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McIntyre J, Miskell L, Morgan ER, Lovatt F, Laing R. Moxidectin use in Scottish sheep flocks suggests a need for clearer product labelling and communication of updated SCOPS guidelines. Vet Rec 2023; 192:e2083. [PMID: 36030372 PMCID: PMC10087414 DOI: 10.1002/vetr.2083] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2022] [Revised: 07/02/2022] [Accepted: 07/22/2022] [Indexed: 01/24/2023]
Abstract
BACKGROUND Guidelines for sustainable use of moxidectin were established in 2020. This study aimed to identify how Scottish sheep farmers are using this key endectocide and estimate its effectiveness against gastrointestinal nematodes. METHODS Questionnaires were distributed to sheep farmers across Scotland, and analysis focused on moxidectin use in relation to Sustainable Control of Parasites in Sheep (SCOPS) guidelines. Farmers using moxidectin in their flock volunteered to submit post-treatment sheep faecal samples, which were analysed for the presence of gastrointestinal nematodes using faecal egg counts with polymerase chain reaction to determine species. RESULTS Despite 70% of farmers using moxidectin in 2020, knowledge levels varied: 24% of farmers included other anthelmintics when asked about moxidectin use. Moxidectin was used for a wide variety of reasons, and most farmers did not consistently follow SCOPS guidelines. Despite only 2 of 76 farmers reporting failure of moxidectin treatment, gastrointestinal nematodes were found following moxidectin treatment on five out of six farms tested and included Teladorsagia circumcincta, Cooperia curticei, Haemonchus contortus and Nematodirus sp. CONCLUSION Findings from this project indicate the need for improved anthelmintic product labelling and farmer support to encourage sustainable use. The presence of nematodes in treated animals is suggestive of anthelmintic resistance.
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Affiliation(s)
- Jennifer McIntyre
- School of Biodiversity, One Health and Veterinary MedicineUniversity of GlasgowGlasgowUK
| | - Laura Miskell
- Institute for Global Food SecurityQueen's University BelfastBelfastUK
| | - Eric R. Morgan
- Institute for Global Food SecurityQueen's University BelfastBelfastUK
| | | | - Roz Laing
- School of Biodiversity, One Health and Veterinary MedicineUniversity of GlasgowGlasgowUK
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2
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Effectiveness of Anthelmintic Treatments in Small Ruminants in Germany. Animals (Basel) 2022; 12:ani12121501. [PMID: 35739838 PMCID: PMC9219448 DOI: 10.3390/ani12121501] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2022] [Revised: 06/04/2022] [Accepted: 06/07/2022] [Indexed: 11/17/2022] Open
Abstract
Simple Summary Parasitic worms are a major threat to the health and production of sheep and goats worldwide, particularly because many worms have become resistant to commonly applied drugs. This problem is well known around the world, but the situation is currently not well studied in Germany. This study was therefore performed to evaluate the effectiveness of treatments against infection with gastrointestinal nematodes. Faecal samples from animal groups were examined before and after treatment, the worm eggs in the feaces were counted, and the reduction in egg excretion following treatment was calculated. Eggs of Haemonchus contortus (barber’s pole worm) were stained to differentiate them from other gastrointestinal nematodes. Treatments were chosen and carried out by farmers together with their local veterinarian. Additional information was collected by questionnaires to check if the treatments were performed correctly. Reduced effectiveness was observed for all available drugs, but some showed better treatment success than others. The barber’s pole worm frequently survived treatments by most products. The high percentage of treatment failures is highly concerning, and it is necessary to develop and/or apply alternative methods of worm control to prevent the deterioration of this situation. Abstract Widespread anthelmintic resistance is a concern for small ruminant health and production worldwide. The current situation regarding anthelmintic efficacy is, however, not very well studied in Germany. Thus, a nationwide field study was undertaken to assess the effectiveness of 253 treatments performed in 223 small ruminant flocks by faecal egg count reduction test (FECRT) using pooled samples and a modified McMaster method. The percentage of Haemonchus contortus and non-Haemonchus eggs was determined by fluorescence microscopy following peanut agglutinin–fluorescein isothiocyanate staining. Treatments were chosen and performed by farmers together with their local veterinarian, and potentially confounding factors for FECRT results were addressed as far as possible by rigorous inclusion criteria. Reduced effectiveness was observed for treatments with all examined anthelmintic classes, but treatments with benzimidazoles and moxidectin showed significantly poorer results than monepantel, a closantel and mebendazole combination, and levamisole. Low case numbers precluded reliable assessment of avermectins. Unsuccessful treatments were frequently associated with the survival of H. contortus, but this was also observed for non-Haemonchus genera. The results are highly concerning, and sustainable approaches to parasite control are urgently needed to prevent further deterioration of this situation.
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Charlier J, Bartley DJ, Sotiraki S, Martinez-Valladares M, Claerebout E, von Samson-Himmelstjerna G, Thamsborg SM, Hoste H, Morgan ER, Rinaldi L. Anthelmintic resistance in ruminants: challenges and solutions. ADVANCES IN PARASITOLOGY 2022; 115:171-227. [PMID: 35249662 DOI: 10.1016/bs.apar.2021.12.002] [Citation(s) in RCA: 40] [Impact Index Per Article: 20.0] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Anthelmintic resistance (AR) is a growing concern for effective parasite control in farmed ruminants globally. Combatting AR will require intensified and integrated research efforts in the development of innovative diagnostic tests to detect helminth infections and AR, sustainable anthelmintic treatment strategies and the development of complementary control approaches such as vaccination and plant-based control. It will also require a better understanding of socio-economic drivers of anthelmintic treatment decisions, in order to support a behavioural shift and develop targeted communication strategies that promote the uptake of evidence-based sustainable solutions. Here, we review the state-of-the-art in these different fields of research activity related to AR in helminths of livestock ruminants in Europe and beyond. We conclude that in the advent of new challenges and solutions emerging from continuing spread of AR and intensified research efforts, respectively, there is a strong need for transnational multi-actor initiatives. These should involve all key stakeholders to develop indicators of infection and sustainable control, set targets and promote good practices to achieve them.
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Affiliation(s)
| | - D J Bartley
- Disease Control, Moredun Research Institute, Penicuik, United Kingdom
| | - S Sotiraki
- Veterinary Research Institute, Hellenic Agricultural Organisation ELGO-DIMITRA, Thessaloniki, Greece
| | - M Martinez-Valladares
- Instituto de Ganadería de Montaña (CSIC-Universidad de León), Departamento de Sanidad Animal, León, Spain
| | - E Claerebout
- Ghent University, Faculty of Veterinary Medicine, Laboratory of Parasitology, Merelbeke, Belgium
| | - G von Samson-Himmelstjerna
- Institute for Parasitology and Tropical Veterinary Medicine, Veterinary Centre for Resistance Research, Freie Universität Berlin, Berlin, Germany
| | - S M Thamsborg
- Veterinary Parasitology, University of Copenhagen, Frederiksberg C, Denmark
| | - H Hoste
- INRAE, UMR 1225 IHAP INRAE/ENVT, Toulouse University, Toulouse, France
| | - E R Morgan
- Institute for Global Food Security, Queen's University Belfast, Belfast, United Kingdom
| | - L Rinaldi
- University of Naples Federico II, Unit of Parasitology and Parasitic Diseases, Department of Veterinary Medicine and Animal Production, CREMOPAR, Napoli, Italy.
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4
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Teladorsagia Circumcincta Galectin-Mucosal Interactome in Sheep. Vet Sci 2021; 8:vetsci8100216. [PMID: 34679046 PMCID: PMC8540209 DOI: 10.3390/vetsci8100216] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2021] [Revised: 09/24/2021] [Accepted: 09/28/2021] [Indexed: 11/17/2022] Open
Abstract
Teladorsagia circumcincta is the most important gastrointestinal parasite in the livestock industry in temperate regions around the world, causing great economic losses. The infective third-stage larvae (L3) of Teladorsagia circumcincta secrete a large number of excretory-secretory (E/S) molecules, some of which are likely to play critical roles in modulating the host immune response. One of the most abundant E/S molecules is a protein termed Tci-gal-1, which has similarity to mammalian galectins. Galectins are a family of carbohydrate-binding molecules, with characteristic domain organisation and affinity for β-galactosids that mediate a variety of important cellular functions including inflammation and immune responses. To understand the role of Tci-gal-1 at the host–parasite interface, we used a proteomics pull-down approach to identify Tc-gal-1 interacting proteins from sheep abomasal scrapes and whole tissue. A total of 135 unique proteins were identified from whole abomasal tissue samples, while 89 proteins were isolated from abomasal scrape samples. Of these proteins, 63 were present in both samples. Many of the host proteins identified, such as trefoil factors and mucin-like proteins, play critical roles in the host response. The identification of Tci-gal-1 binding partners provides new insights on host–parasite interactions and could lead to the development of new control strategies.
