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Veterinary parasitology2010; 174(1-2); 77-84; doi: 10.1016/j.vetpar.2010.08.007

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.

Abstract: Increasing levels of anthelmintic resistance in equine nematodes have led to recommendations of more sustainable anthelmintic treatment protocols with emphasis on parasite surveillance and diagnosis, rather than prophylactic calendar-based treatments. This requires knowledge of the diagnostic test performance of techniques for counts of eggs per gram of feces (EPG) as well as methods for culturing, counting and identifying third stage (L(3)) strongyle larvae per gram of feces (LPG). For horses, such information does not exist in the published literature. The aim of this study was to examine the relationship between worm count and fecal egg count (FEC) data for strongyle and Parascaris equorum infections as well as larval culture counts for diagnosing Strongylus spp. infections. Necropsy data from 693 horses used for critical or controlled tests, including information on total worm counts, fecal egg counts (FEC) and larval culture results collected at the University of Kentucky over a period of 50 years were analyzed. Sensitivity, specificity, positive and negative predictive values, and receiver operator characteristic (ROC) curves were generated for the larval cultures and ascarid egg counts. For the strongyle egg counts, potential FEC cutoff values for treatment were evaluated statistically by comparing the total strongyle worm counts below and above chosen cutoff values. All tests had high positive predictive values (>0.95), but moderate negative predictive values (<0.70). The negative predictive values of the larval counts were negatively affected by increasing egg count levels. Strongyle FEC cutoff values up to the level of 500 EPG yielded significantly higher strongyle worm counts in the treatment group, whereas no differences were found at higher cutoffs. This supports usage of cutoffs for treatment in the 0-500 EPG range. Altogether, the present study yields unique and useful information of widely used methods for parasite surveillance and diagnosis in equine establishments.
Copyright © 2010 Elsevier B.V. All rights reserved.
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Publication Date: 2010-08-17 PubMed ID: 20850927DOI: 10.1016/j.vetpar.2010.08.007Google Scholar: Lookup
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  • Journal Article

Summary

This research summary has been generated with artificial intelligence and may contain errors and omissions. Refer to the original study to confirm details provided. Submit correction.

The study examines the relationship between the number of worms in horses and the count of their eggs in faeces, with the aim to improve parasitic surveillance and diagnosis in equine care. The findings suggest that taking counts of eggs in faeces can indeed serve as a reliable method in diagnosing worm infections, provided the considered egg count falls within a certain range.

Background

  • This research is necessitated by increasing levels of resistance in equine nematodes to anthelmintic, the drugs used for their treatment. As a result, the treatment strategy has pivoted from prophylactic calendar-based treatments to more sustainable surveillance and diagnosis-centric treatments.
  • The study’s focus is on the efficiency of diagnostic tests for counts of eggs per gram of faeces (EPG) along with methods for counting and identifying strongyle larvae in faeces. The lack of such information on horses led to this research.
  • The study aims to understand the relationship between total worm count and fecal egg count for both strongyle and Parascaris equorum infections, and counts of cultured larvae for diagnosing Strongylus spp. infections.

Methodology

  • The study analysed data from 693 necropsies conducted over 50 years on horses at the University of Kentucky. The data contained information regarding total worm counts, fecal egg counts and results of larval culture.
  • Several measures of test effectiveness like sensitivity, specificity, positive and negative predictive values, and receiver operator characteristic (ROC) curves were generated for egg counts of ascarids and larval cultures.
  • Potential thresholds for treatment based on strongyle egg counts were also statistically evaluated by comparing total strongyle worm counts below and above the established values.

Findings

  • All tests had high positive predictive values (greater than 0.95); however, the negative predictive values were moderate (less than 0.70).
  • The study’s negative predictive values were affected negatively with increasing egg count levels.
  • Strongyle fecal egg count thresholds up to the level of 500 EPG resulted in significantly higher strongyle worm counts in horses needing treatment. No differences were found at higher thresholds.
  • This implies that for strongyle egg counts in the 0-500 EPG range, it is beneficial to use these counts for determining treatment.

Conclusion

  • The research provides unique information about the widely used methods for parasitic surveillance and diagnosis in horse establishments. It concludes that counts of eggs per gram of faeces can serve as a reliable diagnostic method for worm infections in horses, provided the egg count is in the considered range.

