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Elghryani N, Lawlor A, McOwan T, de Waal T. Unravelling the Effectiveness of Anthelmintic Treatments on Equine Strongyles on Irish Farms. Animals (Basel) 2024; 14:1958. [PMID: 38998069 PMCID: PMC11240484 DOI: 10.3390/ani14131958] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2024] [Revised: 06/19/2024] [Accepted: 06/26/2024] [Indexed: 07/14/2024] Open
Abstract
Over the preceding decades, the widespread dependence on anthelmintic drugs for managing nematodes in grazing equids has given rise to resistance against commonly used anthelmintics in various countries. This study explores the prevalence of anthelmintic resistance across 44 horse farms in Ireland. Anthelmintic efficacy was evaluated through fecal egg count reduction (FECR) tests employing the mini-FLOTAC technique. Resistance to benzimidazoles was identified in 12 out of 14 farms (FECR range: 0.00% to 86.2%). Ivermectin resistance was observed on two farms, one with an FECR of 80.70% and another with an FECR of 96.10% (lower 95% high probability density interval (HPD) <90%, 11.70%). On the remaining six farms, the reduction with ivermectin still exceeded 95%. The reduced efficacy of moxidectin was noted on two farms (FECR = 86.90% and 93.50%) and on a third farm with an FECR of 99.50 and a lower HPD interval < 90% at 24.00%. In summary, these findings emphasize the urgent need for alternative strategies in equine strongyle control that reduce reliance on anthelmintics and prioritize effective management practices on Irish equine farms to hinder the impending development of drug-resistant parasite populations.
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Affiliation(s)
- Nagwa Elghryani
- School of Veterinary Medicine, University College Dublin, D04 W6F6 Dublin, Ireland
- Telenostic Limited, R95 WN20 Kilkenny, Ireland
- Department of Biology, Faculty of Arts and Sciences-Gamines, University of Benghazi, Benghazi 1308, Libya
| | - Amanda Lawlor
- School of Veterinary Medicine, University College Dublin, D04 W6F6 Dublin, Ireland
| | | | - Theo de Waal
- School of Veterinary Medicine, University College Dublin, D04 W6F6 Dublin, Ireland
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Horner A, Bamford NJ, Stear MJ, Piedrafita D, Jabbar A, Hughes KJ, El-Hage CM, Preston S. Strongyle egg shedding and egg reappearance periods in horses with pituitary pars intermedia dysfunction. Vet Parasitol 2024; 328:110176. [PMID: 38603926 DOI: 10.1016/j.vetpar.2024.110176] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2023] [Revised: 03/26/2024] [Accepted: 03/26/2024] [Indexed: 04/13/2024]
Abstract
Pituitary pars intermedia dysfunction (PPID) is the most common endocrine disorder of older horses. Immune dysfunction in horses with PPID could increase susceptibility to infectious diseases, including strongyle infections; however, few data are available. The aim of this study was to determine if horses with PPID had increased strongyle faecal egg counts (FEC) compared with control horses, over a fourteen-week period in Victoria, Australia. Clinical signs and plasma adrenocorticotropic hormone (ACTH) concentrations were used to categorise horses into PPID (n=14) or control (n=31) groups. Faecal samples were collected for FEC determination prior to anthelmintic treatment, and fortnightly post-treatment for each horse. Generalised linear mixed modelling, using a gamma distribution, was used to compare differences between groups in the repeated measures study. The confounding variable of age was controlled for as a fixed effect. Following anthelmintic treatment, mean FEC was greater for the PPID group compared to the control group on day 56 (405 ± 756 eggs per gram [EPG] vs 40 ± 85 EPG, p=0.05) and day 70 (753 ±1598 EPG vs 82 ±141 EPG, p=0.04). There were no differences in mean FEC between groups on days 84 and 98. Cumulative FEC (day 14 to day 98) was significantly greater for the PPID horses than control horses (2118 ± 4016 EPG vs 798 ± 768 EPG, p<0.0001). Group egg reappearance period was shorter for PPID horses (day 56 post-anthelmintic treatment) compared to control horses (day 70) and 30% of the PPID horses reached a FEC threshold of >200 EPG on day 42, compared to 0% of control horses (p=0.02). These results suggest that the rate of a re-established patent infection between groups could be different due to a comprised immune response in PPID horses or differences in the host-parasite relationship regarding encysted stage larvae. However, despite differences between groups, some horses with PPID consistently had no detectable or low FEC (<200 EPG) during the study period. These findings highlight the importance of individual FEC monitoring to determine if anthelmintic treatment is required, in line with sustainable parasite management practices.
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Affiliation(s)
- Adelaina Horner
- Institute of Innovation, Science and Sustainability, Federation University, Victoria 3350, Australia
| | - Nicholas J Bamford
- Melbourne Veterinary School, The University of Melbourne, Parkville, Victoria 3010, Australia
| | - Michael J Stear
- School of Life Sciences, La Trobe University, Melbourne, Victoria 3086, Australia
| | - David Piedrafita
- Institute of Innovation, Science and Sustainability, Federation University, Victoria 3350, Australia
| | - Abdul Jabbar
- Melbourne Veterinary School, The University of Melbourne, Parkville, Victoria 3010, Australia
| | - Kristopher J Hughes
- School of Agricultural, Environmental and Veterinary Sciences, Charles Sturt University, Wagga Wagga, NSW 2678, Australia
| | - Charles M El-Hage
- Melbourne Veterinary School, The University of Melbourne, Parkville, Victoria 3010, Australia.
| | - Sarah Preston
- Institute of Innovation, Science and Sustainability, Federation University, Victoria 3350, Australia.
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Nielsen MK, Finnerty CA, Ripley NE, Page AE, McClendon ME, Adams AA. Ivermectin performance in horses diagnosed with equine endocrine disorders. Vet Parasitol 2024; 328:110182. [PMID: 38603925 DOI: 10.1016/j.vetpar.2024.110182] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2024] [Revised: 04/03/2024] [Accepted: 04/04/2024] [Indexed: 04/13/2024]
Abstract
Anthelmintic performance against equine cyathostomins can be evaluated by two different non-terminal measures; the Fecal Egg Count Reduction Test (FECRT) and the Egg Reappearance Period (ERP). Most available FECRT and ERP data have been determined in populations of young horses, and very little information is available from mature and senior horses. Furthermore, it is unknown how commonly occurring equine endocrine disorders such as Insulin dysregulation (ID) and Pituitary pars intermedia dysfunction (PPID) may interfere with these measurements, but it has been suggested that horses with these conditions could be more susceptible to parasitic infections. A research population of senior horses and horses with or without PPID, ID, or both were enrolled in this study. All strongylid egg count positive horses were included in an ivermectin (200 μg/kg) efficacy study. These were distributed among the following groups: ID: six, PPID: three, PPID and ID: seven, and healthy controls: three. Strongylid fecal egg counts were determined on the day of ivermectin administration, at two weeks post deworming, and on weekly intervals until eight weeks post treatment. Determination of FECRT and ERP were carried out following World Association for the Advancement of Veterinary Parasitology guidelines. Results revealed high ivermectin efficacy with mean egg count reduction at 99.7% or above in all groups at two weeks post treatment. Egg reappearance was documented at six and seven weeks in the ID and PPID/ID groups, respectively, whereas the PPID and healthy control groups both had ERP at 8 weeks. Statistical analysis found no significant differences in egg count levels between groups during the study. The expected ERP for ivermectin is 8-10 weeks, meaning that two of the groups displayed shortened ERPs. However, due to the small group sizes, these data should be interpreted with caution. Nonetheless, results do indicate a need for further investigation of the possible influence of endocrine disorders on anthelmintic performance in horses.
