. Community composition was analysed using dissimilarity indices (Jaccard, Bray-Curtis), PERMANOVA and generalised linear models to assess the effects of farm, method, age and sex. Results: Thirty-three species were detected across both methods. DNA metabarcoding identified more species and 11 species were recorded in Iran for the first time. Strongyle community composition varied significantly among locations, including between resident and non-resident horses at the riding club, and between diagnostic methods. Neither horse age nor sex explained variation. S. vulgaris was prevalent across the majority of locations, potentially due to inconsistent treatment. Conclusions: Morphological and nemabiome identifications were conducted on different subsets of horses in the same location, precluding direct within-individual comparisons. The study relied on owner-reported information about horse characteristics and management practices. Conclusions: These findings provide new insights into strongyle diversity in northern Iran and highlight the value of molecular diagnostics for equine parasite surveillance and control.
© 2025 The Author(s). Equine Veterinary Journal published by John Wiley & Sons Ltd on behalf of EVJ Ltd.
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Publication Date: 2025-11-29 PubMed ID: 41316832PubMed Central: PMC12892384DOI: 10.1111/evj.70120Google Scholar: Lookup
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APA
Mohtasebi S, Ahn S, Karimi M, Saberi M, Gilleard JS, Poissant J. (2025). Enhanced detection of equine strongyles: Insights from morphological and nemabiome metabarcoding approaches in northern Iran. Equine Vet J, 58(2), 508-522. https://doi.org/10.1111/evj.70120

Publication

Equine veterinary journal
ISSN: 2042-3306
NlmUniqueID: 0173320
Country: United States
Language: English
Volume: 58
Issue: 2
Pages: 508-522

Researcher Affiliations

Mohtasebi, Sina
  • Faculty of Veterinary Medicine, University of Calgary, Calgary, Alberta, Canada.
Ahn, Sangwook
  • Faculty of Veterinary Medicine, University of Calgary, Calgary, Alberta, Canada.
Karimi, Mahan
  • Department of Medical Parasitology and Mycology, School of Medicine, Guilan University of Medical Sciences, Rasht, Iran.
Saberi, Mohammad
  • Department of Medical Parasitology and Mycology, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran.
Gilleard, John S
  • Faculty of Veterinary Medicine, University of Calgary, Calgary, Alberta, Canada.
Poissant, Jocelyn
  • Faculty of Veterinary Medicine, University of Calgary, Calgary, Alberta, Canada.

MeSH Terms

  • Animals
  • Horses
  • Iran / epidemiology
  • DNA Barcoding, Taxonomic / veterinary
  • Male
  • Female
  • Cross-Sectional Studies
  • Strongyle Infections, Equine / parasitology
  • Strongyle Infections, Equine / epidemiology
  • Strongyle Infections, Equine / diagnosis
  • Feces / parasitology
  • Strongylus / genetics
  • Strongylus / classification

Grant Funding

  • Margaret Gunn Endowment for Animal Health Research
  • University of Calgary Faculty of Veterinary Medicine Clinical Research Fund
  • Zoetis Investment in Innovation Fund
  • Alberta Graduate Excellence Scholarship
  • University of Calgary Provost's Doctoral Scholarship

Conflict of Interest Statement

The authors declare no conflicts of interest.