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Turnbull F, Devaney E, Morrison AA, Laing R, Bartley DJ. Genotypic characterisation of monepantel resistance in historical and newly derived field strains of Teladorsagia circumcincta. Int J Parasitol Drugs Drug Resist 2019; 11:59-69. [PMID: 31622822 PMCID: PMC6796645 DOI: 10.1016/j.ijpddr.2019.10.002] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2019] [Revised: 10/02/2019] [Accepted: 10/04/2019] [Indexed: 11/24/2022]
Abstract
Recent reports of monepantel (MPTL) resistance in UK field isolates of Teladorsagia circumcincta has highlighted the need for a better understanding of the mechanism of MPTL-resistance in order to preserve its anthelmintic efficacy in this economically important species. Nine discrete populations of T. circumcincta were genotypically characterised; three MPTL-susceptible isolates, three experimentally selected MPTL-resistant strains and three field derived populations. Full-length Tci-mptl-1 gene sequences were generated and comparisons between the MPTL-susceptible isolates, MPTL-resistant strains and one field isolate, showed that different putative MPTL-resistance conferring mutations were present in different resistant isolates. Truncated forms of the Tci-mptl-1 gene were also observed. The genetic variability of individual larvae, within and between populations, was examined using microsatellite analyses at 10 'neutral' loci (presumed to be unaffected by MPTL). Results confirmed that there was little background genetic variation between the populations, global FST <0.038. Polymorphisms present in exons 7 and 8 of Tci-mptl-1 enabled genotyping of individual larvae. A reduction in the number of genotypes was observed in all MPTL-resistant strains compared to the MPTL-susceptible strains that they were derived from, suggesting there was purifying selection at Tci-mptl-1 as a result of MPTL-treatment. The potential link between benzimidazole (BZ)-resistance and MPTL-resistance was examined by screening individual larvae for the presence of three SNPs associated with BZ-resistance in the β-tubulin isotype-1 gene. The majority of larvae were BZ-susceptible homozygotes at positions 167 and 198. Increased heterozygosity at position 200 was observed in the MPTL-resistant strains compared to their respective MPTL-susceptible population. There was no decrease in the occurrence of BZ-resistant genotypes in larvae from each population. These differences, in light of the purifying selection at this locus in all MPTL-resistant isolates, suggests that Tci-mptl-1 confers MPTL-resistance in T. circumcincta, as in Haemonchus contortus, but that different mutations in Tci-mptl-1 can confer resistance in different populations.
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Affiliation(s)
- Frank Turnbull
- Institute of Biodiversity Animal Health and Comparative Medicine, University of Glasgow, Bearsden Road, Glasgow, G61 1QH, United Kingdom; Moredun Research Institute, Pentlands Science Park, Bush Loan, Edinburgh, EH26 0PZ, United Kingdom.
| | - Eileen Devaney
- Institute of Biodiversity Animal Health and Comparative Medicine, University of Glasgow, Bearsden Road, Glasgow, G61 1QH, United Kingdom
| | - Alison A Morrison
- Moredun Research Institute, Pentlands Science Park, Bush Loan, Edinburgh, EH26 0PZ, United Kingdom
| | - Roz Laing
- Institute of Biodiversity Animal Health and Comparative Medicine, University of Glasgow, Bearsden Road, Glasgow, G61 1QH, United Kingdom
| | - Dave J Bartley
- Moredun Research Institute, Pentlands Science Park, Bush Loan, Edinburgh, EH26 0PZ, United Kingdom
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6
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Sargison ND, MacLeay M, Morrison AA, Bartley DJ, Evans M, Chaudhry U. Development of amplicon sequencing for the analysis of benzimidazole resistance allele frequencies in field populations of gastrointestinal nematodes. INTERNATIONAL JOURNAL FOR PARASITOLOGY-DRUGS AND DRUG RESISTANCE 2019; 10:92-100. [PMID: 31425900 PMCID: PMC6708983 DOI: 10.1016/j.ijpddr.2019.08.003] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/07/2019] [Revised: 08/12/2019] [Accepted: 08/12/2019] [Indexed: 01/22/2023]
Abstract
Anthelmintic resistant gastrointestinal helminths have become a major cause of poor health in sheep and goats. Sensitive and specific molecular markers are needed to monitor the genotypic frequency of resistance in field parasite populations. Gastrointestinal nematode resistance to benzimidazole is caused by a mutation in one of three positions within the isotype 1 β-tubulin gene. In the absence of markers for resistance to the other broad spectrum anthelmintic classes, these provide a relevant study example. Determination of the prevalence of these single nucleotide polymorphisms in field nematode populations can be impractical using conventional molecular methods to examine individual parasites; which can be laborious and lack sensitivity in determining low levels of resistance in parasite populations. Here, we report the development of a novel method based on an Illumina MiSeq deep amplicon sequencing platform to sequence the isotype 1 β-tubulin locus of the small ruminant gastrointestinal nematode, Teladorsagia circumcincta, and determine the frequency of the benzimidazole resistance mutations. We validated the method by assessing sequence representation bias, comparing the results of Illumina MiSeq and pyrosequencing, and applying the method to populations containing known proportions of resistant and susceptible larvae. We applied the method to field samples collected from ewes and lambs on over a period of one year on three farms, each highlighting different aspects of sheep management and approaches to parasite control. The results show opportunities to build hypotheses with reference to selection pressures leading to differences in resistance allele frequencies between sampling dates, farms and ewes or lambs, and to consider the impact of their genetic fixation or otherwise. This study provides proof of concept of a practical, accurate, sensitive and scalable method to determine frequency of anthelmintic resistance mutations in gastrointestinal nematodes in field studies and as a management tool for livestock farmers.
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Affiliation(s)
- Neil D Sargison
- University of Edinburgh Roslin Institute and Royal (Dick) School of Veterinary Studies, Easter Bush Veterinary Centre, Roslin, Midlothian, EH25 9RG, United Kingdom
| | - Madison MacLeay
- University of Edinburgh Roslin Institute and Royal (Dick) School of Veterinary Studies, Easter Bush Veterinary Centre, Roslin, Midlothian, EH25 9RG, United Kingdom
| | - Alison A Morrison
- Moredun Research Institute, Pentlands Science Park, Bush Loan, Penicuik, EH26 0PZ, United Kingdom
| | - David J Bartley
- Moredun Research Institute, Pentlands Science Park, Bush Loan, Penicuik, EH26 0PZ, United Kingdom
| | - Mike Evans
- University of Edinburgh Roslin Institute and Royal (Dick) School of Veterinary Studies, Easter Bush Veterinary Centre, Roslin, Midlothian, EH25 9RG, United Kingdom
| | - Umer Chaudhry
- University of Edinburgh Roslin Institute and Royal (Dick) School of Veterinary Studies, Easter Bush Veterinary Centre, Roslin, Midlothian, EH25 9RG, United Kingdom.
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7
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Cazajous T, Prevot F, Kerbiriou A, Milhes M, Grisez C, Tropee A, Godart C, Aragon A, Jacquiet P. Multiple-resistance to ivermectin and benzimidazole of a Haemonchus contortus population in a sheep flock from mainland France, first report. VETERINARY PARASITOLOGY- REGIONAL STUDIES AND REPORTS 2018; 14:103-105. [PMID: 31014712 DOI: 10.1016/j.vprsr.2018.09.005] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/17/2018] [Revised: 08/20/2018] [Accepted: 09/13/2018] [Indexed: 11/29/2022]
Abstract
Anthelmintic resistance was explored by fecal egg count reduction test in a sheep flock from the French Pyrenees at the request of the veterinary practitioner after a poor response to anthelmintics was noted. The FECRT confirmed the suspicion with a mean percentage of reduction in egg excretions of 45% (CI 95%: - 40 to 78.5) and 0% (CI95%: - 162 to 49) within the ivermectin and the benzimidazole groups respectively. Haemonchus contortus was shown to be the IVM and BZ resistant species after morphological and molecular characterizations whereas Teladorsagia circumcincta was probably resistant to BZ only. The H. contortus population was still susceptible to moxidectin, closantel and levamisole. As this sheep flock is a transhumant flock, the spread of this multiple-resistant Haemonchus contortus population to the other sheep flocks sharing the same pastures in Pyrenean Mountains is highly likely. From the knowledge of the authors, this is the first report of multi-resistance to ivermectin and benzimidazole of a Haemonchus contortus population in mainland France.
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Affiliation(s)
- T Cazajous
- Selarl vétérinaire du piémont, Zone commerciale espace Pyrénées, 64800, Mirepeix, France
| | - F Prevot
- UMT Santé des Petits Ruminants, UMR INRA/ENVT, 1225 Interactions Hôtes Agents Pathogènes, Ecole Nationale Vétérinaire, 23, chemin des Capelles, BP 87614, 31 076 Toulouse, Cedex 03, France
| | - A Kerbiriou
- UMT Santé des Petits Ruminants, UMR INRA/ENVT, 1225 Interactions Hôtes Agents Pathogènes, Ecole Nationale Vétérinaire, 23, chemin des Capelles, BP 87614, 31 076 Toulouse, Cedex 03, France
| | - M Milhes
- UMT Santé des Petits Ruminants, UMR INRA/ENVT, 1225 Interactions Hôtes Agents Pathogènes, Ecole Nationale Vétérinaire, 23, chemin des Capelles, BP 87614, 31 076 Toulouse, Cedex 03, France
| | - C Grisez
- UMT Santé des Petits Ruminants, UMR INRA/ENVT, 1225 Interactions Hôtes Agents Pathogènes, Ecole Nationale Vétérinaire, 23, chemin des Capelles, BP 87614, 31 076 Toulouse, Cedex 03, France
| | - A Tropee
- UMT Santé des Petits Ruminants, UMR INRA/ENVT, 1225 Interactions Hôtes Agents Pathogènes, Ecole Nationale Vétérinaire, 23, chemin des Capelles, BP 87614, 31 076 Toulouse, Cedex 03, France
| | - C Godart
- UMT Santé des Petits Ruminants, UMR INRA/ENVT, 1225 Interactions Hôtes Agents Pathogènes, Ecole Nationale Vétérinaire, 23, chemin des Capelles, BP 87614, 31 076 Toulouse, Cedex 03, France
| | - A Aragon
- UMT Santé des Petits Ruminants, UMR INRA/ENVT, 1225 Interactions Hôtes Agents Pathogènes, Ecole Nationale Vétérinaire, 23, chemin des Capelles, BP 87614, 31 076 Toulouse, Cedex 03, France
| | - P Jacquiet
- UMT Santé des Petits Ruminants, UMR INRA/ENVT, 1225 Interactions Hôtes Agents Pathogènes, Ecole Nationale Vétérinaire, 23, chemin des Capelles, BP 87614, 31 076 Toulouse, Cedex 03, France.