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Affiliation(s)
- M K Nielsen
- Maxwell H. Gluck Equine Research Center, Department of Veterinary Science, University of Kentucky, 1400 Nicholasville Rd, Lexington, KY 40503, USA.
| | - C A Finnerty
- Maxwell H. Gluck Equine Research Center, Department of Veterinary Science, University of Kentucky, 1400 Nicholasville Rd, Lexington, KY 40503, USA
| | - N E Ripley
- Maxwell H. Gluck Equine Research Center, Department of Veterinary Science, University of Kentucky, 1400 Nicholasville Rd, Lexington, KY 40503, USA
| | - A E Page
- Maxwell H. Gluck Equine Research Center, Department of Veterinary Science, University of Kentucky, 1400 Nicholasville Rd, Lexington, KY 40503, USA
| | - M E McClendon
- Maxwell H. Gluck Equine Research Center, Department of Veterinary Science, University of Kentucky, 1400 Nicholasville Rd, Lexington, KY 40503, USA
| | - A A Adams
- Maxwell H. Gluck Equine Research Center, Department of Veterinary Science, University of Kentucky, 1400 Nicholasville Rd, Lexington, KY 40503, USA
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Merlin A, Larcher N, Vallé-Casuso JC. The first report of triple anthelmintic resistance on a French Thoroughbred stud farm. Int J Parasitol Drugs Drug Resist 2024; 24:100528. [PMID: 38422764 PMCID: PMC10910056 DOI: 10.1016/j.ijpddr.2024.100528] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2023] [Revised: 02/19/2024] [Accepted: 02/19/2024] [Indexed: 03/02/2024]
Abstract
This study assessed the anthelmintic resistance in strongylid nematodes against commonly used anthelmintic (AH) drugs in a French galloping racehorse stud farm from March to December 2023. Faecal egg count reduction tests (FECRTs) were conducted in three different groups of Thoroughbred yearlings (a group of 6 males, a group of 13 females and a group of 8 females and 3 males) following the new World Association for the Advancement of Veterinary Parasitology (WAAVP) guidelines. The efficacy of fenbendazole was tested in two groups once during the monitoring period (in March), the efficacy of ivermectin in 3 groups twice (in March-April and in November-December) and the efficacy of pyrantel in one group once (in May-June). For each FECRT, the 90% confidence interval of the percentage faecal egg count reduction was calculated using the hybrid Frequentist/Bayesian analysis method. The resistance in strongylids was observed to fenbendazole, pyrantel and ivermectin in all the groups in which these drugs were tested. The number of animals in each group was sufficient to reach ≥80% power for the resistance test. The results highlight the first case of triple AH resistance in strongylids in France. Further studies involving more farms and equids are required to assess the prevalence of AH resistance in France and refine recommendations for owners.
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Affiliation(s)
- Aurélie Merlin
- Anses, Laboratory for Animal Health in Normandy, Physiopathology and Epidemiology of Equine Diseases Unit, 14430 Goustranville, France; Mixed Technological Unit "Equine Health and Welfare - Organisation and Traceability of the Equine Industry" (UMT SABOT), France.
| | - Nicolas Larcher
- Anses, Laboratory for Animal Health in Normandy, Physiopathology and Epidemiology of Equine Diseases Unit, 14430 Goustranville, France; Mixed Technological Unit "Equine Health and Welfare - Organisation and Traceability of the Equine Industry" (UMT SABOT), France
| | - José-Carlos Vallé-Casuso
- Anses, Laboratory for Animal Health in Normandy, Physiopathology and Epidemiology of Equine Diseases Unit, 14430 Goustranville, France; Mixed Technological Unit "Equine Health and Welfare - Organisation and Traceability of the Equine Industry" (UMT SABOT), France
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5
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Abbas G, Ghafar A, McConnell E, Beasley A, Bauquier J, Wilkes EJA, El-Hage C, Carrigan P, Cudmore L, Hurley J, Gauci CG, Beveridge I, Ling E, Jacobson C, Stevenson MA, Nielsen MK, Hughes KJ, Jabbar A. A national survey of anthelmintic resistance in ascarid and strongylid nematodes in Australian Thoroughbred horses. Int J Parasitol Drugs Drug Resist 2024; 24:100517. [PMID: 38064906 PMCID: PMC10757041 DOI: 10.1016/j.ijpddr.2023.11.006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2023] [Revised: 11/19/2023] [Accepted: 11/19/2023] [Indexed: 01/02/2024]
Abstract
This study quantified the extent of anthelmintic resistance (AR) in ascarid and strongylid nematodes against commonly used anthelmintics in Australian Thoroughbred horses. Faecal egg count reduction tests (FECRTs, n = 86) and egg reappearance period (ERP) tests were conducted on 22 farms across Australia. Faecal egg counts (FECs) were determined using the modified McMaster technique, and percent faecal egg count reduction (%FECR) was calculated using the Bayesian hierarchical model and hybrid Frequentist/Bayesian analysis method. The results were interpreted using old (published in 1992) and new (2023) research guidelines of the World Association for the Advancement of Veterinary Parasitology (WAAVP). The species composition of strongylid nematodes was detected utilising a DNA-metabarcoding method using pre- and post-treatment samples. Resistance was observed in strongylid nematodes to commonly used single-active and combination anthelmintics, including ivermectin (IVM %FECR range: 82%-92%; 95% lower credible interval (LCI) range: 80%-90%), abamectin (ABM: 73%-92%; 65%-88%), moxidectin (MOX: 89%-91%; 84%-89%), oxfendazole (OFZ: 0%-56%; 0%-31%) and its combination with pyrantel (OFZ + PYR: 0%-82%; 0%-78%). Resistance in Parascaris spp. was observed to IVM (10%-43%; 0%-36%), ABM (0%; 0%) and MOX (0%; 0%). When the new thresholds recommended by the WAAVP were used, AR was detected in six additional FECRTs for strongylids and three more tests for Parascaris spp., introducing resistance to OFZ and OFZ + PYR in the latter. Shortened ERPs (4-6 weeks) of strongylids were observed in 31 FECRTs in which AR was not detected at 2 weeks post-treatment for all the anthelmintics tested. Among cyathostomins, Cylicocyclus nassatus, Cylicostephanus longibursatus and Coronocyclus coronatus were the most prevalent species at 2 weeks post-treatment, whereas the main species appearing at five weeks following treatments with macrocyclic lactones were Cylicocyclus nassatus, Cylicostephanus longibursatus and Cylicocyclus ashworthi. After treatment with OFZ + PYR, the latter three, plus Coronocyclus coronatus and Cyathostomum catinatum, were detected at 5 weeks post-treatment. Overall, the study highlights the prevalence of AR in both ascarids and strongylid nematodes against commonly used anthelmintic products to control worms in Australian horses. The results indicate that ML combination products provided acceptable efficacy at 2 weeks. However, ERP calculations suggest that products work less effectively than previously measured. It is suggested to regularly monitor the efficacy of the anthelmintics and consider changing the worm control practices to better manage worms and AR in Australian horses.
