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Animals : an open access journal from MDPI2024; 14(4); 574; doi: 10.3390/ani14040574

Patterns of Equine Small Strongyle Species Infection after Ivermectin Intervention in Thailand: Egg Reappearance Period and Nemabiome Metabarcoding Approach.

Abstract: The indiscriminate use of anthelmintics to control parasitic nematodes in horses has led to the emergence of anthelmintic resistance worldwide. However, there are no data available on using ivermectin for treating strongyle infections within domesticated horses in Thailand. Therefore, this study aimed to use the fecal egg count reduction (FECR) test to determine the strongylid egg reappearance period (ERP). Additionally, the nemabiome metabarcoding approach is incorporated to study patterns of strongyle species infection following ivermectin treatment. The study results indicate that, although ivermectin effectively eliminated adult strongyle parasites within two weeks post-treatment, the ERP was shortened to 6 weeks post-treatment with a mean FECR of 70.4% (95% CI 46.1-84.0). This potentially indicates a recent change in drug performance. In addition, nemabiome metabarcoding revealed that strongyle species have different levels of susceptibility in response to anthelmintic drugs. The reduction in ERP was associated with the early reappearance of specific species, dominated by and , indicating the lower susceptibility of these species. In contrast, , , and were not found post-treatment, indicating the high level of susceptibility of these species. This information is vital for comprehending the factors contributing to the emergence of resistance and for devising strategies to manage and control strongyle infections in horses.
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Publication Date: 2024-02-08 PubMed ID: 38396542PubMed Central: PMC10886017DOI: 10.3390/ani14040574Google 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.

Research Overview

  • This study investigated the effectiveness of ivermectin in treating small strongyle parasite infections in horses in Thailand.
  • It focused on identifying how quickly parasite eggs reappear after treatment and which species show resistance using genetic sequencing methods.

Background and Purpose

  • Parasitic nematodes, especially strongyles, commonly infect horses and are controlled using anthelmintics like ivermectin.
  • Indiscriminate or repeated use of these drugs has led to anthelmintic resistance globally, reducing treatment effectiveness.
  • Prior to this study, there was no data on ivermectin’s effectiveness against strongyles in domestic horses in Thailand.
  • The research aimed to:
    • Determine the Egg Reappearance Period (ERP), which is the time after treatment when parasite eggs start to reappear in feces, indicating possible drug resistance.
    • Use a nemabiome metabarcoding approach, a genetic sequencing method that identifies parasite species in fecal samples, to study species-specific responses to ivermectin.

Methods Used

  • Fecal egg count reduction (FECR) tests measured the reduction in parasite egg numbers following ivermectin treatment in infected horses.
  • Monitoring was done at multiple time points post-treatment to determine when parasite eggs started to reappear, defining the ERP.
  • The nemabiome metabarcoding approach involved DNA sequencing of parasite eggs from fecal samples to identify which strongyle species were present before and after treatment.

Key Findings

  • Ivermectin effectively eliminated adult strongyle parasites within 2 weeks post-treatment.
  • The ERP was shortened to just 6 weeks after treatment, with a mean fecal egg count reduction of 70.4%, suggesting reduced drug efficacy compared to expected longer ERPs.
  • This shortened ERP implies a potential emergence of ivermectin resistance or decreased drug performance in this horse population.
  • Species-specific analysis showed that:
    • Some strongyle species reappeared early post-treatment, indicating lower susceptibility or emerging resistance to ivermectin.
    • Other species were absent entirely after treatment, suggesting they remain highly susceptible to the drug.
  • Specific species names were not fully provided in the abstract, but the distinction between resistant species and susceptible species helps identify targets for future control strategies.

Implications of the Study

  • The findings highlight the importance of monitoring both overall parasite burden and species-specific resistance patterns when using anthelmintics.
  • Shortened ERP can serve as an early warning sign for the development of resistance, requiring adjustments in worm control protocols.
  • Knowledge about which species show resistance can assist in targeted management approaches, potentially incorporating alternative drugs or integrated parasite control methods.
  • The use of nemabiome metabarcoding provides a powerful tool for precise species identification and surveillance, supporting effective veterinary parasitology practices.
  • Ultimately, these results can inform veterinarians and horse owners in Thailand and similar settings on optimizing treatment schedules and preventing further resistance development.

Cite This Article

APA
Hamad MH, Islam SI, Jitsamai W, Chinkangsadarn T, Naraporn D, Ouisuwan S, Taweethavonsawat P. (2024). Patterns of Equine Small Strongyle Species Infection after Ivermectin Intervention in Thailand: Egg Reappearance Period and Nemabiome Metabarcoding Approach. Animals (Basel), 14(4), 574. https://doi.org/10.3390/ani14040574

Publication

Animals : an open access journal from MDPI
ISSN: 2076-2615
NlmUniqueID: 101635614
Country: Switzerland
Language: English
Volume: 14
Issue: 4
PII: 574

Researcher Affiliations

Hamad, Mohamed H
  • The International Graduate Program of Veterinary Science and Technology (VST), Faculty of Veterinary Science, Chulalongkorn University, Bangkok 10330, Thailand.
  • Department of Animal Infectious Diseases, Faculty of Veterinary Medicine, Zagazig University, Zagazig 44511, Egypt.
  • Parasitology Unit, Department of Veterinary Pathology, Faculty of Veterinary Science, Chulalongkorn University, Bangkok 10330, Thailand.
Islam, Sk Injamamul
  • The International Graduate Program of Veterinary Science and Technology (VST), Faculty of Veterinary Science, Chulalongkorn University, Bangkok 10330, Thailand.
  • Parasitology Unit, Department of Veterinary Pathology, Faculty of Veterinary Science, Chulalongkorn University, Bangkok 10330, Thailand.
Jitsamai, Wanarit
  • Department of Parasitology and Entomology, Faculty of Public Health, Mahidol University, Bangkok 10400, Thailand.
Chinkangsadarn, Teerapol
  • Department of Surgery, Faculty of Veterinary Science, Chulalongkorn University, Bangkok 10330, Thailand.
Naraporn, Darm
  • Horse Farm and Laboratory Animal Breeding Center, Queen Saovabha Memorial Institute, The Thai Red Cross Society, Hua-Hin 77110, Thailand.
Ouisuwan, Suraseha
  • Horse Farm and Laboratory Animal Breeding Center, Queen Saovabha Memorial Institute, The Thai Red Cross Society, Hua-Hin 77110, Thailand.
Taweethavonsawat, Piyanan
  • Parasitology Unit, Department of Veterinary Pathology, Faculty of Veterinary Science, Chulalongkorn University, Bangkok 10330, Thailand.
  • Biomarkers in Animals Parasitology Research Unit, Chulalongkorn University, Bangkok 10330, Thailand.

Grant Funding

  • FOODF67310022 / Thailand Science Research and Innovation Fund

Conflict of Interest Statement

The authors declare no conflict of interest.

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Citations

This article has been cited 3 times.
  1. 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.
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