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8
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Glover M, Clarke C, Nabb L, Schmidt J. Anthelmintic efficacy on sheep farms in south-west England. Vet Rec 2017; 180:378. [DOI: 10.1136/vr.104151] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/02/2017] [Indexed: 11/04/2022]
Affiliation(s)
- M. Glover
- Torch Farm & Equine Ltd, Horsepond Meadow; South Molton Devon EX36 4EJ UK
| | - C. Clarke
- Torch Farm & Equine Ltd, Horsepond Meadow; South Molton Devon EX36 4EJ UK
| | - L. Nabb
- Torch Farm & Equine Ltd, Horsepond Meadow; South Molton Devon EX36 4EJ UK
| | - J. Schmidt
- Torch Farm & Equine Ltd, Horsepond Meadow; South Molton Devon EX36 4EJ UK
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9
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Jack C, Hotchkiss E, Sargison ND, Toma L, Milne C, Bartley DJ. A quantitative analysis of attitudes and behaviours concerning sustainable parasite control practices from Scottish sheep farmers. Prev Vet Med 2017; 139:134-145. [PMID: 28233581 DOI: 10.1016/j.prevetmed.2017.01.018] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2016] [Revised: 01/30/2017] [Accepted: 01/31/2017] [Indexed: 11/15/2022]
Abstract
Nematode control in sheep, by strategic use of anthelmintics, is threatened by the emergence of roundworms populations that are resistant to one or more of the currently available drugs. In response to growing concerns of Anthelmintic Resistance (AR) development in UK sheep flocks, the Sustainable Control of Parasites in Sheep (SCOPS) initiative was set up in 2003 in order to promote practical guidelines for producers and advisors. To facilitate the uptake of 'best practice' approaches to nematode management, a comprehensive understanding of the various factors influencing sheep farmers' adoption of the SCOPS principles is required. A telephone survey of 400 Scottish sheep farmers was conducted to elicit attitudes regarding roundworm control, AR and 'best practice' recommendations. A quantitative statistical analysis approach using structural equation modelling was chosen to test the relationships between both observed and latent variables relating to general roundworm control beliefs. A model framework was developed to test the influence of socio-psychological factors on the uptake of sustainable (SCOPS) and known unsustainable (AR selective) roundworm control practices. The analysis identified eleven factors with significant influences on the adoption of SCOPS recommended practices and AR selective practices. Two models established a good fit with the observed data with each model explaining 54% and 47% of the variance in SCOPS and AR selective behaviours, respectively. The key influences toward the adoption of best practice parasite management, as well as demonstrating negative influences on employing AR selective practices were farmer's base line understanding about roundworm control and confirmation about lack of anthelmintic efficacy in a flock. The findings suggest that improving farmers' acceptance and uptake of diagnostic testing and improving underlying knowledge and awareness about nematode control may influence adoption of best practice behaviour.
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Affiliation(s)
- Corin Jack
- Disease control, Moredun Research Institute,Pentlands Science Park, Bush Loan, Penicuik, EH26 0PZ, UK.
| | - Emily Hotchkiss
- Disease control, Moredun Research Institute,Pentlands Science Park, Bush Loan, Penicuik, EH26 0PZ, UK
| | - Neil D Sargison
- Royal (Dick) School of Veterinary Studies, University of Edinburgh, Easter Bush Campus, Midlothian, EH25 9RG, UK
| | - Luiza Toma
- Scotland's Rural College (SRUC), Peter Wilson Building, Kings Buildings, West Mains Road, Edinburgh EH9 3JG, UK
| | - Catherine Milne
- Scotland's Rural College (SRUC), Peter Wilson Building, Kings Buildings, West Mains Road, Edinburgh EH9 3JG, UK
| | - David J Bartley
- Disease control, Moredun Research Institute,Pentlands Science Park, Bush Loan, Penicuik, EH26 0PZ, UK
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10
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Das BK, Tokunaga E, Harada K, Sumii Y, Shibata N. Diastereoselective synthesis of fluoroisosteric analogues of antiparasitic pyrrolobenzoxazine alkaloids from tryptophan by successive fluorination–cyclization and a Meisenheimer-type rearrangement. Org Chem Front 2017. [DOI: 10.1039/c7qo00234c] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Fluoroisosteric analogues of an antiparasitic pyrrolobenzoxazine alkaloid CJ-12663 were designed and diastereoselectively synthesized.
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Affiliation(s)
- Biplab Kumar Das
- Department of Nanopharmaceutical Sciences
- Nagoya Institute of Technology
- Nagoya 466-8555
- Japan
| | - Etsuko Tokunaga
- Department of Nanopharmaceutical Sciences
- Nagoya Institute of Technology
- Nagoya 466-8555
- Japan
| | - Kyosuke Harada
- Department of Nanopharmaceutical Sciences
- Nagoya Institute of Technology
- Nagoya 466-8555
- Japan
| | - Yuji Sumii
- Department of Nanopharmaceutical Sciences
- Nagoya Institute of Technology
- Nagoya 466-8555
- Japan
| | - Norio Shibata
- Department of Nanopharmaceutical Sciences
- Nagoya Institute of Technology
- Nagoya 466-8555
- Japan
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11
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Laing R, Maitland K, Lecová L, Skuce PJ, Tait A, Devaney E. Analysis of putative resistance gene loci in UK field populations of Haemonchus contortus after 6years of macrocyclic lactone use. Int J Parasitol 2016; 46:621-30. [PMID: 27179994 PMCID: PMC5011429 DOI: 10.1016/j.ijpara.2016.03.010] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2016] [Revised: 03/25/2016] [Accepted: 03/30/2016] [Indexed: 11/27/2022]
Abstract
Sheep farmers in the UK rely on strategic anthelmintic use to treat and control gastrointestinal roundworms in their flocks. However, resistance to these drugs is now widespread and threatens the sustainability of sheep production. The mechanisms underlying resistance to the most commonly used class, the macrocyclic lactones, are not known and sensitive diagnostic tools based on molecular markers are not currently available. This prohibits accurate surveillance of resistance or assessment of strategies aimed at controlling its spread. In this study, we examined four UK field populations of Haemonchus contortus, differing in macrocyclic lactone treatment history, for evidence of selection at 'candidate gene' loci identified as determining macrocyclic lactone resistance in previously published research. Individual worms were genotyped at Hc-lgc-37, Hc-glc-5, Hc-avr-14 and Hc-dyf-7, and four microsatellite loci. High levels of polymorphism were identified at the first three candidate gene loci with remarkably little polymorphism at Hc-dyf-7. While some between-population comparisons of individual farms with and without long-term macrocyclic lactone use identified statistically significant differences in allele frequency and/or fixation index at the Hc-lgc-37, Hc-glc-5 or Hc-avr-14 loci, we found no consistent evidence of selection in other equivalent comparisons. While it is possible that different mechanisms are important in different populations or that resistance may be conferred by small changes at multiple loci, our findings suggest that these are unlikely to be major loci conferring macrocyclic lactone resistance on UK farms or suitable for diagnostic marker development. More powerful approaches, using genome-wide or whole genome sequencing, may be required to define macrocyclic lactone resistance loci in such genetically variable populations.
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Affiliation(s)
- Roz Laing
- Institute of Biodiversity, Animal Health and Comparative Medicine, College of Medical, Veterinary and Life Sciences, University of Glasgow, Scotland, UK.
| | - Kirsty Maitland
- Institute of Biodiversity, Animal Health and Comparative Medicine, College of Medical, Veterinary and Life Sciences, University of Glasgow, Scotland, UK
| | - Lenka Lecová
- Department of Tropical Medicine, First Faculty of Medicine, Charles University in Prague, Czech Republic
| | - Philip J Skuce
- Moredun Research Institute, Pentlands Science Park, Penicuik, UK
| | - Andy Tait
- Institute of Biodiversity, Animal Health and Comparative Medicine, College of Medical, Veterinary and Life Sciences, University of Glasgow, Scotland, UK
| | - Eileen Devaney
- Institute of Biodiversity, Animal Health and Comparative Medicine, College of Medical, Veterinary and Life Sciences, University of Glasgow, Scotland, UK
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12
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13
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Patterns of faecal nematode egg shedding after treatment of sheep with a long-acting formulation of moxidectin. Vet Parasitol 2015; 212:275-80. [DOI: 10.1016/j.vetpar.2015.07.014] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2015] [Revised: 07/13/2015] [Accepted: 07/14/2015] [Indexed: 11/20/2022]
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Selection and characterisation of monepantel resistance in Teladorsagia circumcincta isolates. INTERNATIONAL JOURNAL FOR PARASITOLOGY-DRUGS AND DRUG RESISTANCE 2015; 5:69-76. [PMID: 26042197 PMCID: PMC4443404 DOI: 10.1016/j.ijpddr.2015.05.001] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/01/2014] [Revised: 05/05/2015] [Accepted: 05/06/2015] [Indexed: 11/22/2022]
Abstract
Monepantel resistance was selected in three isolates of Teladorsagia circumcincta. Selection for resistance was generated through rounds of sub-optimal dosing. Selection for monepantel resistance occurred within 9–13 generations. Selection for resistance impacted on the life history traits of the isolates. Increased egg output and shortened time to patency was seen in a resistant isolate.