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Affiliation(s)
- Ghazanfar Abbas
- Melbourne Veterinary School, The University of Melbourne, Werribee, Victoria 3030, Australia
| | - Abdul Ghafar
- Melbourne Veterinary School, The University of Melbourne, Werribee, Victoria 3030, Australia
| | - Emma McConnell
- Centre for Animal Production and Health, Murdoch University, Murdoch, Western Australia, Australia
| | - Anne Beasley
- School of Agriculture and Food Sustainability, University of Queensland, Gatton, Queensland 4343, Australia
| | - Jenni Bauquier
- Melbourne Veterinary School, The University of Melbourne, Werribee, Victoria 3030, Australia
| | | | - Charles El-Hage
- Melbourne Veterinary School, The University of Melbourne, Werribee, Victoria 3030, Australia
| | - Peter Carrigan
- Scone Equine Hospital, Scone, New South Wales 2337, Australia
| | - Lucy Cudmore
- Scone Equine Hospital, Scone, New South Wales 2337, Australia
| | - John Hurley
- Swettenham Stud, Nagambie, Victoria 3608, Australia
| | - Charles G Gauci
- Melbourne Veterinary School, The University of Melbourne, Werribee, Victoria 3030, Australia
| | - Ian Beveridge
- Melbourne Veterinary School, The University of Melbourne, Werribee, Victoria 3030, Australia
| | - Elysia Ling
- Melbourne Veterinary School, The University of Melbourne, Werribee, Victoria 3030, Australia
| | - Caroline Jacobson
- Centre for Animal Production and Health, Murdoch University, Murdoch, Western Australia, Australia
| | - Mark A Stevenson
- Melbourne Veterinary School, The University of Melbourne, Werribee, Victoria 3030, Australia
| | - Martin K Nielsen
- M.H. Gluck Equine Research Center, Department of Veterinary Science, University of Kentucky, Lexington, KY, USA
| | - Kristopher J Hughes
- School of Agricultural, Environmental and Veterinary Sciences, Charles Sturt University, Wagga Wagga, New South Wales 2650, Australia
| | - Abdul Jabbar
- Melbourne Veterinary School, The University of Melbourne, Werribee, Victoria 3030, Australia.
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Hamad MH, Islam SI, Jitsamai W, Chinkangsadarn T, Naraporn D, Ouisuwan S, Taweethavonsawat P. Patterns of Equine Small Strongyle Species Infection after Ivermectin Intervention in Thailand: Egg Reappearance Period and Nemabiome Metabarcoding Approach. Animals (Basel) 2024; 14:574. [PMID: 38396542 PMCID: PMC10886017 DOI: 10.3390/ani14040574] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2023] [Revised: 02/07/2024] [Accepted: 02/07/2024] [Indexed: 02/25/2024] Open
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 Cylicostephanus longibursatus and Cylicocyclus nassatus, indicating the lower susceptibility of these species. In contrast, Poteriostomum imparidentatum, Triodontophorus nipponicus, and Triodontophorus serratus 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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Affiliation(s)
- Mohamed H. Hamad
- The International Graduate Program of Veterinary Science and Technology (VST), Faculty of Veterinary Science, Chulalongkorn University, Bangkok 10330, Thailand; (M.H.H.); (S.I.I.)
- 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
| | - Sk Injamamul Islam
- The International Graduate Program of Veterinary Science and Technology (VST), Faculty of Veterinary Science, Chulalongkorn University, Bangkok 10330, Thailand; (M.H.H.); (S.I.I.)
- Parasitology Unit, Department of Veterinary Pathology, Faculty of Veterinary Science, Chulalongkorn University, Bangkok 10330, Thailand
| | - Wanarit Jitsamai
- Department of Parasitology and Entomology, Faculty of Public Health, Mahidol University, Bangkok 10400, Thailand;
| | - Teerapol Chinkangsadarn
- Department of Surgery, Faculty of Veterinary Science, Chulalongkorn University, Bangkok 10330, Thailand;
| | - Darm Naraporn
- Horse Farm and Laboratory Animal Breeding Center, Queen Saovabha Memorial Institute, The Thai Red Cross Society, Hua-Hin 77110, Thailand; (D.N.); (S.O.)
| | - Suraseha Ouisuwan
- Horse Farm and Laboratory Animal Breeding Center, Queen Saovabha Memorial Institute, The Thai Red Cross Society, Hua-Hin 77110, Thailand; (D.N.); (S.O.)
| | - Piyanan Taweethavonsawat
- 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
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Cai E, Wu R, Wu Y, Gao Y, Zhu Y, Li J. A systematic review and meta-analysis on the current status of anthelmintic resistance in equine nematodes: A global perspective. Mol Biochem Parasitol 2024; 257:111600. [PMID: 38030084 DOI: 10.1016/j.molbiopara.2023.111600] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2023] [Revised: 11/22/2023] [Accepted: 11/22/2023] [Indexed: 12/01/2023]
Abstract
BACKGROUND The intensive application of anthelmintics in equine has led to considerable resistance in cyathostomins and Parascaris equorum. It has been well documented that benzimidazole (BZ) and pyrantel resistance is widespread in cyathostomins and Parascaris equorum. Since no new classes of anthelmintic have been introduced in the last 40 years, it is critical to be aware of the current risk factors of anthelmintic application to avoid further resistance. OBJECTIVE To review the factors affecting the level of anthelmintics resistance in equine around the world, type of anthelmintics, mode of application, dosage, nematode species, and location of anthelmintics application were evaluated and summarized. DESIGN/PROCEDURE A systematic review and meta-analyses following the PRISMA Framework were conducted to identify, evaluate, and synthesize primary literature reporting the efficacy of anthelmintic drugs in equines. Information on the bibliographic data, anthelmintic drugs, animals, continents, parasite genera, type of anthelmintics, and dosage was collected. Nonparametric tests (Kruskal-Wallis and Mann-Whitney) were used in SPSS (v.27) to investigate the association between variables. Factors that have a significant impact on efficacy have been subjected to binary logistic regression. Six meta-analyses were conducted in Microsoft Excel (2021) to qualify current resistance issues of the three major anthelmintics classes. RESULTS The final database was composed of 60 articles published between 1994 and 2022 with a total of 11835 animals. Anthelmintic class as well as anthelmintic active principle selection did have a significant effect on resistance (P < 0.01), whilst no correlation of the type of anthelmintics, mode of application, and dosage with efficacy were found. Anthelmintics resistance in ascarid was significantly more severe than in strongyle (P < 0.01). Macrocyclic lactone (ML) class and the benzimidazole and probenzimidazole (BP) class have the lowest efficacy against ascarid and strongyle, respectively (67.83% and 69.85%). The effect of location (by continent) also had a significant influence on the resistance of the ML class (P < 0.01). The resistance of the BP class which is the most prevalently applied was demonstrated in all six continents. Binary logistic regression revealed that parasite genera and drug class independently influenced the presence of drug resistance. The forest plots included in this study did not show a significant difference over time. CONCLUSION Current evidence indicated that anthelmintics resistance of ML and BP class were common in ascarid and strongyle. A combination of anthelmintics may reduce anthelmintics resistance, but multi-drug resistance may be a concern. Customerised anthelmintics strategy could help reduce resistance.
