Prevalence and diversity of ascarid and strongylid nematodes in Australian Thoroughbred horses using next-generation sequencing and bioinformatic tools.
Abstract: The study presents the results of a cross-sectional survey to describe the epidemiology of ascarid and strongylid nematodes in horses, the impact of diverse climatic conditions on parasite diversity and the levels of faecal egg shedding in different age groups of managed Thoroughbred horses. Individual faecal samples (n = 1377) collected from 62 Thoroughbred farms across four climatic zones in Australia were analysed using the modified McMaster technique for faecal egg counts (FECs) and strongylid nematodes were identified utilising PCR-directed next-generation sequencing (NGS) of the second internal transcribed spacer of the nuclear ribosomal DNA (ITS-2). Across all age groups, the prevalence of ascarid and strongylid nematodes was 12% (95% confidence interval 10-14%) and 72% (70-74%), respectively. Based on strongylid FECs, yearlings had the highest prevalence (89%) followed by weanlings (83%), foals (79%), wet mares (61%), dry mares (59%) and stallions (54%). However, for Parascaris spp., foals had the highest prevalence (46%) followed by weanlings (32%) and yearlings (13%). The highest mean FECs for Parascaris spp. were observed in foals (418 eggs per gram [EPG] of faeces) while those for strongylids were in yearlings (1002 EPG). Of the adult horses (mares and stallions), 67% (489 of 729) and 11% (77 of 729) were low (i.e., ≤250 EPG) and moderate (i.e., 251-500 EPG) strongylid egg-shedders, respectively. Strongylid egg shedding varied across climatic zones, with the highest mean FECs in the summer rainfall (723 EPG) followed by non-seasonal rainfall (629 EPG), winter rainfall (613 EPG), and Mediterranean (606 EPG) rainfall zones. Twenty-three nematode species were detected using NGS, with Cylicostephanus longibursatus (28%), Cylicocyclus nassatus (23%) and Coronocyclus coronatus (23%), being the most abundant species. Three species of Strongylus (i.e., S. vulgaris, S. equinus and S. edentatus) were also detected. The nemabiome composition, species richness and relative abundance varied within horse age and between climatic zones. These empirical findings provide a comprehensive understanding of the prevalence of parasites within horse populations and the multifaceted factors that influence their occurrence, thereby allowing for the formulation of tailored strategies aimed at parasite control in domestic horses.
Copyright © 2023 The Authors. Published by Elsevier B.V. All rights reserved.
Publication Date: 2023-10-14 PubMed ID: 37844388DOI: 10.1016/j.vetpar.2023.110048Google Scholar: Lookup
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Summary
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The research focuses on assessing the prevalence and diversity of ascarid (roundworm) and strongylid (intestinal worm) parasites in Australian Thoroughbred horses. The diet, climatic conditions, and age of the horses were among the factors considered in the study.
Research Approach and Methodology
- The research was based on a cross-sectional survey in which the epidemiology of ascarid and strongylid nematodes in horses was examined.
- A total of 1377 faecal samples were collected from 62 Thoroughbred farms, located across four climatic zones in Australia.
- The modified McMaster technique was used for faecal egg counts (FECs), a common method for estimating parasitic worm burden in animals.
- Next-generation sequencing (NGS) was used for identifying the strongylid nematodes at the genetic level. The researchers utilized PCR (Polymerase Chain Reaction)-directed NGS on the second internal transcribed spacer of the nuclear ribosomal DNA (ITS-2). This DNA segment is commonly used to identify and categorize different species of nematodes.
Key Findings
- The study found prevalence rates of 12% for ascarid parasites and 72% for strongylid parasites among all age groups of horses.
- Yearlings (one-to-two-year-olds) had the highest prevalence of strongylid infection (89%) while the foals (up to one year) had the highest prevalence of Ascarid infection (46%).
- Faecal egg counts found the highest mean egg count for Parascaris spp. (a genus of ascarid) in foals (418 eggs per gram (EPG) of faeces), and strongylids in yearlings (1002 EPG).
- Strongylid egg shedding varied across climatic zones, showing the highest egg count in areas with summer rainfall, followed by non-seasonal, winter and Mediterranean rainfall zones.
- The NGS analysis revealed the presence of 23 species of nematodes, with Cylicostephanus longibursatus, Cylicocyclus nassatus and Coronocyclus coronatus being the most common.
Implications of the Findings
- The findings provide significant insight into the prevalence of nematode parasites in different categories of horses and the multifaceted factors that influence their occurrence.
- This comprehensive understanding can guide the creation of effective, tailored strategies for controlling parasites in domestic horses.
Cite This Article
APA
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.
(2023).
Prevalence and diversity of ascarid and strongylid nematodes in Australian Thoroughbred horses using next-generation sequencing and bioinformatic tools.
Vet Parasitol, 323, 110048.
https://doi.org/10.1016/j.vetpar.2023.110048 Publication
Researcher Affiliations
- Melbourne Veterinary School, The University of Melbourne, Werribee, Victoria 3030, Australia.
- Melbourne Veterinary School, The University of Melbourne, Werribee, Victoria 3030, Australia.
- Melbourne Veterinary School, The University of Melbourne, Werribee, Victoria 3030, Australia.
- School of Agriculture and Food Sustainability, University of Queensland, Gatton, Queensland 4343, Australia.
- Melbourne Veterinary School, The University of Melbourne, Werribee, Victoria 3030, Australia.
- Melbourne Veterinary School, The University of Melbourne, Werribee, Victoria 3030, Australia.
- Melbourne Veterinary School, The University of Melbourne, Werribee, Victoria 3030, Australia.
- Racing Victoria, Flemington, Victoria 3031, Australia.
- Centre for Animal Production and Health, Murdoch University, Murdoch, Western Australia 6150, Australia.
- Scone Equine Hospital, Scone, New South Wales 2337, Australia.
- Scone Equine Hospital, Scone, New South Wales 2337, Australia.
- Swettenham Stud, Nagambie, Victoria 3608, Australia.
- Melbourne Veterinary School, The University of Melbourne, Werribee, Victoria 3030, Australia.
- M.H. Gluck Equine Research Center, Department of Veterinary Science, University of Kentucky, Lexington, KY, USA.
- Melbourne Veterinary School, The University of Melbourne, Werribee, Victoria 3030, Australia.
- Centre for Animal Production and Health, Murdoch University, Murdoch, Western Australia 6150, Australia.
- School of Agricultural, Environmental and Veterinary Sciences, Charles Sturt University, Wagga Wagga, New South Wales, Australia.
- Melbourne Veterinary School, The University of Melbourne, Werribee, Victoria 3030, Australia. Electronic address: jabbara@unimelb.edu.au.
MeSH Terms
- Animals
- Horses
- Horse Diseases / parasitology
- Horse Diseases / epidemiology
- Prevalence
- Australia / epidemiology
- Feces / parasitology
- High-Throughput Nucleotide Sequencing / veterinary
- Cross-Sectional Studies
- Female
- Male
- Computational Biology
- Parasite Egg Count / veterinary
- Strongylida Infections / veterinary
- Strongylida Infections / epidemiology
- Strongylida Infections / parasitology
- Ascaridoidea / genetics
- Ascaridoidea / isolation & purification
Conflict of Interest Statement
Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work stated in this report.
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