Monepantel (MPTL) is one of two new anthelmintic compounds introduced onto the sheep market to control gastro-intestinal nematodes. Resistance to this compound is rare but has been reported. In order to preserve the efficacy of this and other anthelmintics, it is essential to understand both (a) the mechanisms involved in the selection of resistance and (b) how the parasites evolve to deal with these compounds. To address these questions three MPTL-resistant Teladorsagia circumcincta isolates (MTci2-11, MTci5-13 and MTci7-12) have been artificially selected in vivo from phenotypically characterised parent isolates (MTci2, MTci5, MTci7 respectively). The selection process involved collecting and culturing eggs from surviving worms from sheep administered sub-optimal dosages of MPTL (Zolvix®) to provide infective larvae to infect further sheep until resistant isolates were generated (between 9 and 13 rounds of selection). A controlled efficacy test was conducted using the original parental isolates and the newly generated MPTL resistant isolates (n = 5 per group). Selected isolates were assessed both under anthelmintic stress (Zolvix®, 2.5 mg/kg bodyweight; MTci-MPTL) and at rest (untreated, MTci-CON). A number of life-history traits were assessed, namely, worm establishment rates, time to patency, faecal egg output, body length of adults and eggs in utero. The estimated resistance status of the selected isolates was confirmed with 48%, 28% and 9% reductions in worm burden at 7-days post Zolvix® administration for MTci2-11-MPTL, MTci5-13-MPTL and MTci7-12-MPTL, respectively, compared with untreated controls. One of the selected isolates MTci7-12-CON showed significantly greater total worm burden (p = 0.025), greater establishment rate (p = 0.033), decreased time to patency (p = 0.048), higher cumulative egg outputs (p = 0.002) compared with its parental derivative MTci7. The trial results suggest that anthelmintic selection in T. circumcincta, albeit under experimental conditions, can select for more prolific/fecund and quicker maturing populations. These data provide an insight into how parasites evolve in response to anthelmintic pressure.
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Marr EJ, Sargison ND, Nisbet AJ, Burgess STG. RNA interference for the identification of ectoparasite vaccine candidates. Parasite Immunol 2015; 36:616-26. [PMID: 25065384 DOI: 10.1111/pim.12132] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2014] [Accepted: 07/23/2014] [Indexed: 12/21/2022]
Abstract
Ectoparasites present a major challenge for disease management globally. With drug resistance increasingly observed in many disease-causing species, the need for novel control measures is pressing. Ever-expanding genomic resources from 'next generation' sequencing are now available for a number of arthropod ectoparasites, necessitating an effective means of screening these data for novel candidates for vaccine antigens or targets for chemotherapeutics. Such in vitro screening methods must be developed if we are to make discoveries in a timely and cost-effective manner. This review will discuss the potential that RNA interference (RNAi) has demonstrated thus far in the context of arthropod ectoparasites and the potential roles for this technology in the development of novel methods for parasite control.
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Affiliation(s)
- E J Marr
- Division of Vaccines and Diagnostics, Pentlands Science Park, Moredun Research Institute, Bush Loan, Penicuik, Edinburgh, UK; Royal (Dick) School of Veterinary Studies, University of Edinburgh, Easter Bush, Roslin, Midlothian, UK
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Chintoan-Uta C, Morgan ER, Skuce PJ, Coles GC. Wild deer as potential vectors of anthelmintic-resistant abomasal nematodes between cattle and sheep farms. Proc Biol Sci 2014; 281:20132985. [PMID: 24552838 PMCID: PMC4027391 DOI: 10.1098/rspb.2013.2985] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Gastrointestinal (GI) nematodes are among the most important causes of production loss in farmed ruminants, and anthelmintic resistance is emerging globally. We hypothesized that wild deer could potentially act as reservoirs of anthelmintic-resistant GI nematodes between livestock farms. Adult abomasal nematodes and faecal samples were collected from fallow (n = 24), red (n = 14) and roe deer (n = 10) from venison farms and areas of extensive or intensive livestock farming. Principal components analysis of abomasal nematode species composition revealed differences between wild roe deer grazing in the areas of intensive livestock farming, and fallow and red deer in all environments. Alleles for benzimidazole (BZ) resistance were identified in β-tubulin of Haemonchus contortus of roe deer and phenotypic resistance confirmed in vitro by an egg hatch test (EC50 = 0.149 µg ml−1 ± 0.13 µg ml−1) on H. contortus eggs from experimentally infected sheep. This BZ-resistant H. contortus isolate also infected a calf experimentally. We present the first account of in vitro BZ resistance in wild roe deer, but further experiments should firmly establish the presence of phenotypic BZ resistance in vivo. Comprehensive in-field studies should assess whether nematode cross-transmission between deer and livestock occurs and contributes, in any way, to the development of resistance on livestock farms.
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Affiliation(s)
- C Chintoan-Uta
- School of Veterinary Sciences, University of Bristol, , Bristol BS40 5DU, UK, Moredun Research Institute, , Penicuik EH26 0PZ, UK
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Geurden T, Hoste H, Jacquiet P, Traversa D, Sotiraki S, Frangipane di Regalbono A, Tzanidakis N, Kostopoulou D, Gaillac C, Privat S, Giangaspero A, Zanardello C, Noé L, Vanimisetti B, Bartram D. Anthelmintic resistance and multidrug resistance in sheep gastro-intestinal nematodes in France, Greece and Italy. Vet Parasitol 2014; 201:59-66. [PMID: 24560365 DOI: 10.1016/j.vetpar.2014.01.016] [Citation(s) in RCA: 72] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2013] [Revised: 01/03/2014] [Accepted: 01/21/2014] [Indexed: 11/17/2022]
Abstract
Anthelmintic resistance (AR) in ovine gastro-intestinal nematodes has been reported to affect the health and productivity of sheep globally. The objective of the present study was to evaluate the efficacy of commonly used oral drenches in sheep in France, Greece and Italy. In each country, 10 farms were selected. On each farm, 50 animals were blocked based on the pre-treatment faecal egg count (FEC). Within each block, animals were randomly allocated to one of 5 treatment groups. In addition to an untreated control group, there were 4 groups treated per oral route: moxidectin (MOX) and ivermectin (IVM), both at 0.2mg/kg bodyweight, levamisole (LEV; at 7.5mg/kg bodyweight) and a benzimidazole (BZ; at 3.75-5mg/kg bodyweight). In France, animals were not treated with LEV, but with netobimin (NET; at 7.5mg/kg bodyweight). The FEC was monitored using a modified McMaster technique. Two weeks after treatment, individual faecal samples were taken from all animals and efficacy was calculated as the difference between arithmetic mean FEC of the control group versus each respective treatment group. The results of the present study indicate the high efficacy of treatment with oral formulations of MOX (99-100%) and IVM (98-100%) on all farms, except on 1 farm in Greece. On this farm, multi drug resistance (MDR) was identified involving 4 anthelmintics (efficacy MOX: 91%; IVM: 0%; BZ: 58% and LEV: 87%). In Greece and Italy, AR against LEV and BZ was observed on some farms, with MDR involving both anthelmintics on 3 farms in Greece and on 2 farms in Italy. In France, AR against BZ and NET was observed on all 10 farms included. In all countries, Teladorsagia sp. was the most common nematode larva identified after treatment, followed by Haemonchus sp. and Trichostrongylus sp., with differences among farms and treatments. The current study confirms the high efficacy of oral treatments with MOX and IVM, even on farms with worm populations resistant to BZ, LEV or NET. This study also reports MDR against 4 anthelmintics on one farm in Greece.