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Affiliation(s)
- Enjia Cai
- Equine Clinical Diagnostic Center, College of Veterinary Medicine, China Agricultural University, Beijing 100193, China
| | - Rongzheng Wu
- Equine Clinical Diagnostic Center, College of Veterinary Medicine, China Agricultural University, Beijing 100193, China
| | - Yuhong Wu
- College of Veterinary Medicine, University of Minnesota, St. Paul, MN 55108, United States
| | - Yu Gao
- University of Veterinary Medicine Hannover Foundation, Hannover D-30559, Germany
| | - Yiping Zhu
- Equine Clinical Diagnostic Center, College of Veterinary Medicine, China Agricultural University, Beijing 100193, China.
| | - Jing Li
- Equine Clinical Diagnostic Center, College of Veterinary Medicine, China Agricultural University, Beijing 100193, China.
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Elghryani N, McAloon C, Mincher C, McOwan T, de Waal T. Comparison of the Automated OvaCyte Telenostic Faecal Analyser versus the McMaster and Mini-FLOTAC Techniques in the Estimation of Helminth Faecal Egg Counts in Equine. Animals (Basel) 2023; 13:3874. [PMID: 38136911 PMCID: PMC10740962 DOI: 10.3390/ani13243874] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2023] [Revised: 12/11/2023] [Accepted: 12/13/2023] [Indexed: 12/24/2023] Open
Abstract
Gastrointestinal helminth parasites continue to be a significant threat to the health of equine. OvaCyte Telenostic (OCT) (Telenostic Ltd., Kilkenny, Ireland) has developed an automated digital microscope utilising Artificial Intelligence to identify and count the clinically important helminth species in equine, bovine, and ovine host species. In this paper, the performance of the OCT analyser was evaluated for the detection and counting of equine helminth species parasites and its performance compared to the currently accepted benchmark methods of faecal egg counts being the McMaster and the Mini-FLOTAC techniques. A pairwise comparison of tests was assessed based on the correlation of egg counts and Cohen's kappa agreement statistics for dichotomized outcomes. Bayesian latent class analysis was used to estimate the sensitivity and specificity of all three techniques in the absence of a gold standard for four helminth parasites (strongyles, Anoplocephala spp., Parascaris spp. and Strongyloides westeri). Based on the analysis of 783 equine faecal samples, we found a high level (ρ ≥ 0.94) of correlation between each pairwise comparison of techniques for strongyle egg counts. Cohen's kappa agreement between techniques was high for strongyles and S. westeri, moderate for Parascaris spp., and low for Anoplocephala spp. All three techniques had a high sensitivity and specificity (>0.90) for strongyles. Across helminth parasites, the sensitivity of the OCT was the highest of the three techniques evaluated for strongyles (0.98 v 0.96 and 0.94), Anoplocephala spp. (0.86 v 0.44 and 0.46) and Parascaris spp. (0.96 v 0.83 and 0.96); but lowest for S. westeri (0.74 v 0.88 and 0.88), compared to McMaster and Mini-FLOTAC, respectively. In terms of specificity, OCT was the lowest in two species (Parascaris spp. 0.96, Anoplocephala spp. 0.95). In conclusion, OCT has a sensitivity and specificity statistically similar to both McMaster and Mini-FLOTAC, and had a higher correlation with Mini-FLOTAC. The OCT point of care faecal analyser offers improved workflow, test turn-around time and does not require trained laboratory personnel to operate or interpret the results.
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Affiliation(s)
- Nagwa Elghryani
- Telenostic Limited, R95 WN20 Kilkenny, Ireland; (C.M.); (T.M.)
- Department of Biology, Faculty ofSciences-Qumnis, University of Benghazi, Benghazi 1308, Libya
- School of Veterinary Medicine, University College Dublin, D04 D6F6 Dublin, Ireland; (C.M.); (T.d.W.)
| | - Conor McAloon
- School of Veterinary Medicine, University College Dublin, D04 D6F6 Dublin, Ireland; (C.M.); (T.d.W.)
| | - Craig Mincher
- Telenostic Limited, R95 WN20 Kilkenny, Ireland; (C.M.); (T.M.)
| | - Trish McOwan
- Telenostic Limited, R95 WN20 Kilkenny, Ireland; (C.M.); (T.M.)
| | - Theo de Waal
- School of Veterinary Medicine, University College Dublin, D04 D6F6 Dublin, Ireland; (C.M.); (T.d.W.)
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Burcáková L, Königová A, Kuzmina TA, Austin CJ, Matthews JB, Lightbody KL, Peczak NA, Syrota Y, Várady M. Equine tapeworm (Anoplocephala spp.) infection: evaluation of saliva- and serum-based antibody detection methods and risk factor analysis in Slovak horse populations. Parasitol Res 2023; 122:3037-3052. [PMID: 37803152 PMCID: PMC10667452 DOI: 10.1007/s00436-023-07994-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2023] [Accepted: 09/26/2023] [Indexed: 10/08/2023]
Abstract
A lack of accurate information on the prevalence and distribution of Anoplocephala spp. infections on horse farms has led to insufficient attention to tapeworm control and increasing horse anoplocephaloses in Europe. Our study aimed to examine the occurrence of Anoplocephala spp. infection using coprological, serum- and saliva-based antibody detection methods and to analyze the risk factors associated with tapeworm infection in domestic horses in Slovakia. Fecal, serum, and saliva samples were collected from 427 horses from 31 farms in Slovakia. Additionally, a questionnaire study was conducted to collect information on tapeworm distribution on horse farms and analyze risk factors associated with infection. Fecal samples were examined by the mini-FLOTAC and the double centrifugation/combined sedimentation-flotation techniques. Serum and saliva samples were analyzed by ELISA to determine antibody levels against Anoplocephala spp. The effects of variables associated with an individual horse were tested for the positive result of the saliva ELISA test on Anoplocephala spp. Cestode eggs were detected in 1.99% of fecal samples (farm prevalence 12.90%), with no differences between the two coprological methods. Serum-based tapeworm ELISA results revealed that 39.39% of horses tested positive (farm prevalence 83.87%); while saliva-based tapeworm ELISA results revealed 56.95% positive horses (farm prevalence 96.77%). Binary logistic regression analysis revealed four meaningful predictors that significantly impacted the likelihood of detecting tapeworm infection in horses: horse age, pasture size, anthelmintic treatment scheme, and access to pasture. The influences of other variables associated with an individual horse were not significantly associated with detecting tapeworm infection.
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Affiliation(s)
- Ludmila Burcáková
- Institute of Parasitology, Slovak Academy of Sciences, Hlinkova 3, Kosice, 04001, Slovakia
- University of Veterinary Medicine and Pharmacy in Kosice, Komenskeho 73, Kosice, 04181, Slovakia
| | - Alzbeta Königová
- Institute of Parasitology, Slovak Academy of Sciences, Hlinkova 3, Kosice, 04001, Slovakia
| | - Tetiana A Kuzmina
- Institute of Parasitology, Slovak Academy of Sciences, Hlinkova 3, Kosice, 04001, Slovakia.