References

This article includes 61 references
  1. Khan MA, Roohi N, Rana MA. Strongylosis in equines: a review. J Anim Plant Sci. 2015;25:1–9.
  2. nOchigbo GO, Ahn S, Belhumeur KA, Poissant J, Rosa BV. Nemabiome sequencing reveals seasonal and age associated patterns of strongyle infection and high prevalence of in Alberta feral horses. Int J Parasitol Parasites Wildl. 2025;28:101091.
    pmc: PMC12167826pubmed: 40524829
  3. nRoy E, Hoste H, Beveridge I. The effects of concurrent experimental infections of sheep with Trichostrongylus colubriformis and on nematode distributions, numbers and on pathological changes. Parasite. 2004;11(3):293–300.n
    pubmed: 15490754
  4. Gordon HM, Whitlock H. A new technique for counting nematode eggs in sheep faeces. J Counc Sci Ind Res. 1939;12:50–52.
  5. nDomshy KA, Whitehead AE, Poissant J, Goldsmith DA, Legge C, Knight CG, et al. A retrospective study of the prevalence in equine postmortems of cranial mesenteric arteritis caused by in Alberta (2010 to 2022). Can Vet J. 2024;65(6):587–593.n
    pmc: PMC11132149pubmed: 38827589
  6. McCraw B, Slocombe J. Early development of and pathology associated with Strongylus edentatus. Can J Comp Med. 1974;38(2):124–138.
    pmc: PMC1319985pubmed: 4274818
  7. nMcCraw B, Slocombe J. n: development and pathological effects in the equine host. Can J Comp Med. 1985;49(4):372–383.n
    pmc: PMC1236195pubmed: 4075237
  8. Bull K, Hodgkinson J, Allen K, Poissant J, Peachey L. Quantitative DNA metabarcoding reveals species composition of a macrocyclic lactone and pyrantel resistant cyathostomin population in the UK. Int J Parasitol Drugs Drug Resist. 2025;27:100576.
    pmc: PMC11762968pubmed: 39778419
  9. Kotze AC, Gilleard JS, Doyle SR, Prichard RK. Challenges and opportunities for the adoption of molecular diagnostics for anthelmintic resistance. Int J Parasitol Drugs Drug Resist. 2020;14:264–273.
    pmc: PMC7726450pubmed: 33307336
  10. Schmitz JE, Stratton CW, Persing DH, Tang Y‐W. Forty years of molecular diagnostics for infectious diseases. J Clin Microbiol. 2022;60(10):e02446.
    pmc: PMC9580468pubmed: 35852340
  11. Verweij JJ. Application of PCR‐based methods for diagnosis of intestinal parasitic infections in the clinical laboratory. Parasitology. 2014;141(14):1863–1872.
    pubmed: 24780241
  12. 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(12):e0143559.
    pmc: PMC4668017pubmed: 26630572
  13. Miller ML, Rota C, Welsh A. Transforming gastrointestinal helminth parasite identification in vertebrate hosts with metabarcoding: a systematic review. Parasit Vectors. 2024;17(1):311.
    pmc: PMC11265005pubmed: 39030625
  14. Halvarsson P, Höglund J. Sheep nemabiome diversity and its response to anthelmintic treatment in Swedish sheep herds. Parasit Vectors. 2021;14:1–12.
    pmc: PMC7890823pubmed: 33602321
  15. Poissant J, Gavriliuc S, Bellaw J, Redman EM, Avramenko RW, Robinson D, et al. A repeatable and quantitative DNA metabarcoding assay to characterize mixed strongyle infections in horses. Int J Parasitol. 2021;51(2–3):183–192.
    pubmed: 33242465
  16. Pafčo B, Čížková D, Kreisinger J, Hasegawa H, Vallo P, Shutt K, et al. Metabarcoding analysis of strongylid nematode diversity in two sympatric primate species. Sci Rep. 2018;8(1):5933.
    pmc: PMC5897349pubmed: 29651122
  17. Davey ML, Utaaker KS, Fossøy F. Characterizing parasitic nematode faunas in faeces and soil using DNA metabarcoding. Parasit Vectors. 2021;14(1):422.
    pmc: PMC8380370pubmed: 34419166
  18. Beaumelle C, Redman E, Verheyden H, Jacquiet P, Bégoc N, Veyssière F, et al. Generalist nematodes dominate the nemabiome of roe deer in sympatry with sheep at a regional level. Int J Parasitol. 2022;52(12):751–761.
    pubmed: 36183847
  19. Nielsen MK, Reinemeyer CR. Handbook of equine parasite control. Hoboken, NJ: John Wiley & Sons; 2018.