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Affiliation(s)
- Thomas Geurden
- Zoetis, Veterinary Medicine Research and Development, Mercuriusstraat 20, 1930 Zaventem, Belgium.
| | - Herve Hoste
- Institut National de la Recherche Agronomique/UMT Maîtrise de la Santé des Troupeaux de Petits Ruminants/Ecole Nationale Vétérinaire de Toulouse, Toulouse cedex, France
| | - Philippe Jacquiet
- Institut National de la Recherche Agronomique/UMT Maîtrise de la Santé des Troupeaux de Petits Ruminants/Ecole Nationale Vétérinaire de Toulouse, Toulouse cedex, France
| | - Donato Traversa
- University of Teramo, Faculty of Veterinary Medicine, Teramo, Italy
| | - Smaragda Sotiraki
- Veterinary Research Institute - Hellenic Agricultural Organization-Demeter (former NAGREF), Thessaloniki, Greece
| | | | - Nikolaos Tzanidakis
- Veterinary Research Institute - Hellenic Agricultural Organization-Demeter (former NAGREF), Thessaloniki, Greece
| | - Despoina Kostopoulou
- Veterinary Research Institute - Hellenic Agricultural Organization-Demeter (former NAGREF), Thessaloniki, Greece
| | - Christie Gaillac
- Institut National de la Recherche Agronomique/UMT Maîtrise de la Santé des Troupeaux de Petits Ruminants/Ecole Nationale Vétérinaire de Toulouse, Toulouse cedex, France
| | - Simon Privat
- Institut National de la Recherche Agronomique/UMT Maîtrise de la Santé des Troupeaux de Petits Ruminants/Ecole Nationale Vétérinaire de Toulouse, Toulouse cedex, France
| | - Annunziata Giangaspero
- University of Foggia, Department of Science of Agriculture, Food and Environment, Foggia, Italy
| | - Claudia Zanardello
- Istituto Zooprofilattico Sperimentale delle Venezie, Legnaro, Padova, Italy
| | - Laura Noé
- Zoetis, Veterinary Medicine Research and Development, Mercuriusstraat 20, 1930 Zaventem, Belgium
| | - Bindu Vanimisetti
- Zoetis, Veterinary Medicine Research and Development, Kalamazoo, MI, USA
| | - David Bartram
- Zoetis, 23/25 avenue du Docteur Lannelongue, 75668 Paris Cedex 14, France
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Roberts B, Antonopoulos A, Haslam SM, Dicker AJ, McNeilly TN, Johnston SL, Dell A, Knox DP, Britton C. Novel expression of Haemonchus contortus vaccine candidate aminopeptidase H11 using the free-living nematode Caenorhabditis elegans. Vet Res 2013; 44:111. [PMID: 24289031 PMCID: PMC4176091 DOI: 10.1186/1297-9716-44-111] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2013] [Accepted: 11/19/2013] [Indexed: 11/28/2022] Open
Abstract
With the problem of parasitic nematode drug resistance increasing, vaccine development offers an alternative sustainable control approach. For some parasitic nematodes, native extracts enriched for specific proteins are highly protective. However, recombinant forms of these proteins have failed to replicate this protection. This is thought to be due to differences in glycosylation and/or conformation between native and recombinant proteins. We have exploited the free-living nematode Caenorhabditis elegans to examine its suitability as an alternative system for recombinant expression of parasitic nematode vaccine candidates. We focussed on Haemonchus contortus aminopeptidase H11 glycoprotein, which is enriched in a gut membrane fraction capable of inducing significant protection against this important ovine gastrointestinal nematode. We show that H. contortus H11 expressed in C. elegans is enzymatically active and MALDI mass spectrometry identifies similar di- and tri-fucosylated structures to those on native H11, with fucose at the 3- and/or 6-positions of the proximal GlcNAc. Some glycan structural differences were observed, such as lack of LDNF. Serum antibody to native H11 binds to C. elegans recombinant H11 and most of the antibody to rH11 or native H11 is directed to glycan moieties. Despite these similarities, no reduction in worm burden or faecal egg count was observed following immunisation of sheep with C. elegans-expressed recombinant H11 protein. The findings suggest that the di- and tri-fucosylated N-glycans expressed on rH11 do not contribute to the protective effect of H11 and that additional components present in native H11-enriched extract are likely required for enhancing the antibody response necessary for protection.
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Affiliation(s)
- Brett Roberts
- Institute of Infection, Immunity and Inflammation, College of Medical, Veterinary and Life Sciences, University of Glasgow, Bearsden Road, Glasgow G61 1QH, UK.
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Animal health aspects of adaptation to climate change: beating the heat and parasites in a warming Europe. Animal 2013; 7 Suppl 2:333-45. [PMID: 23739475 DOI: 10.1017/s175173111300075x] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Weather patterns in northern European regions have changed noticeably over the past several decades, featuring warmer, wetter weather with more extreme events. The climate is projected to continue on this trajectory for the foreseeable future, even under the most modest warming scenarios. Such changes will have a significant impact on livestock farming, both directly through effects on the animals themselves, and indirectly through changing exposure to pests and pathogens. Adaptation options aimed at taking advantage of new opportunities and/or minimising the risks of negative impacts will, in themselves, have implications for animal health and welfare. In this review, we consider the potential consequences of future intensification of animal production, challenges associated with indoor and outdoor rearing of animals and aspects of animal transportation as key examples. We investigate the direct and indirect effects of climate change on the epidemiology of important livestock pathogens, with a particular focus on parasitic infections, and the likely animal health consequences associated with selected adaptation options. Finally, we attempt to identify key gaps in our knowledge and suggest future research priorities.
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Detection of benzimidazole resistance in gastrointestinal nematodes of sheep and goats of sub-Himalyan region of northern India using different tests. Vet Parasitol 2013; 198:312-8. [PMID: 24126090 DOI: 10.1016/j.vetpar.2013.09.018] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2013] [Revised: 08/30/2013] [Accepted: 09/16/2013] [Indexed: 11/22/2022]
Abstract
The present investigation was planned with the objective of studying the status of benzimidazole (BZ) resistance in gastrointestinal nematodes (GIN) of sheep and goats of different agro-climatic zones of sub-Himalyan region of northern India using in vivo faecal egg count reduction test (FECRT) and in vitro tests namely egg hatch assay (EHA) and larval development assay (LDA). Out of fourteen flocks, FECRT detected resistance in eight flocks (two sheep flocks and six goat flocks) with FECR% ranging from 54.95 to 90.86. Pre treatment coproculture contained predominantly Haemonchus contortus, followed by Trichostrongylus spp., Oesophagostomum and Strongyloides, while post treatment coproculture results showed that only H. contortus survived fenbendazole (FBZ) (in FECRT) or thiabendazole (TBZ) (in LDA) treatment except in three flocks of Tarai region {one sheep flock (Us1), and two goat flocks (Ug1 and Ug5)} where BZ resistant Trichostrongylus were also detected. The GIN of those eight farms which were found resistant by FECRT were also detected resistant by EHA. Arithmetic mean and range of ED50 value of susceptible group was found to be 0.059 μg/ml and 0.037-0.096 μg/ml, respectively, and the same for the resistant group were found to be 0.119 μg/ml and 0.101-0.147 μg/ml, respectively. With LDA, the arithmetic mean and range of LC50 value of susceptible group was found 0.0030 μg/ml and 0.001-0.005 μg/ml, respectively, and those of resistant group was found 0.0105 μg/ml and 0.009-0.012 μg/ml, respectively. The values of Spearman rank correlation coefficient indicated that negative correlation was found between FECR% and ED50 and between FECR% and LC50 while positive correlation existed between ED50 and LC50 value and the p-values indicated that these correlations were statistically highly significant. In the present study, FECRT and EHA gave comparable results with regard to detection of BZ resistance in GIN in sheep and goats. Although with LDA, the threshold LC50 value could not be established as for EHA but LDA indicated the presence of low level of resistance in GIN of both sheep and goats. For effective worm control, regular monitoring for anthelmintic resistance is important to know the status of anthelmintic efficacy in a particular agro-climatic zone. The baseline information thus generated will enable timely management of benzimidazoles resistance in GIN.
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21
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Understanding the epidemiology of gastrointestinal parasitic infections in sheep: What does a faecal helminth egg count tell us? Small Rumin Res 2013. [DOI: 10.1016/j.smallrumres.2012.11.008] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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22
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McMahon C, Barley J, Edgar H, Ellison S, Hanna R, Malone F, Brennan G, Fairweather I. Anthelmintic resistance in Northern Ireland (II): Variations in nematode control practices between lowland and upland sheep flocks. Vet Parasitol 2013; 192:173-82. [DOI: 10.1016/j.vetpar.2012.10.022] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2012] [Revised: 10/26/2012] [Accepted: 10/31/2012] [Indexed: 10/27/2022]
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McMahon C, Bartley DJ, Edgar HWJ, Ellison SE, Barley JP, Malone FE, Hanna REB, Brennan GP, Fairweather I. Anthelmintic resistance in Northern Ireland (I): prevalence of resistance in ovine gastrointestinal nematodes, as determined through faecal egg count reduction testing. Vet Parasitol 2013; 195:122-30. [PMID: 23398988 DOI: 10.1016/j.vetpar.2013.01.006] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2012] [Revised: 01/06/2013] [Accepted: 01/13/2013] [Indexed: 11/16/2022]
Abstract
The prevalence of anthelmintic resistance in Northern Ireland sheep flocks was evaluated between July and October 2011. Sampling kits were sent to 172 flock owners and returns were received from 91. Within this survey population, 27 flock owners used benzimidazole products, 10 used levamisole products, 15 used avermectin products, 26 used milbemycin products and 4 flock owners used the amino acetonitrile derivative, Monepantel. The remaining 9 flock owners used combination drenches (broad spectrum wormer plus fasciolicide). However, 15 sets of samples were ineligible for faecal egg count reduction testing due to either too low an egg count or insufficient faecal volume. Treatment efficacy below 95%, indicating significant resistance, was detected in 81% (n=24) of flocks tested for benzimidazole resistance; in 14% (n=1) of flocks tested for levamisole resistance; and in 50% (n=7) and 62% (n=13) of flocks tested for avermectin and milbemycin resistance, respectively. Monepantel resistance was absent in all (n=3) flocks tested. Combination products (broad spectrum nematocide plus flukicide) containing levamisole were entirely effective, while treatment efficacy below 95% was detected in 60% (n=3) of flocks where the nematocide in the combination product was a benzimidazole. Where parasite identification based on coproculture was completed, Trichostrongylus was the dominant genus detected in all cases post-treatment, indicating the occurrence of anthelmintic-resistant Trichostrongylus spp. populations. Benzimidazole efficacy was highest in treating Trichostrongylus spp. (51%) and lowest when treating Teladorsagia spp. Levamisole was 100% effective in treating Cooperia, but ineffective (0%) in treating Trichostrongylus spp. Avermectin efficacy was highest when treating Haemonchus contortus (100%) and Teladorsagia spp. (73%), with a marginally lower efficacy against Trichostrongylus spp. (71%). Moxidectin efficacy was 33% against Trichostrongylus spp., 68% against Teladorsagia spp., 97% against Cooperia spp. and 100% against Haemonchus contortus infections.