- I. I. Schmalhausen Institute of Zoology NAS of Ukraine, Bogdan Khmelnytsky Street, 15, Kyiv, 01054, Ukraine.
| | - Corrine J Austin
- Austin Davis Biologics Ltd, Unit 1 Denfield Lodge, Lower Street, Great Addington, Northants, NN14 4BL, UK
| | - Jacqueline B Matthews
- Austin Davis Biologics Ltd, Unit 1 Denfield Lodge, Lower Street, Great Addington, Northants, NN14 4BL, UK
| | - Kirsty L Lightbody
- Austin Davis Biologics Ltd, Unit 1 Denfield Lodge, Lower Street, Great Addington, Northants, NN14 4BL, UK
| | - Natalia A Peczak
- Austin Davis Biologics Ltd, Unit 1 Denfield Lodge, Lower Street, Great Addington, Northants, NN14 4BL, UK
| | - Yaroslav Syrota
- Institute of Parasitology, Slovak Academy of Sciences, Hlinkova 3, Kosice, 04001, Slovakia
- I. I. Schmalhausen Institute of Zoology NAS of Ukraine, Bogdan Khmelnytsky Street, 15, Kyiv, 01054, Ukraine
- African Amphibian Conservation Research Group, Unit for Environmental Sciences and Management, North-West University, Potchefstroom, South Africa
| | - Marian Várady
- Institute of Parasitology, Slovak Academy of Sciences, Hlinkova 3, Kosice, 04001, Slovakia
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Alm YH, Osterman-Lind E, Martin F, Lindfors R, Roepstorff N, Hedenström U, Fredriksson I, Halvarsson P, Tydén E. Retained efficacy of ivermectin against cyathostomins in Swedish horse establishments practicing selective anthelmintic treatment. Vet Parasitol 2023; 322:110007. [PMID: 37639919 DOI: 10.1016/j.vetpar.2023.110007] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2023] [Revised: 08/08/2023] [Accepted: 08/10/2023] [Indexed: 08/31/2023]
Abstract
Cyathostominae are ubiquitous to grazing horses and regarded the most prevalent internal parasite in the horse. Unfortunately, decades of indiscriminate use of anthelmintic drugs have resulted in the development of resistance in cyathostomins to all currently available drug groups, the most recent being a documented lack of efficacy to the macrocyclic lactones (ML). In vivo determination of anthelmintic resistance in horses most often utilises the faecal egg count reduction test (FECRT). Further, a shortened egg reappearance period (ERP) can indicate a change in response to the applied treatment and suggest an upcoming reduction of efficacy. Although both true resistance as demonstrated by the FECRT and shorter ERPs after ML treatment have now been shown in cyathostomins worldwide, the efficacy of ML as regards to cyathostomins in Sweden is currently unknown. The aim of the present study was therefore to determine FECRTs and ERPs after ivermectin (IVM) treatment in Swedish horses. Sixteen equestrian establishments with a minimum of six horses excreting at least 150 eggs per gram faeces (EPG) at screening were selected. For each establishment, FECRTs and ERPs were determined by collecting faecal samples prior to and 14 days after IVM treatment (200 µg/kg), and thereafter at weekly intervals for a total of eight weeks. All participants responded to a questionnaire detailing pasture management methods and anthelmintic routines.Questionnaire results showed that the majority of establishments (69%) only treated horses with anthelmintic drugs if indicated by faecal diagnostics and all of the establishments had a mean FECRT exceeding 99.0% and ERPs ranging from six to over eight weeks. The ERP was shown to increase with age as young individuals were shown to excrete cyathostomin eggs earlier after treatment compared with older horses (R = 0.21, p = 0.015). Riding schools, stud farms and those declaring not to use separate summer and winter paddocks had significantly shorter ERPs (p <0.01).In conclusion, retained ERPs and no confirmed resistance to IVM were found in Swedish equine establishments practising selective anthelmintic treatment, and supports the use of selective deworming regimens as a means of reducing the risk of anthelmintic resistance development.
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Affiliation(s)
- Ylva Hedberg Alm
- Department of Biomedical Science and Veterinary Public Health, Parasitology Unit, Swedish University of Agricultural Sciences, SE-750 07 Uppsala, Sweden.
| | - Eva Osterman-Lind
- Department of Microbiology, Section for Parasitology, National Veterinary Institute (SVA), SE-751 89 Uppsala, Sweden
| | - Frida Martin
- Department of Biomedical Science and Veterinary Public Health, Parasitology Unit, Swedish University of Agricultural Sciences, SE-750 07 Uppsala, Sweden
| | - Rebecca Lindfors
- Ambulatory Clinic, University Animal Hospital, Swedish University of Agricultural Sciences, SE-750 07 Uppsala, Sweden
| | - Nina Roepstorff
- Ridskolan Strömsholm AB, Stallbacken 6, Knytpunkten, SE-734 94 Strömsholm, Sweden
| | | | | | - Peter Halvarsson
- Department of Biomedical Science and Veterinary Public Health, Parasitology Unit, Swedish University of Agricultural Sciences, SE-750 07 Uppsala, Sweden
| | - Eva Tydén
- Department of Biomedical Science and Veterinary Public Health, Parasitology Unit, Swedish University of Agricultural Sciences, SE-750 07 Uppsala, Sweden
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11
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Nielsen MK, Leathwick DM, Sauermann CW. Shortened strongylid egg reappearance periods in horses following macrocyclic lactone administration - The impact on parasite dynamics. Vet Parasitol 2023; 320:109977. [PMID: 37352579 DOI: 10.1016/j.vetpar.2023.109977] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2023] [Revised: 06/16/2023] [Accepted: 06/17/2023] [Indexed: 06/25/2023]
Abstract
Over the past three decades, equine strongylid egg reappearance periods (ERPs) have shortened substantially for macrocyclic lactone anthelmintics. The ERPs of ivermectin and moxidectin were originally reported in the 8-10 and 12-16 week ranges, respectively, but several recent studies have found them to be around 4-5 weeks for both actives. This loss of several weeks of suppressed strongylid egg output could have substantial implications for parasite control. This study made use of a computer simulation model to evaluate the impact of shortened ERPs on the anthelmintic performance of ivermectin and moxidectin against equine cyathostomins. The original ERPs were set to 7.1 and 15.4 weeks for ivermectin and moxidectin, respectively, while the reduced ERP was set to 4.6 weeks for both actives. Simulations were set to compare model outputs between original and reduced ERP scenarios and results expressed as percent increase in strongylid egg output, infective third stage larvae on herbage (L3h), and encysted early third stage larvae (EL3). For each drug, simulations were evaluated for two different treatment scenarios (2 and 4 treatments annually), two different age groups (yearlings and adults), and for four different climates (cold humid continental, temperate oceanic, humid subtropical, and hot/cold semi-arid). Across all simulations, there was a substantial increase of the three evaluated parameters. With the ivermectin simulations, all three parameters increased in the 100-300% range across climates, age groups and treatment intensities. The moxidectin simulations displayed a wider range of results with parameters increasing from a few hundred to several thousand percent. The increases were most pronounced for L3h in the two cooler climates, reaching as high as 6727%. Overall, the loss of anthelmintic performance was at a magnitude of 10 times larger for moxidectin compared to ivermectin. This performance loss was climate dependent, and was also affected by treatment intensity, but not by horse age. This is the first study to evaluate consequences of shortened ERPs in horses and demonstrated a substantial loss in anthelmintic performance resulting from this development. The results illustrate that anthelmintic efficacy is more than the percent reduction of fecal egg counts at 14 days post treatment, and that substantial anthelmintic performance can be lost despite FECRTs remaining at 100%.