Cite This Article

APA
Nielsen MK, Baptiste KE, Tolliver SC, Collins SS, Lyons ET. (2010). 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, 174(1-2), 77-84. https://doi.org/10.1016/j.vetpar.2010.08.007

Publication

Veterinary parasitology
ISSN: 1873-2550
NlmUniqueID: 7602745
Country: Netherlands
Language: English
Volume: 174
Issue: 1-2
Pages: 77-84

Researcher Affiliations

Nielsen, M K
  • Department of Large Animal Sciences, Faculty of Life Sciences, University of Copenhagen, 5 Højbakkegård Alle, DK-2630 Taastrup, Denmark. mkn@life.ku.dk
Baptiste, K E
    Tolliver, S C
      Collins, S S
        Lyons, E T

          MeSH Terms

          • Animals
          • Ascaridida Infections / diagnosis
          • Ascaridida Infections / veterinary
          • Ascaridoidea
          • Feces / parasitology
          • Horse Diseases / diagnosis
          • Horse Diseases / parasitology
          • Horses
          • Kentucky
          • Larva
          • Parasite Egg Count / statistics & numerical data
          • Parasite Egg Count / veterinary
          • Strongyle Infections, Equine / diagnosis
          • Strongyloidea / isolation & purification

          Citations

          This article has been cited 45 times.
          1. Elghryani N, McOwan T, Mincher C, Duggan V, de Waal T. Estimating the Prevalence and Factors Affecting the Shedding of Helminth Eggs in Irish Equine Populations. Animals (Basel) 2023 Feb 7;13(4).
            doi: 10.3390/ani13040581pubmed: 36830368google scholar: lookup
          2. Boisseau M, Mach N, Basiaga M, Kuzmina T, Laugier C, Sallé G. Patterns of variation in equine strongyle community structure across age groups and gut compartments. Parasit Vectors 2023 Feb 11;16(1):64.
            doi: 10.1186/s13071-022-05645-5pubmed: 36765420google scholar: lookup
          3. Boelow H, Krücken J, von Samson-Himmelstjerna G. Epidemiological study on factors influencing the occurrence of helminth eggs in horses in Germany based on sent-in diagnostic samples. Parasitol Res 2023 Mar;122(3):749-767.
            doi: 10.1007/s00436-022-07765-4pubmed: 36627515google scholar: lookup
          4. Lynsdale CL, Seltmann MW, Mon NO, Aung HH, Nyein U, Htut W, Lahdenperä M, Lummaa V. Investigating associations between nematode infection and three measures of sociality in Asian elephants. Behav Ecol Sociobiol 2022;76(7):87.
            doi: 10.1007/s00265-022-03192-8pubmed: 35765658google scholar: lookup
          5. Boelow H, Krücken J, Thomas E, Mirams G, von Samson-Himmelstjerna G. Comparison of FECPAK(G2), a modified Mini-FLOTAC technique and combined sedimentation and flotation for the coproscopic examination of helminth eggs in horses. Parasit Vectors 2022 May 12;15(1):166.
            doi: 10.1186/s13071-022-05266-ypubmed: 35549990google scholar: lookup
          6. Grimm P, Laroche N, Julliand S, Sorci G. Inclusion of Sainfoin in the Diet Might Alter Strongyle Infection in Naturally Infected Horses. Animals (Basel) 2022 Apr 7;12(8).
            doi: 10.3390/ani12080955pubmed: 35454202google scholar: lookup
          7. Tombak KJ, Easterling LA, Martinez L, Seng MS, Wait LF, Rubenstein DI. Divergent water requirements partition exposure risk to parasites in wild equids. Ecol Evol 2022 Mar;12(3):e8693.
            doi: 10.1002/ece3.8693pubmed: 35342568google scholar: lookup
          8. Steuer AE, Anderson HP, Shepherd T, Clark M, Scare JA, Gravatte HS, Nielsen MK. Parasite dynamics in untreated horses through one calendar year. Parasit Vectors 2022 Feb 8;15(1):50.
            doi: 10.1186/s13071-022-05168-zpubmed: 35135605google scholar: lookup