  20. Lichtenfels JR, Kharchenko VA, Dvojnos GM. Illustrated identification keys to strongylid parasites (Strongylidae: Nematoda) of horses, zebras and asses (Equidae). Vet Parasitol. 2008;156(1–2):4–161.
    pubmed: 18603375
  21. nDuncan JL. n infection in the horse: University of Glasgow (United Kingdom). 1973.
  22. Corning S. Equine cyathostomins: a review of biology, clinical significance and therapy. Parasit Vectors. 2009;2(Suppl 2):S1.
    pmc: PMC2751837pubmed: 19778462
  23. Nielsen M. Anthelmintic resistance in equine nematodes: current status and emerging trends. Int J Parasitol Drugs Drug Resist. 2022;20:76–88.
    pmc: PMC9630620pubmed: 36342004
  24. Nielsen MK. What makes a good fecal egg count technique? Vet Parasitol. 2021;296:109509.
    pubmed: 34218175
  25. 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. Parasit Vectors. 2020;13:1–15.
    pmc: PMC7552500pubmed: 33046130
  26. Russell A. The development of helminthiasis in thoroughbred foals. J Comp Pathol Ther. 1948;58:107–127.
    pubmed: 18861669
  27. Abbas G, Ghafar A, Bauquier J, Beasley A, Ling E, Gauci CG, et al. Prevalence and diversity of ascarid and strongylid nematodes in Australian thoroughbred horses using next‐generation sequencing and bioinformatic tools. Vet Parasitol. 2023;323:110048.
    pubmed: 37844388
  28. Hamad MH, Islam SI, Jitsamai W, Chinkangsadarn T, Naraporn D, Ouisuwan S, et al. Patterns of equine small strongyle species infection after ivermectin intervention in Thailand: egg reappearance period and nemabiome metabarcoding approach. Animals. 2024;14(4):574.
    pmc: PMC10886017pubmed: 38396542
  29. Sargison N, Chambers A, Chaudhry U, Júnior LC, Doyle SR, Ehimiyein A, et al. 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(12):763–774.
    pubmed: 36208676
  30. Sazmand A, Bahari A, Papi S, Otranto D. Parasitic diseases of equids in Iran (1931–2020): a literature review. Parasit Vectors. 2020;13:1–19.
    pmc: PMC7676409pubmed: 33213507
  31. nBorji H, Moosavi Z, Ahmadi F. Cranial mesenteric arterial obstruction due to larvae in a donkey (). Iran J Parasitol. 2014;9(3):441–444.n
    pmc: PMC4316578pubmed: 25678931
  32. Eslami A, Bokai S, Tabatabai V. Equine parasites in Iran. J Equine Vet Sci. 2005;25(4):143–144.
  33. Tolliver SC. A practical method of identification of the North American cyathostomes (small strongyles) in equids in Kentucky: University of Kentucky, Department of Veterinary Science Lexington. 2000.
  34. Debeffe L, Mcloughlin PD, Medill SA, Stewart K, Andres D, Shury T, et al. Negative covariance between parasite load and body condition in a population of feral horses. Parasitology. 2016;143(8):983–997.
    pubmed: 27046508
  35. Dunn A. Veterinary helminthology. London: William Heinemann Medical Books Ltd; 1978.
  36. 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(10):2525–2526.
    pmc: PMC309567pubmed: 8506152
  37. Workentine ML, Chen R, Zhu S, Gavriliuc S, Shaw N, Rijke J, et al. A database for ITS2 sequences from nematodes. BMC Genet. 2020;21(1):74.
    pmc: PMC7350610pubmed: 32650716
  38. Diekmann I, Krücken J, Kuzmina TA, Bredtmann CM, Louro M, Kharchenko VA, et al. Comparative phylogenetic and sequence identity analysis of internal transcribed spacer 2 and cytochrome c oxidase subunit I as DNA barcode markers for the most common equine Strongylidae species. Infect Genet Evol. 2025;129:105729.
    pubmed: 39955017
  39. Newton L, Chilton N, Beveridge I, Hoste H, Nansen P, Gasser R. Genetic markers for strongylid nematodes of livestock defined by PCR‐based restriction analysis of spacer rDNA. Acta Trop. 1998;69(1):1–15.
    pubmed: 9588237
  40. Okonechnikov K, Golosova O, Fursov M, UGENE Team . Unipro UGENE: a unified bioinformatics toolkit. Bioinformatics. 2012;28(8):1166–1167.
    pubmed: 22368248
  41. Nielsen MK, Steuer AE, Anderson HP, Gavriliuc S, Carpenter AB, Redman EM, et al. 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(12):787–798.
    pubmed: 36244428