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Affiliation(s)
- C McMahon
- Parasite Therapeutics Research Group, School of Biological Sciences, Medical Biology Centre, The Queen's University of Belfast, 97 Lisburn Road, Belfast, BT9 7BL, United Kingdom
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24
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The efficacy of a combined oral formulation of derquantel–abamectin against anthelmintic resistant gastro-intestinal nematodes of sheep in the UK. Vet Parasitol 2012; 189:308-16. [DOI: 10.1016/j.vetpar.2012.04.008] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2012] [Revised: 04/03/2012] [Accepted: 04/04/2012] [Indexed: 11/23/2022]
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26
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Sargison ND, Bartram DJ, Wilson DJ. Use of a long acting injectable formulation of moxidectin to control the periparturient rise in faecal Teladorsagia circumcincta egg output of ewes. Vet Parasitol 2012; 189:274-83. [PMID: 22647461 DOI: 10.1016/j.vetpar.2012.04.020] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2011] [Revised: 04/11/2012] [Accepted: 04/17/2012] [Indexed: 11/24/2022]
Abstract
A field study was conducted in a sheep flock in the south east of Scotland with a history of ivermectin resistance in Teladorsagia circumcincta. The objective of the study was to compare the effects of single anthelmintic treatments in ewes before turn-out onto pasture that was contaminated with a moderate level of overwintered, ivermectin resistant, T. circumcincta infective larvae. The ewes were treated according to label directions with either a long acting injectable formulation of moxidectin (1mg/kg; affording up to 14 weeks persistent action against macrocyclic lactone (ML)-susceptible T. circumcincta) or an oral formulation of moxidectin (0.2mg/kg; affording up to 5 weeks persistent action against ML-susceptible T. circumcincta). The lambs were enrolled in the normal management of the farm, and received a total of three oral ivermectin treatments during the 16 week study. The efficacy of both treatment strategies in controlling the periparturient rise in faecal nematode worm egg counts and subsequent pasture contamination was assessed from the faecal worm egg counts of the ewes and their lambs between lambing and weaning. Ewes that were treated with the oral formulation of moxidectin shed approximately 3.5 times more T. circumcincta eggs between lambing and weaning than ewes that were treated with the long acting formulation of moxidectin. This difference was reflected in the faecal worm egg counts of the lambs that were grazed alongside the different treatment groups of ewes. The results of the current study demonstrate persistent efficacy of the long acting formulation of moxidectin against an ivermectin resistant T. circumcincta population. The decreased pasture contamination after treatment could lead to improved lamb growth and a need for fewer anthelmintic treatments, thus potentially reducing one possible selection pressure for anthelmintic resistance. However, treatment with the long acting formulation of moxidectin would give rise to fewer susceptible nematodes being present in refugia, which could increase another possible selection pressure for anthelmintic resistance, depending on the subsequent grazing management of that pasture. The rationale for use of a persistent anthelmintic drug to control the periparturient rise in faecal ML-resistant T. circumcincta egg output of the ewes is discussed and potential differences in selection for macrocyclic lactone anthelmintic resistance using the different formulations of moxidectin are acknowledged.
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Affiliation(s)
- N D Sargison
- University of Edinburgh, Royal (Dick) School of Veterinary Studies, Farm Animal Practice, Easter Bush Veterinary Centre, Roslin, Midlothian EH25 9RG, United Kingdom.
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Abstract
Intensive use of anthelmintics to control gastrointestinal nematodes selects for anthelmintic resistance, which has become an important issue in many European countries. Presence of nematode strains resistant to benzimidazoles, imidazothiazoles and/or macrocyclic lactones has been repeatedly reported, particularly for the three most important genera, Haemonchus, Teladorsagia and Trichostrongylus. Additionally, multiple drug-resistant populations of these parasites have also been detected. Examples are given for the situation in European countries with differing climatic conditions and management systems of small ruminants. The widespread emergence of multi-resistant nematodes proves that the past intensive suppressive chemical control strategies may not be a successful approach any longer. Experience from the up to now development of anthelmintic resistance suggests that modern control schemes should not rely on sole use of anthelmintics, but employ other, more complex and sustainable recipes, combing chemical, environmental and immunological control.
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Affiliation(s)
- E Papadopoulos
- Laboratory of Parasitology and Parasitic Diseases, Faculty of Veterinary Medicine, Aristotle University of Thessaloniki, 54124 Thessaloniki, Greece.
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30
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Halliday AM, Smith WD. Attempts to immunize sheep against Teladorsagia circumcincta using fourth-stage larval extracts. Parasite Immunol 2012; 33:554-60. [PMID: 21793859 DOI: 10.1111/j.1365-3024.2011.01323.x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
A ConcanavilinA (ConA)-binding fraction of a detergent-soluble membrane extract from Teladorsagia circumcincta (formerly Ostertagia circumcincta) fourth-stage larvae was isolated, and two vaccine trials were conducted with this preparation in groups of 7 worm-free sheep. All groups were challenged with a total of 5000 T. circumcincta larvae from 1 week after the final immunization and protection assessed by comparing the egg and worm counts, and length of developing worms, of the immunized groups with their respective controls. Immunization with the ConA-binding antigen induced high-titre serum antibody responses in both trials. However, no significant reduction in either egg count or worm burdens was observed in the vaccinated groups in either trial. It was concluded that detergent-soluble, ConA-binding extracts prepared from T. circumcincta fourth-stage larvae did not contain significantly protective antigens, despite the fact that an extract prepared in a similar manner from Ostertagia ostertagi had previously significantly protected calves against homologous challenge.
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Affiliation(s)
- A M Halliday
- Moredun Research Institute, Pentlands Science Park, Bush Loan, Penicuik, Midlothian, UK.
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31
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Little PR, Hodge A, Maeder SJ, Wirtherle NC, Nicholas DR, Cox GG, Conder GA. Efficacy of a combined oral formulation of derquantel–abamectin against the adult and larval stages of nematodes in sheep, including anthelmintic-resistant strains. Vet Parasitol 2011; 181:180-93. [DOI: 10.1016/j.vetpar.2011.05.008] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2009] [Revised: 04/21/2011] [Accepted: 05/06/2011] [Indexed: 10/18/2022]
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32
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Dicker AJ, Nisbet AJ, Skuce PJ. Gene expression changes in a P-glycoprotein (Tci-pgp-9) putatively associated with ivermectin resistance in Teladorsagia circumcincta. Int J Parasitol 2011; 41:935-42. [PMID: 21683705 DOI: 10.1016/j.ijpara.2011.03.015] [Citation(s) in RCA: 68] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2011] [Revised: 03/01/2011] [Accepted: 03/04/2011] [Indexed: 11/17/2022]
Abstract
Anthelmintic resistance in parasitic nematodes of small ruminants is widespread and, in some parts of the world, threatens the sustainability of sheep production. The genetic changes underlying resistance to anthelmintics, particularly ivermectin (IVM), remain to be determined. The majority of studies to date have investigated target site mutations; relatively little attention has been paid to the role of changes in gene expression. In this study, we investigated the expression of putative drug transporter molecules, P-glycoproteins (Pgps), in Teladorsagia circumcincta, the predominant parasitic nematode species of sheep in the UK and the major anthelmintic resistant species. Utilising a degenerate PCR approach, 11 partial Pgp sequences were identified. Constitutive differences in gene expression between an IVM-susceptible (MTci2) and a multidrug-resistant (MTci5) isolate were determined for 10 of the Pgps using the ΔΔCt TaqMan® real-time PCR method. Gene expression differences were particularly marked in one of these genes, namely Tci-pgp-9. In the MTci5 isolate, statistically significant increases in Tci-pgp-9 expression, at the mRNA level, were observed across all life-cycle stages and most notably in eggs (55-fold increase). Comparison of the partial Tci-pgp-9 nucleotide sequences from MTci2 and MTci5 also identified high levels of polymorphism. This work has shown that constitutively increased expression in Tci-pgp-9, coupled with increased sequence polymorphism, could play a role in allowing multidrug-resistant T. circumcincta to survive IVM exposure. The genetic changes underpinning these gene expression changes remain to be elucidated and need to be investigated in other isolates. These changes could form the basis of an IVM resistance marker to monitor the spread of resistance and to evaluate management practices aimed at delaying its spread.