          9. Sallé G, Canlet C, Cortet J, Koch C, Malsa J, Reigner F, Riou M, Perrot N, Blanchard A, Mach N. Integrative biology defines novel biomarkers of resistance to strongylid infection in horses. Sci Rep 2021 Jul 12;11(1):14278.
            doi: 10.1038/s41598-021-93468-2pubmed: 34253752google scholar: lookup
          10. Scala A, Tamponi C, Sanna G, Predieri G, Meloni L, Knoll S, Sedda G, Dessì G, Cappai MG, Varcasia A. Parascaris spp. eggs in horses of Italy: a large-scale epidemiological analysis of the egg excretion and conditioning factors. Parasit Vectors 2021 May 8;14(1):246.
            doi: 10.1186/s13071-021-04747-wpubmed: 33964977google scholar: lookup
          11. Slater R, Frau A, Hodgkinson J, Archer D, Probert C. A Comparison of the Colonic Microbiome and Volatile Organic Compound Metabolome of Anoplocephala perfoliata Infected and Non-Infected Horses: A Pilot Study. Animals (Basel) 2021 Mar 9;11(3).
            doi: 10.3390/ani11030755pubmed: 33803473google scholar: lookup
          12. Gliga DS, Petrova N, Linnell JDC, Salemgareyev AR, Zuther S, Walzer C, Kaczensky P. Dynamics of Gastro-Intestinal Strongyle Parasites in a Group of Translocated, Wild-Captured Asiatic Wild Asses in Kazakhstan. Front Vet Sci 2020;7:598371.
            doi: 10.3389/fvets.2020.598371pubmed: 33363236google scholar: lookup
          13. 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 Oct 12;13(1):509.
            doi: 10.1186/s13071-020-04396-5pubmed: 33046130google scholar: lookup
          14. Sauermann CW, Leathwick DM, Lieffering M, Nielsen MK. Climate change is likely to increase the development rate of anthelmintic resistance in equine cyathostomins in New Zealand. Int J Parasitol Drugs Drug Resist 2020 Dec;14:73-79.
            doi: 10.1016/j.ijpddr.2020.09.001pubmed: 32992276google scholar: lookup
          15. Tombak KJ, Budischak SA, Hauck S, Martinez LA, Rubenstein DI. The non-invasive measurement of faecal immunoglobulin in African equids. Int J Parasitol Parasites Wildl 2020 Aug;12:105-112.
            doi: 10.1016/j.ijppaw.2020.05.005pubmed: 32528845google scholar: lookup
          16. Hedberg-Alm Y, Penell J, Riihimäki M, Osterman-Lind E, Nielsen MK, Tydén E. Parasite Occurrence and Parasite Management in Swedish Horses Presenting with Gastrointestinal Disease-A Case-Control Study. Animals (Basel) 2020 Apr 7;10(4).
            doi: 10.3390/ani10040638pubmed: 32272754google scholar: lookup
          17. Jenkins E, Backwell AL, Bellaw J, 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 Apr;11:183-190.
            doi: 10.1016/j.ijppaw.2020.02.002pubmed: 32095427google scholar: lookup
          18. Scare JA, Leathwick DM, Sauermann CW, Lyons ET, Steuer AE, Jones BA, Clark M, Nielsen MK. Dealing with double trouble: Combination deworming against double-drug resistant cyathostomins. Int J Parasitol Drugs Drug Resist 2020 Apr;12:28-34.
            doi: 10.1016/j.ijpddr.2019.12.002pubmed: 31883485google scholar: lookup
          19. Cain JL, Foulk D, Jedrzejewski E, Stofanak H, Nielsen MK. The importance of anthelmintic efficacy monitoring: results of an outreach effort. Parasitol Res 2019 Oct;118(10):2877-2883.
            doi: 10.1007/s00436-019-06423-6pubmed: 31422463google scholar: lookup
          20. Saeed MA, Beveridge I, Abbas G, Beasley A, Bauquier J, Wilkes E, Jacobson C, Hughes KJ, El-Hage C, O'Handley R, Hurley J, Cudmore L, Carrigan P, Walter L, Tennent-Brown B, Nielsen MK, Jabbar A. Systematic review of gastrointestinal nematodes of horses from Australia. Parasit Vectors 2019 Apr 29;12(1):188.
            doi: 10.1186/s13071-019-3445-4pubmed: 31036059google scholar: lookup