  42. Ahn S, Redman EM, Gavriliuc S, Bellaw J, Gilleard JS, McLoughlin PD, et al. Mixed strongyle parasite infections vary across host age and space in a population of feral horses. Parasitology. 2024;151:1299–1316.
    pmc: PMC11894017pubmed: 39663810
  43. Oksanen J, Kindt R, Legendre P, O'Hara B, Stevens MHH, Oksanen MJ, et al. The vegan package. Community Ecology. 2007;10(631–637):719.
  44. Brooks M, Bolker B, Kristensen K, Maechler M, Magnusson A, McGillycuddy M. Package ‘glmmtmb’. R Packag Vers 1,1; 2023.
  45. Lenth R. emmeans: Estimated marginal means, aka least‐squares means. R package version 1.7. 2; 2022.
  46. Abbas G, Ghafar A, Beasley A, Stevenson MA, Bauquier J, Koehler AV, et al. Understanding temporal and spatial distribution of intestinal nematodes of horses using faecal egg counts and DNA metabarcoding. Vet Parasitol. 2024;325:110094.
    pubmed: 38091893
  47. Halvarsson P, Grandi G, Hägglund S, Höglund J. Gastrointestinal parasite community structure in horses after the introduction of selective anthelmintic treatment strategies. Vet Parasitol. 2024;326:110111.
    pubmed: 38218052
  48. Chapman M, Kearney M, Klei T. Equine cyathostome populations: accuracy of species composition estimations. Vet Parasitol. 2003;116(1):15–21.
    pubmed: 14519323
  49. Lind EO, Eysker M, Nilsson O, Uggla A, Höglund J. Expulsion of small strongyle nematodes (cyathostomin spp) following deworming of horses on a stud farm in Sweden. Vet Parasitol. 2003;115(4):289–299.
    pubmed: 12944042
  50. Tavassoli M, Dalir‐Naghadeh B, Esmaeili‐Sani S. Prevalence of gastrointestinal parasites in working horses. Pol J Vet Sci. 2010;13(2):319–324.
    pubmed: 20731187
  51. nHarvey AM, Meggiolaro MN, Hall E, Watts ET, Ramp D, Šlapeta J. Wild horse populations in south‐east Australia have a high prevalence of and may act as a reservoir of infection for domestic horses. Int J Parasitol Parasites Wildl. 2019;8:156–163.n
    pmc: PMC6378629pubmed: 30815358
  52. Nielsen MK, Baptiste KE, Tolliver S, Collins S, Lyons E. 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(1–2):77–84.
    pubmed: 20850927
  53. nNielsen M, Vidyashankar A, Gravatte H, Bellaw J, Lyons E, Andersen U. Development of ‐specific serum antibodies in naturally infected foals. Vet Parasitol. 2014;200(3–4):265–270.n
    pubmed: 24433851
  54. Kenealy JA, Steuer AE. Reviving a tradition: the development of Strongylus vulgaris in larval culture. Vet Parasitol. 2021;300:109619.
    pubmed: 34839176
  55. Louro M, Kuzmina TA, Bredtmann CM, Diekmann I, de Carvalho LMM, von Samson‐Himmelstjerna G, et al. Genetic variability, cryptic species and phylogenetic relationship of six cyathostomin species based on mitochondrial and nuclear sequences. Sci Rep. 2021;11(1):8245.
    pmc: PMC8050097pubmed: 33859247
  56. nMohtasebi S, Ahn S, Rosa B, Moyes K, Kuzmina T, Gilleard J, et al. First record of (Nematoda: Strongylidae) in North America: morphological and molecular identification of a rare equine strongyle. J Helminthol. 2025;99:e35.n
    pubmed: 39988803
  57. Bradbury RS, Sapp SG, Potters I, Mathison BA, Frean J, Mewara A, et al. Where have all the diagnostic morphological parasitologists gone? J Clin Microbiol. 2022;60(11):e00986‐00922.
    pmc: PMC9667774pubmed: 36314793
  58. Avramenko RW, Bras A, Redman EM, Woodbury MR, Wagner B, Shury T, et al. High species diversity of trichostrongyle parasite communities within and between Western Canadian commercial and conservation bison herds revealed by nemabiome metabarcoding. Parasit Vectors. 2018;11:1–13.
    pmc: PMC5952520pubmed: 29764472
  59. Owen J, Slocombe D. Pathogenesis of helminths in equines. Vet Parasitol. 1985;18(2):139–153.
    pubmed: 2930935
  60. 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.
    pubmed: 27523938
  61. Sallé G, Kornaś S, Basiaga M. Equine strongyle communities are constrained by horse sex and species dipersal‐fecundity trade‐off. Parasit Vectors. 2018;11:1–11.
    pmc: PMC5930759pubmed: 29716644

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