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Affiliation(s)
- Martin K Nielsen
- M.H. Gluck Equine Research Center, Department of Veterinary Science, University of Kentucky, Lexington, KY, USA.
| | - Dave M Leathwick
- AgResearch Grasslands, Private Bag, 11008, Palmerston North 4442, New Zealand
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12
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de Favare GM, de Almeida Cipriano I, do Carmo TA, Mena MO, Guelpa GJ, do Amarante AFT, de Soutello RVG. Anthelmintic resistance of horse strongyle nematodes to ivermectin in São Paulo state, Brazil. Vet Parasitol Reg Stud Reports 2023; 41:100864. [PMID: 37208071 DOI: 10.1016/j.vprsr.2023.100864] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2022] [Revised: 03/23/2023] [Accepted: 03/25/2023] [Indexed: 05/21/2023]
Abstract
The indiscriminate use of drugs to control gastrointestinal helminths in horses can lead to serious consequences for the animals, which represents a growing problem for health, animal welfare and productivity. Therefore, the present study aimed to evaluate the anthelmintic efficacy of ivermectin in naturally infected horses in the western region of the state of São Paulo. From May 2021 to April 2022, 123 naturally infected adult horses in 12 equine breeding farms (7 to 14 animals per farm) were evaluated with the fecal egg count reduction test. The horses had not been treated with anthelmintic drugs for at least 60 days before the start of the study. The animals were treated with ivermectin (0.2 mg/kg; Eqvalan®, Merial) administered orally according to recommended dosage by the manufacturer. Individual fecal samples were collected directly from the rectal ampulla and used to determine the eggs per gram of feces (EPG) and perform coproculture for identification of larvae on the day of anthelmintic treatment (D0) and 14 days later (D14). The fecal egg count reduction (FECR) on each property was calculated using the program Shiny-egg Counts R version 3.6.1, and the presence of anthelmintic resistance was confirmed when the FECR percentage was less than 95%, and when the lower confidence limit [LCI] was less than 90%. The pre-treatment average EPG count in the 12 properties was 991. In five properties the FECR was lower than 90%; in three properties between 90% and 95%; and in four properties equal to or greater than 95% after treatment with ivermectin. The occurrence of cyathostomins with resistance to ivermectin was recorded in the majority of the farms.
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Affiliation(s)
- Giordani Mascoli de Favare
- Universidade Estadual Paulista (UNESP), School of Agrarian and Technological Sciences (FCAT), Dracena, SP 17900-000, Brazil.
| | - Isabela de Almeida Cipriano
- Universidade Estadual Paulista (UNESP), School of Agrarian and Technological Sciences (FCAT), Dracena, SP 17900-000, Brazil
| | - Tábata Alves do Carmo
- Universidade Estadual Paulista (UNESP), School of Agrarian and Technological Sciences (FCAT), Dracena, SP 17900-000, Brazil
| | - Mateus Oliveira Mena
- Universidade Estadual Paulista (UNESP), School of Agrarian and Technological Sciences (FCAT), Dracena, SP 17900-000, Brazil
| | - Gabriel Jabismar Guelpa
- Universidade Estadual Paulista (UNESP), School of Agrarian and Technological Sciences (FCAT), Dracena, SP 17900-000, Brazil
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13
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Boisseau M, Dhorne-Pollet S, Bars-Cortina D, Courtot É, Serreau D, Annonay G, Lluch J, Gesbert A, Reigner F, Sallé G, Mach N. Species interactions, stability, and resilience of the gut microbiota - Helminth assemblage in horses. iScience 2023; 26:106044. [PMID: 36818309 PMCID: PMC9929684 DOI: 10.1016/j.isci.2023.106044] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2022] [Revised: 12/16/2022] [Accepted: 01/20/2023] [Indexed: 01/26/2023] Open
Abstract
The nature and strength of interactions entertained among helminths and their host gut microbiota remain largely unexplored. Using 40 naturally infected Welsh ponies, we tracked the gut microbiota-cyathostomin temporal dynamics and stability before and following anthelmintic treatment and the associated host blood transcriptomic response. High shedders harbored 14 species of cyathostomins, dominated by Cylicocyclus nassatus. They exhibited a highly diverse and temporal dynamic gut microbiota, with butyrate-producing Clostridia likely driving the ecosystem steadiness and host tolerance toward cyathostomins infection. However, anthelmintic administration sharply bent the microbial community. It disrupted the ecosystem stability and the time-dependent network of interactions, affecting longer term microbial resilience. These observations highlight how anthelmintic treatments alter the triangular relationship of parasite, host, and gut microbiota and open new perspectives for adding nutritional intervention to current parasite management strategies.
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Affiliation(s)
- Michel Boisseau
- , Université de Tours, INRAE, UMR1282 Infectiologie et Santé Publique, 37380 Nouzilly, France,IHAP, Université de Toulouse, INRAE, ENVT, 31076 Toulouse, France
| | - Sophie Dhorne-Pollet
- Université Paris-Saclay, INRAE, AgroParisTech, GABI, 78350 Jouy-en-Josas, France
| | - David Bars-Cortina
- Université Paris-Saclay, INRAE, AgroParisTech, GABI, 78350 Jouy-en-Josas, France
| | - Élise Courtot
- , Université de Tours, INRAE, UMR1282 Infectiologie et Santé Publique, 37380 Nouzilly, France
| | - Delphine Serreau
- , Université de Tours, INRAE, UMR1282 Infectiologie et Santé Publique, 37380 Nouzilly, France
| | - Gwenolah Annonay
- INRAE, US UMR 1426, Genomic platform, 31326 Castanet-Tolosan, France
| | - Jérôme Lluch
- INRAE, US UMR 1426, Genomic platform, 31326 Castanet-Tolosan, France
| | - Amandine Gesbert
- INRAE, UE Physiologie Animale de l’Orfrasière, 37380 Nouzilly, France
| | - Fabrice Reigner
- INRAE, UE Physiologie Animale de l’Orfrasière, 37380 Nouzilly, France
| | - Guillaume Sallé
- , Université de Tours, INRAE, UMR1282 Infectiologie et Santé Publique, 37380 Nouzilly, France,Corresponding author
| | - Núria Mach
- Université Paris-Saclay, INRAE, AgroParisTech, GABI, 78350 Jouy-en-Josas, France,IHAP, Université de Toulouse, INRAE, ENVT, 31076 Toulouse, France,Corresponding author
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14
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Macdonald SL, Abbas G, Ghafar A, Gauci CG, Bauquier J, El-Hage C, Tennent-Brown B, Wilkes EJA, Beasley A, Jacobson C, Cudmore L, Carrigan P, Hurley J, Beveridge I, Hughes KJ, Nielsen MK, Jabbar A. Egg reappearance periods of anthelmintics against equine cyathostomins: The state of play revisited. Int J Parasitol Drugs Drug Resist 2022; 21:28-39. [PMID: 36543048 PMCID: PMC10105024 DOI: 10.1016/j.ijpddr.2022.12.002] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2022] [Revised: 12/11/2022] [Accepted: 12/11/2022] [Indexed: 12/14/2022]
Abstract
Cyathostomins are the most common and highly prevalent parasites of horses worldwide. Historically, the control of cyathostomins has mainly relied on the routine use of anthelmintic products. Increasing reports on anthelmintic resistance (AR) in cyathostomins are concerning. A potential method proposed for detecting emerging AR in cyathostomins has been estimating the egg reappearance period (ERP). This paper reviews the data available for the ERP of cyathostomins against the three major classes of anthelmintics, macrocyclic lactones, tetrahydropyrimidines, and benzimidazoles. Published peer-reviewed original research articles were obtained from three databases (PubMed, CAB Direct and Web of Science) and were evaluated for their inclusion in a systematic review. Subsets of articles were then subjected to a review of ERP data. A total of 54 (of 134) studies published between 1972 and 2022 met the criteria for inclusion in the systematic review. Until the beginning of 2022, there was no agreed definition of the ERP; eight definitions of ERP were identified in the literature, complicating the comparison between studies. Additionally, potential risk factors for the shortening of the ERP, including previous anthelmintic use and climate, were frequently not described. Reports of shortened ERP for moxidectin and ivermectin are frequent: 20 studies that used comparable ERP definitions reported shortened moxidectin and ivermectin ERPs of 35 and 28 days, respectively. It is unclear whether the ERPs of these anthelmintics reduced to such levels are due to the development of AR or some biological factors related to horses, cyathostomin species, and/or the environment. The ERPs for other anthelmintics, such as fenbendazole and pyrantel, were frequently not reported due to established resistance against these drugs. Future research in horses is required to understand the mechanism(s) behind the shortening of ERP for cyathostomins. Based on this systematic review, we propose recommendations for future ERP studies.