          21. 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 'nemabiome'. J Equine Sci 2019 Mar;30(1):1-5.
            doi: 10.1294/jes.30.1pubmed: 30944540google scholar: lookup
          22. 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 Apr;8:156-163.
            doi: 10.1016/j.ijppaw.2019.01.008pubmed: 30815358google scholar: lookup
          23. Byrne RL, Fogarty U, Mooney A, Marples NM, Holland CV. A comparison of helminth infections as assessed through coprological analysis and adult worm burdens in a wild host. Int J Parasitol Parasites Wildl 2018 Dec;7(3):439-444.
            doi: 10.1016/j.ijppaw.2018.11.003pubmed: 30533382google scholar: lookup
          24. Crotch-Harvey L, Thomas LA, Worgan HJ, Douglas JL, Gilby DE, McEwan NR. The effect of administration of fenbendazole on the microbial hindgut population of the horse. J Equine Sci 2018;29(2):47-51.
            doi: 10.1294/jes.29.47pubmed: 29991923google scholar: lookup
          25. Misuno E, Clark CR, Anderson SL, Jenkins E, Wagner B, Dembek K, Petrie L. Characteristics of parasitic egg shedding over a 1-year period in foals and their dams in 2 farms in central Saskatchewan. Can Vet J 2018 Mar;59(3):284-292.
            pubmed: 29599559
          26. Peachey LE, Molena RA, Jenkins TP, Di Cesare A, Traversa D, Hodgkinson JE, Cantacessi C. The relationships between faecal egg counts and gut microbial composition in UK Thoroughbreds infected by cyathostomins. Int J Parasitol 2018 May;48(6):403-412.
            doi: 10.1016/j.ijpara.2017.11.003pubmed: 29432771google scholar: lookup
          27. Seyoum Z, Zewdu A, Dagnachew S, Bogale B. Anthelmintic Resistance of Strongyle Nematodes to Ivermectin and Fenbendazole on Cart Horses in Gondar, Northwest Ethiopia. Biomed Res Int 2017;2017:5163968.
            doi: 10.1155/2017/5163968pubmed: 28265572google scholar: lookup
          28. Kaspar A, Pfister K, Nielsen MK, Silaghi C, Fink H, Scheuerle MC. Detection of Strongylus vulgaris in equine faecal samples by real-time PCR and larval culture - method comparison and occurrence assessment. BMC Vet Res 2017 Jan 11;13(1):19.
            doi: 10.1186/s12917-016-0918-ypubmed: 28077153google scholar: lookup
          29. Janssen IJ, Krücken J, Demeler J, Basiaga M, Kornaś S, von Samson-Himmelstjerna G. Genetic variants and increased expression of Parascaris equorum P-glycoprotein-11 in populations with decreased ivermectin susceptibility. PLoS One 2013;8(4):e61635.
            doi: 10.1371/journal.pone.0061635pubmed: 23637871google scholar: lookup
          30. Andersen UV, Howe DK, Dangoudoubiyam S, Toft N, Reinemeyer CR, Lyons ET, Olsen SN, Monrad J, Nejsum P, Nielsen MK. SvSXP: a Strongylus vulgaris antigen with potential for prepatent diagnosis. Parasit Vectors 2013 Apr 4;6:84.
            doi: 10.1186/1756-3305-6-84pubmed: 23557195google scholar: lookup
          31. Zhang W, Yie S, Yue B, Zhou J, An R, Yang J, Chen W, Wang C, Zhang L, Shen F, Yang G, Hou R, Zhang Z. Determination of Baylisascaris schroederi infection in wild giant pandas by an accurate and sensitive PCR/CE-SSCP method. PLoS One 2012;7(7):e41995.
            doi: 10.1371/journal.pone.0041995pubmed: 22911871google scholar: lookup
          32. 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 Dec;111(6):2265-71.
            doi: 10.1007/s00436-012-3077-5pubmed: 22903448google scholar: lookup
          33. Khosravi M, Kavosh F, Taghavi-Moghadam A, Ghaem-Maghami S, Pirali-Kheirabadi K, Rahimi-Feyli P, Navid-Pour S, Amin-Pour A, Arbabi F. Comparison of helminth and hard tick infestation between riding and work horses in Ahwaz, Iran. Comp Clin Path 2012 Jun;21(3):333-336.