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Affiliation(s)
- Alison J Dicker
- Moredun Research Institute, Pentlands Science Park, Bush Loan, Penicuik, Midlothian, Scotland, United Kingdom
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Allison K, Taylor NM, Wilsmore AJ, Garforth C. Equine anthelmintics: survey of the patterns of use, beliefs and attitudes among horse owners in the UK. Vet Rec 2011; 168:483. [PMID: 21502196 DOI: 10.1136/vr.d731] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Abstract
An online survey was conducted to establish horse owners' beliefs, attitudes and practices relating to the use of anthelmintic drugs. Out of a total of 574 respondents, 89 per cent described themselves as 'leisure riders', most of whom took part in a variety of activities including eventing, show jumping, dressage, hunter trials, hunting, driving, endurance and showing. Overall, respondents were generally aware and concerned about the issue of anthelmintic resistance. Less than 60 per cent of all respondents were comfortable with their existing anthelmintic programme, and 25 per cent would like to reduce the use of anthelmintics in their horses. Of all the respondents, 47 per cent used livery, and 49 per cent of those reported that the livery imposed a common anthelmintic programme for horses kept on the premises; 45 per cent of these respondents were not entirely happy with the livery yard's programme. Less than 50 per cent of all respondents included 'veterinary surgeon' among their sources of advice on worming.
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Affiliation(s)
- K Allison
- Veterinary Epidemiology and Economics Research Unit, University of Reading, Earley Gate, PO Box 237, Reading, Berkshire RG6 6AR
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Jones MD, Hunter RP, Dobson DP, Reymond N, Strehlau GA, Kubacki P, Tranchard ESN, Walters ME. European field study of the efficacy and safety of the novel anthelmintic monepantel in sheep. Vet Rec 2011; 167:610-3. [PMID: 21257441 DOI: 10.1136/vr.c4477] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Abstract
During 2007, a large-scale controlled, multicentre, blinded and randomised field study was conducted in Scotland, England and France to assess the efficacy and safety of monepantel, the first molecule to be developed from the recently discovered amino-acetonitrile derivatives class of anthelmintics, in sheep. Monepantel was administered orally, at a minimum dose of 2.5 mg/kg bodyweight, for the control of gastrointestinal nematodes in sheep maintained at pasture in a range of commercial production systems. Efficacy was measured by faecal egg count (FEC) reduction tests seven days after treatment and was demonstrated to be over 98 per cent against mixed-genus infections. The reduction in FEC of monepantel-treated sheep was statistically significantly greater than in untreated control sheep (P<0.0001). The efficacy of monepantel against mixed-genus natural field infections of the major gastrointestinal nematodes was in agreement with similar studies conducted in Australia and New Zealand. There were no treatment-related adverse events during the study, which included the use of a range of concomitant treatments.
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Affiliation(s)
- M D Jones
- Novartis Animal Health, Frimley Business Park, Frimley, Camberley, Surrey GU16 7SR.
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Sargison ND. Pharmaceutical Control of Endoparasitic Helminth Infections in Sheep. Vet Clin North Am Food Anim Pract 2011; 27:139-156. [DOI: 10.1016/j.cvfa.2010.10.014] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022] Open
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Differences in efficacy of monepantel, derquantel and abamectin against multi-resistant nematodes of sheep. Parasitol Res 2010; 109:19-23. [PMID: 21161271 PMCID: PMC3118001 DOI: 10.1007/s00436-010-2216-0] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2010] [Accepted: 12/02/2010] [Indexed: 10/28/2022]
Abstract
Drug resistance has become a global phenomenon in gastrointestinal nematodes of sheep, particularly resistance to macrocyclic lactones. New anthelmintics are urgently needed for both the control of infections with multi-resistant nematodes in areas where classical anthelmintics are no longer effective, and the prevention of the spread of resistance in areas where the problem is not as severe. Recently, two new active ingredients became commercially available for the treatment of nematode infections in sheep, monepantel (Zolvix®) and derquantel, the latter used only in a formulated combination with the macrocyclic lactone, abamectin (Startect®). In order to assess the potential of the new actives for the control and prevention of spread of anthelmintic resistance, two characterized multi-resistant field isolates from Australia were used in a GLP (good laboratory practice) conducted efficacy study in sheep. Eight infected sheep in each group were treated orally according to the product labels with 2.5 mg/kg body weight monepantel, 0.2 mg/kg abamectin, or with the combination of 2.0 mg/kg derquantel and 0.2 mg/kg abamectin. The results demonstrate that monepantel was fully effective against multi-resistant species, Trichostrongylus colubriformis and Haemonchus contortus (99.9%). In contrast, the combination of derquantel and abamectin was effective against T. colubriformis (99.9%), but was not effective against larval stages of the barber's pole worm H. contortus (18.3%).
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Sargison ND, Wilson DJ, Penny CD, Bartley DJ. Unexpected production loss caused by helminth parasites in weaned beef calves. Vet Rec 2010; 167:752-4. [DOI: 10.1136/vr.c5428] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Affiliation(s)
- N. D. Sargison
- Royal (Dick) School of Veterinary Studies; University of Edinburgh, Large Animal Practice; Easter Bush Veterinary Centre; Roslin Midlothian EH25 9RG
| | - D. J. Wilson
- Royal (Dick) School of Veterinary Studies; University of Edinburgh, Large Animal Practice; Easter Bush Veterinary Centre; Roslin Midlothian EH25 9RG
| | - C. D. Penny
- Royal (Dick) School of Veterinary Studies; University of Edinburgh, Large Animal Practice; Easter Bush Veterinary Centre; Roslin Midlothian EH25 9RG
| | - D. J. Bartley
- Moredun Research Institute; Pentlands Science Park, Bush Loan Penicuik Midlothian EH26 0PZ
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Sargison ND, Scott PR, Wilson DJ, Macrae AI, Penny CD. Teladorsagia circumcincta
resistance to moxidectin and multiple anthelmintic groups in ewes following use of the persistent drug before lambing. Vet Rec 2010; 167:523-7. [DOI: 10.1136/vr.c4478] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Affiliation(s)
- N. D. Sargison
- Large Animal Practice; Royal (Dick) School of Veterinary Studies; Easter Bush Veterinary Centre; University of Edinburgh; Roslin Midlothian EH25 9RG
| | - P. R. Scott
- Large Animal Practice; Royal (Dick) School of Veterinary Studies; Easter Bush Veterinary Centre; University of Edinburgh; Roslin Midlothian EH25 9RG
| | - D. J. Wilson
- Large Animal Practice; Royal (Dick) School of Veterinary Studies; Easter Bush Veterinary Centre; University of Edinburgh; Roslin Midlothian EH25 9RG
| | - A. I. Macrae
- Large Animal Practice; Royal (Dick) School of Veterinary Studies; Easter Bush Veterinary Centre; University of Edinburgh; Roslin Midlothian EH25 9RG
| | - C. D. Penny
- Large Animal Practice; Royal (Dick) School of Veterinary Studies; Easter Bush Veterinary Centre; University of Edinburgh; Roslin Midlothian EH25 9RG
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Nisbet AJ, Bell NEV, McNeilly TN, Knox DP, Maizels RM, Meikle LI, Wildblood LA, Matthews JB. A macrophage migration inhibitory factor-like tautomerase from Teladorsagia circumcincta (Nematoda: Strongylida). Parasite Immunol 2010; 32:503-11. [PMID: 20591121 DOI: 10.1111/j.1365-3024.2010.01215.x] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
A macrophage migration inhibitory factor (MIF)-like molecule, Tci-MIF-1, was isolated from Teladorsagia circumcincta and subjected to detailed characterization. A cDNA representing Tci-mif-1 was isolated following its identification in third-stage larvae (L3)-enriched cDNA population. Sequencing of the cDNA indicated a 348-bp open reading frame (ORF) with the closest orthologue being a MIF derived from the human hookworm Ancylostoma ceylanicum. Messenger RNA (mRNA) representing the Tci-MIF-1 transcript was detected in eggs, L3 and adult stages of T. circumcincta. The transcript was also present, but to a lesser extent in fourth-stage larvae (L4). Detection of Tci-MIF-1 protein in T. circumcincta developmental stages reflected the transcript levels identified by reverse transcriptase-PCR. Using immunohistochemistry, the Tci-MIF-1 protein was shown to have a diffuse distribution in L3 tissue, and in L4 and adult stages, the protein was localized to the nematode gut. A recombinant version of Tci-MIF-1 was produced, and enzymic assays indicated that this recombinant protein and a somatic extract of L3 possessed dopachrome tautomerase activity as has been observed previously in other MIF-like molecules. Neither native, purified Tci-MIF nor recombinant Tci-MIF-1 dramatically influenced the in vitro migration of sheep monocytes.
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Affiliation(s)
- A J Nisbet
- Moredun Research Institute, Pentlands Science Park, Bush Loan, Penicuik, Scotland, UK.