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Affiliation(s)
- Stephanie L Macdonald
- Melbourne Veterinary School, Faculty of Veterinary and Agricultural Sciences, The University of Melbourne, Werribee, Victoria, Australia
| | - Ghazanfar Abbas
- Melbourne Veterinary School, Faculty of Veterinary and Agricultural Sciences, The University of Melbourne, Werribee, Victoria, Australia
| | - Abdul Ghafar
- Melbourne Veterinary School, Faculty of Veterinary and Agricultural Sciences, The University of Melbourne, Werribee, Victoria, Australia
| | - Charles G Gauci
- Melbourne Veterinary School, Faculty of Veterinary and Agricultural Sciences, The University of Melbourne, Werribee, Victoria, Australia
| | - Jenni Bauquier
- Melbourne Veterinary School, Faculty of Veterinary and Agricultural Sciences, The University of Melbourne, Werribee, Victoria, Australia
| | - Charles El-Hage
- Melbourne Veterinary School, Faculty of Veterinary and Agricultural Sciences, The University of Melbourne, Werribee, Victoria, Australia
| | - Brett Tennent-Brown
- Melbourne Veterinary School, Faculty of Veterinary and Agricultural Sciences, The University of Melbourne, Werribee, Victoria, Australia
| | | | - Anne Beasley
- School of Agriculture and Food Sciences, University of Queensland, Gatton, Queensland, Australia
| | - Caroline Jacobson
- Centre for Animal Production and Health, Murdoch University, Murdoch, Western Australia, Australia
| | - Lucy Cudmore
- Scone Equine Hospital, Scone, New South Wales, Australia
| | - Peter Carrigan
- Scone Equine Hospital, Scone, New South Wales, Australia
| | - John Hurley
- Swettenham Stud, Nagambie, Victoria, Australia
| | - Ian Beveridge
- Melbourne Veterinary School, Faculty of Veterinary and Agricultural Sciences, The University of Melbourne, Werribee, Victoria, Australia
| | - Kristopher J Hughes
- School of Animal and Veterinary Sciences, Charles Sturt University, Wagga Wagga, New South Wales, Australia
| | - Martin K Nielsen
- M.H. Gluck Equine Research Center, Department of Veterinary Science, University of Kentucky, Lexington, KY, USA
| | - Abdul Jabbar
- Melbourne Veterinary School, Faculty of Veterinary and Agricultural Sciences, The University of Melbourne, Werribee, Victoria, Australia.
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15
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World Association for the Advancement of Veterinary Parasitology (WAAVP): Second edition of guidelines for evaluating the efficacy of anthelmintics for dogs and cats. Vet Parasitol 2022; 312:109815. [DOI: 10.1016/j.vetpar.2022.109815] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2022] [Revised: 10/10/2022] [Accepted: 10/14/2022] [Indexed: 11/06/2022]
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16
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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. [PMID: 36244428 DOI: 10.1016/j.ijpara.2022.09.003] [Citation(s) in RCA: 18] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2022] [Revised: 09/02/2022] [Accepted: 09/04/2022] [Indexed: 11/05/2022]
Abstract
Macrocyclic lactones have been the most widely used drugs for equine parasite control during the past four decades. Unlike ivermectin, moxidectin exhibits efficacy against encysted cyathostomin larvae, and is reported to have persistent efficacy with substantially longer egg reappearance periods. However, shortened egg reappearance periods have been reported recently for both macrocyclic lactones, and these findings have raised several questions: (i) are egg reappearance period patterns different after ivermectin or moxidectin treatment? (ii) Are shortened egg reappearance periods associated with certain cyathostomin species or stages? (iii) How does moxidectin's larvicidal efficacy affect egg reappearance period? To address these questions, 36 horses at pasture, aged 2-5 years old, were randomly allocated to three treatment groups: 1, moxidectin; 2, ivermectin; and 3, untreated control. Strongylid fecal egg counts were measured on a weekly basis, and the egg reappearance period was 5 weeks for both compounds. Strongylid worm counts were determined for all horses: 18 were necropsied at 2 weeks post-treatment (PT), and the remaining 18 at 5 weeks PT. Worms were identified to species morphologically and by internal transcribed spacer-2 (ITS-2) rDNA metabarcoding. Moxidectin and ivermectin were 99.9% and 99.7% efficacious against adults at 2 weeks post treatment, whereas the respective efficacies against luminal L4s were 84.3% and 69.7%. At 5 weeks PT, adulticidal efficacy was 88.3% and 57.6% for moxidectin and ivermectin, respectively, while the efficacy against luminal L4s was 0% for both drugs. Moxidectin reduced early L3 counts by 18.1% and 8.0% at 2 or 5 weeks, while the efficacies against late L3s and mucosal L4s were 60.4% and 21.2% at the same intervals, respectively. The luminal L4s surviving ivermectin treatment were predominantly Cylicocyclus (Cyc.) insigne. The ITS-2 rDNA metabarcoding was in good agreement with morphologic species estimates but suggested differential activity between moxidectin and ivermectin for several species, most notably Cyc. insigne and Cylicocyclus nassatus. This study was a comprehensive investigation of current macrocyclic lactone efficacy patterns and provided important insight into potential mechanisms behind shortened egg reappearance periods.