            doi: 10.1007/s00580-011-1280-xpubmed: 22707930google scholar: lookup
          34. Lyons ET, Tolliver SC, Kuzmina TA. Investigation of strongyle EPG values in horse mares relative to known age, number positive, and level of egg shedding in field studies on 26 farms in Central Kentucky (2010-2011). Parasitol Res 2012 Jun;110(6):2237-45.
            doi: 10.1007/s00436-011-2755-zpubmed: 22167377google scholar: lookup
          35. Mohtasebi S, Ahn S, Karimi M, Saberi M, Gilleard JS, Poissant J. Enhanced detection of equine strongyles: Insights from morphological and nemabiome metabarcoding approaches in northern Iran. Equine Vet J 2026 Mar;58(2):508-522.
            doi: 10.1111/evj.70120pubmed: 41316832google scholar: lookup
          36. Wang T, Chen X, Yan X, Su Y, Gao W, Liu C, Wang W. Progress in serology and molecular biology of equine parasite diagnosis: sustainable control strategies. Front Vet Sci 2025;12:1663577.
            doi: 10.3389/fvets.2025.1663577pubmed: 40979365google scholar: lookup
          37. Ochigbo GO, Ahn S, Belhumeur KA, Poissant J, Rosa BV. 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 2025 Aug;27:101091.
            doi: 10.1016/j.ijppaw.2025.101091pubmed: 40524829google scholar: lookup
          38. Nielsen MK, Pyatt A, Perrett J, Tydén E, van Doorn D, Pihl TH, Schmidt JS, von Samson-Himmelstjerna G, Beasley A, Abbas G, Jabbar A. Global equine parasite control guidelines: Consensus or confusion?. Int J Parasitol Drugs Drug Resist 2025 Aug;28:100600.
            doi: 10.1016/j.ijpddr.2025.100600pubmed: 40472642google scholar: lookup
          39. Whitlock F, van Dijk J, Hodgkinson JE, Grewar JD, Newton JR. Reasons to be fearful? Rising proportions of positive faecal worm egg counts among UK horses (2007-2023). Equine Vet J 2025 Nov;57(6):1572-1583.
            doi: 10.1111/evj.14478pubmed: 39840839google scholar: lookup
          40. 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 Dec 17;123(12):410.
            doi: 10.1007/s00436-024-08438-0pubmed: 39688721google scholar: lookup
          41. Kuzmina TA, Königová A, Antipov A, Kuzmin Y, Kharchenko V, Syrota Y. Changes in equine strongylid communities after two decades of annual anthelmintic treatments at the farm level. Parasitol Res 2024 Nov 25;123(11):394.
            doi: 10.1007/s00436-024-08417-5pubmed: 39585485google scholar: lookup
          42. Hedberg Alm Y, Tydén E, Martin F, Lernå J, Halvarsson P. Farm size and biosecurity measures associated with Strongylus vulgaris infection in horses. Equine Vet J 2025 May;57(3):703-711.
            doi: 10.1111/evj.14212pubmed: 39171858google scholar: lookup
          43. Kuzmina TA, Königová A, Burcáková L, Babjak M, Syrota Y. Strongylids of Domestic Horses in Eastern Slovakia: Species Diversity and Evaluation of Particular Factors Affecting Strongylid Communities. Acta Parasitol 2024 Jun;69(2):1284-1294.
            doi: 10.1007/s11686-024-00854-7pubmed: 38775915google scholar: lookup
          44. Matthews JB, Peczak N, Lightbody KL. The Use of Innovative Diagnostics to Inform Sustainable Control of Equine Helminth Infections. Pathogens 2023 Oct 11;12(10).
            doi: 10.3390/pathogens12101233pubmed: 37887749google scholar: lookup
          45. Buono F, Veneziano V, Veronesi F, Molento MB. Horse and donkey parasitology: differences and analogies for a correct diagnostic and management of major helminth infections. Parasitology 2023 Oct;150(12):1119-1138.
            doi: 10.1017/S0031182023000525pubmed: 37221816google scholar: lookup
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