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Affiliation(s)
- Martin K Nielsen
- M.H. Gluck Equine Research Center, Department of Veterinary Science, University of Kentucky, Lexington, KY, USA.
| | - Ashley E Steuer
- M.H. Gluck Equine Research Center, Department of Veterinary Science, University of Kentucky, Lexington, KY, USA
| | - Haley P Anderson
- M.H. Gluck Equine Research Center, Department of Veterinary Science, University of Kentucky, Lexington, KY, USA
| | - Stefan Gavriliuc
- Department of Ecosystem and Public Health, University of Calgary, Calgary, Alberta, Canada
| | - Alyssa B Carpenter
- M.H. Gluck Equine Research Center, Department of Veterinary Science, University of Kentucky, Lexington, KY, USA
| | - Elizabeth M Redman
- Department of Comparative Biology and Experimental Medicine, University of Calgary, Calgary, Alberta, Canada
| | - John S Gilleard
- Department of Comparative Biology and Experimental Medicine, University of Calgary, Calgary, Alberta, Canada
| | | | - Jocelyn Poissant
- Department of Ecosystem and Public Health, University of Calgary, Calgary, Alberta, Canada
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Anthelmintic resistance in equine nematodes: Current status and emerging trends. Int J Parasitol Drugs Drug Resist 2022; 20:76-88. [PMID: 36342004 PMCID: PMC9630620 DOI: 10.1016/j.ijpddr.2022.10.005] [Citation(s) in RCA: 31] [Impact Index Per Article: 15.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2022] [Revised: 10/19/2022] [Accepted: 10/20/2022] [Indexed: 11/06/2022]
Abstract
Anthelmintic resistance is reported in equine nematodes with increasing frequency in recent years, and no new anthelmintic classes have been introduced during the past 40 years. This manuscript reviews published literature describing anthelmintic resistance in cyathostomins, Parascaris spp., and Oxyuris equi with special emphasis on larvicidal efficacy against encysted cyathostomin larvae and strongylid egg reappearance periods (ERP). Resistance to benzimidazoles and pyrimidines is highly prevalent in cyathostomin populations around the world, and macrocyclic lactone resistance has been documented in cyathostomins in recent years as well. Two recent studies have documented resistance to the larvicidal regimen of fenbendazole, whereas the larvicidal efficacy of moxidectin is variable, but with no evidence of a reduction from historic levels. In the 1990s, ERP estimates were 8-10 and 12-16 weeks for ivermectin and moxidectin, respectively, while several studies published after year 2000 found ERPs to be 5 weeks for both compounds. This is a clear change in anthelmintic performance, but it remains unclear if this is due to development of anthelmintic resistance or selection for other biological traits leading to a quicker resumption of strongylid egg shedding following anthelmintic treatment. Macrocyclic lactone resistance is common in Parascaris spp. around the world, but recent reports suggests that resistance to the two other classes should be monitored as well. Finally, O. equi has been reported resistant to ivermectin and moxidectin in countries representing four continents. In conclusion, multi-drug resistance is becoming the norm in managed cyathostomin populations around the world, and a similar pattern may be emerging in Parascaris spp. More work is required to understand the mechanisms behind the shortened ERPs, and researchers and veterinarians around the world are encouraged to routinely monitor anthelmintic efficacy against equine nematodes.
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Smith MA, Carpenter AB, Nielsen MK. Precision of cyathostomin luminal worm counts: Investigation of storage duration and fixative. Vet Parasitol 2022; 309:109773. [DOI: 10.1016/j.vetpar.2022.109773] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2022] [Revised: 07/22/2022] [Accepted: 07/30/2022] [Indexed: 10/16/2022]
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Effect of sainfoin ( Onobrychis viciifolia) on cyathostomin eggs excretion, larval development, larval community structure, and efficacy of ivermectin treatment in horses. Parasitology 2022; 149:1439-1449. [PMID: 35929352 PMCID: PMC10090777 DOI: 10.1017/s0031182022000853] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Alternative strategies to chemical anthelmintics are needed for the sustainable control of equine strongylids. Bioactive forages like sainfoin (Onobrychis viciifolia) could contribute to reducing drug use, with the first hints of in vitro activity against cyathostomin free-living stages observed in the past. We analysed the effect of a sainfoin-rich diet on cyathostomin population and the efficacy of oral ivermectin treatment. Two groups of 10 naturally infected horses were enrolled in a 78-day experimental trial. Following a 1-week adaptation period, they were either fed with dehydrated sainfoin pellets (70% of their diet dry matter) or with alfalfa pellets (control group) for 21-days. No difference was found between the average fecal egg counts (FECs) of the two groups, but a significantly lower increase in larval development rate was observed for the sainfoin group, at the end of the trial. Quantification of cyathostomin species abundances with an ITS-2-based metabarcoding approach revealed that the sainfoin diet did not affect the nemabiome structure compared to the control diet. Following oral ivermectin treatment of all horses on day 21, the drug concentration was lower in horses fed with sainfoin, and cyathostomin eggs reappeared earlier in that group. Our results demonstrated that short-term consumption of a sainfoin-rich diet does not decrease cyathostomin FEC but seems to slightly reduce larval development. Consumption of dehydrated sainfoin pellets also negatively affected ivermectin pharmacokinetics, underscoring the need to monitor horse feeding regimes when assessing ivermectin efficacy in the field.
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Geurden T, Smith ER, Vercruysse J, Yazwinski T, Rehbein S, Nielsen MK. Reflections and future directions for continued development and refinement of guidelines for anthelmintic efficacy studies. Vet Parasitol 2022; 307-308:109741. [PMID: 35667202 DOI: 10.1016/j.vetpar.2022.109741] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2021] [Revised: 05/26/2022] [Accepted: 05/27/2022] [Indexed: 11/19/2022]
Abstract
This reflection paper complements the WAAVP (World Association for the Advancement of Veterinary Parasitology) general anthelmintic efficacy guideline, which outlines the general principles of anthelmintic efficacy evaluation across all animal host species. It provides background to the recommendations made in the WAAVP general anthelmintic efficacy guideline, with insights into the discussions leading to specific recommendations in the general guideline or the absence thereof. Furthermore, this paper discusses recent technological advancements with potential value to the evaluation of anthelmintic efficacy that may be considered for future versions of the general or species-specific guidelines if supported by sufficient levels of evidence. Finally, it also identifies potential research questions, such as the statistical approach for comparing worm counts between groups of animals.
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Affiliation(s)
| | - Emily R Smith
- Center for Veterinary Medicine, USA Food and Drug Administration, Rockville, USA
| | - Jozef Vercruysse
- Faculty of Veterinary Medicine, University of Gent, Salisburylaan 133, B-9820 Merelbeke, Belgium
| | - Tom Yazwinski
- Department of Animal Science, University of Arkansas, Fayetteville, AR, USA
| | - Steffen Rehbein
- Boehringer Ingelheim Vetmedica GmbH, Kathrinenhof Research Center, Rohrdorf, Germany
| | - Martin K Nielsen
- M.H. Gluck Equine Research Center, Department of Veterinary Science, University of Kentucky, Lexington, KY, USA
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World association for the advancement of veterinary parasitology (WAAVP) guideline for the evaluation of the efficacy of anthelmintics in food-producing and companion animals: general guidelines. Vet Parasitol 2022; 304:109698. [DOI: 10.1016/j.vetpar.2022.109698] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2022] [Accepted: 03/09/2022] [Indexed: 01/11/2023]
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