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40
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Dicker AJ, Nath M, Yaga R, Nisbet AJ, Lainson FA, Gilleard JS, Skuce PJ. Teladorsagia circumcincta: the transcriptomic response of a multi-drug-resistant isolate to ivermectin exposure in vitro. Exp Parasitol 2010; 127:351-6. [PMID: 20816955 DOI: 10.1016/j.exppara.2010.08.019] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2010] [Revised: 08/24/2010] [Accepted: 08/26/2010] [Indexed: 11/30/2022]
Abstract
The emergence and spread of anthelmintic resistance in parasitic nematodes is a serious threat to the sustainability of the livestock industry. Resistance has a genetic component but the underlying mechanisms and the means by which resistant parasites survive anthelmintic treatment are still poorly understood. Differential gene expression may be implicated, especially in multi-drug resistant parasites. In this study, we investigated the transcriptomic response of a triple drug-resistant isolate of Teladorsagia circumcincta to ivermectin exposure in vitro, using Roche 454 sequencing. The study generated ∼100,000 new EST sequences, ∼50,000 each from the ivermectin-exposed and -unexposed pools of parasites. Bioinformatic analysis of the expression profiles revealed statistically significant differences in the mean expression levels of four KEGG orthologous groups, namely 'translation', 'amino acid metabolism', 'carbohydrate metabolism' and 'xenobiotic degradation and metabolism'. Notably, candidate resistance genes such as p-glycoproteins and cytochrome P450s were poorly represented in both datasets. Clusters of sequences, containing both exposed and unexposed ESTs, also revealed statistically significant differences. Four clusters were identified as cytochrome c oxidase subunits, two of these clusters had a statistically significant increase in the number of exposed ESTs compared to unexposed ESTs. Four clusters were identified as vitellogenin; three of these clusters had a statistically significant decrease in number of exposed ESTs compared to unexposed ESTs.
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Affiliation(s)
- Alison J Dicker
- Moredun Research Institute, Pentlands Science Park, Bush Loan, Penicuik, Midlothian, Scotland, UK
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Little PR, Hodges A, Watson TG, Seed JA, Maeder SJ. Field efficacy and safety of an oral formulation of the novel combination anthelmintic, derquantel-abamectin, in sheep in New Zealand. N Z Vet J 2010; 58:121-9. [PMID: 20514085 PMCID: PMC3082775 DOI: 10.1080/00480169.2010.67513] [Citation(s) in RCA: 67] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/02/2022]
Abstract
AIM: To evaluate the efficacy and safety of the novel anthelmintic combination, derquantel-abamectin, against gastrointestinal nematode populations in sheep, under field-use conditions. METHODS: Controlled faecal egg count reduction tests (FECRT) were conducted in New Zealand in 14 trials, covering a range of geographic locations, farming enterprises, breeds, nematode populations, and anthelmintic-resistance profiles. Enrolled animals were naturally infected with mixed populations of gastrointestinal nematodes. All trials included a group treated with derquantel-abamectin, and a negative control group. Nine trials included additional groups each treated with a single- or dual-active oral reference anthelmintic, selected from albendazole, levamisole, albendazole-levamisole, ivermectin, abamectin and moxidectin. A total of 838 animals were enrolled across all trials, and were randomly allocated to treatment groups within blocks defined by faecal nematode egg counts (FEC) pre-treatment. On Day 0 derquantel-abamectin was administered orally at 1 ml/5 kg bodyweight (2 mg/kg derquantel, 0.2 mg/ kg abamectin), and each reference anthelmintic was given at the recommended label dose. Faecal samples were collected on Day 14 (± 1 day), to determine the percentage reduction in mean FEC for each anthelmintic tested. Larval differentiation was also performed post-treatment, to estimate efficacy at the genus level. Animals were weighed on or before Day 0, and on Day 14 (± 1 day) in 13 trials. RESULTS: The efficacy of derquantel-abamectin against mixed strongyle populations was ≥99.2%, based on the percentage reduction in geometric mean FEC. Nematodirus sp. was present in six trials at a level sufficient for efficacy calculations to be conducted; in all cases, the efficacy of derquantel-abamectin was 100%. In those trials where the efficacy of at least one reference anthelmintic was <95% against strongyles and/or Nematodirus sp., derquantel-abamectin was 100% effective. In five trials, the mean gain in bodyweight was significantly greater in the derquantel-abamectin group than the negative controls. CONCLUSIONS AND CLINICAL RELEVANCE: When administered orally at 1 ml/5 kg bodyweight, derquantel-abamectin is highly effective for the treatment of gastrointestinal nematodes in sheep, including populations of strongyles and Nematodirus sp. with resistance to one or more single- or dual-active anthelmintics. Derquantel-abamectin presents sheep producers with a unique opportunity to introduce a new class of anthelmintic to their nematode control programmes, with the added benefits offered by a combination anthelmintic.
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Affiliation(s)
- P R Little
- Veterinary Medicine Research & Development, Pfizer Animal Health, 45 Poplar Road, Parkville 3052, Australia.
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Rufener L, Baur R, Kaminsky R, Mäser P, Sigel E. Monepantel allosterically activates DEG-3/DES-2 channels of the gastrointestinal nematode Haemonchus contortus. Mol Pharmacol 2010; 78:895-902. [PMID: 20679419 DOI: 10.1124/mol.110.066498] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Monepantel is the first drug of a new family of anthelmintics, the amino acetonitrile derivatives (AAD), presently used to treat ruminants infected with gastrointestinal nematodes such as Haemonchus contortus. Monepantel shows an excellent tolerability in mammals and is active against multidrug-resistant parasites, indicating that its molecular target is absent or inaccessible in the host and is different from those of the classic anthelmintics. Genetic approaches with mutant nematodes have suggested acetylcholine receptors of the DEG-3 subfamily as the targets of AADs, an enigmatic clade of ligand-gated ion channels that is specific to nematodes and does not occur in mammals. Here we demonstrate direct interaction of monepantel, its major active metabolite monepantel sulfone, and other AADs with potential targets of the DEG-3 subfamily of acetylcholine receptors. H. contortus DEG-3/DES-2 receptors were functionally expressed in Xenopus laevis oocytes and were found to be preferentially activated by choline, to permeate monovalent cations, and to a smaller extent, calcium ions. Although monepantel and monepantel sulfone did not activate the channels by themselves, they substantially enhanced the late currents after activation of the channels with choline, indicating that these AADs are type II positive allosteric modulators of H. contortus DEG-3/DES-2 channels. It is noteworthy that the R-enantiomer of monepantel, which is inactive as an anthelmintic, inhibited the late currents after stimulation of H. contortus DEG-3/DES-2 receptors with choline. In summary, we present the first direct evidence for interaction of AADs with DEG-3-type acetylcholine receptors and discuss these findings in the context of anthelmintic action of AADs.
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Affiliation(s)
- Lucien Rufener
- Institute of Cell Biology, University of Bern, Bühlstrasse 28, CH-3012 Bern, Switzerland
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43
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Sargison ND, Jackson F, Wilson DJ, Bartley DJ, Penny CD, Gilleard JS. Characterisation of milbemycin-, avermectin-, imidazothiazole- and benzimidazole-resistant Teladorsagia circumcincta
from a sheep flock. Vet Rec 2010; 166:681-6. [DOI: 10.1136/vr.b4853] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Affiliation(s)
- N. D. Sargison
- Large Animal Practice; Royal (Dick) School of Veterinary Studies; University of Edinburgh; Easter Bush Veterinary Centre; Roslin Midlothian EH25 9RG
| | - F. Jackson
- Department of Parasitology; Moredun Research Institute; Pentlands Science Park, Bush Loan Penicuik Midlothian EH26 0PZ
| | - D. J. Wilson
- Large Animal Practice; Royal (Dick) School of Veterinary Studies; University of Edinburgh; Easter Bush Veterinary Centre; Roslin Midlothian EH25 9RG
| | - D. J. Bartley
- Department of Parasitology; Moredun Research Institute; Pentlands Science Park, Bush Loan Penicuik Midlothian EH26 0PZ
| | - C. D. Penny
- Large Animal Practice; Royal (Dick) School of Veterinary Studies; University of Edinburgh; Easter Bush Veterinary Centre; Roslin Midlothian EH25 9RG
| | - J. S. Gilleard
- Department of Comparative Biology and Experimental Medicine; Faculty of Veterinary Medicine; University of Calgary; 3330 Hospital Drive NW Calgary Alberta Canada
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44
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Mitchell ESE, Hunt KR, Wood R, McLean B. Anthelmintic resistance on sheep farms in Wales. Vet Rec 2010; 166:650-2. [DOI: 10.1136/vr.b4840] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Affiliation(s)
- E. S. E. Mitchell
- Veterinary Laboratories Agency (VLA) - Carmarthen; Job's Well Road, Johnstown Carmarthen SA31 3EZ
| | - K. R. Hunt
- VLA - Weybridge; New Haw Addlestone Surrey KT15 3NB
| | - R. Wood
- VLA - Aberystwyth, Y Buarth; Aberystwyth Ceredigion SY23 1ND
| | - B. McLean
- ADAS Wales; Pwllperian, Cwmystwyth Aberystwyth Ceredigion SY23 4AB
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45
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Morgan ER, Coles GC. Nematode control practices on sheep farms following an information campaign aiming to delay anthelmintic resistance. Vet Rec 2010; 166:301-3. [DOI: 10.1136/vr.b4772] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Affiliation(s)
- E. R. Morgan
- School of Clinical Veterinary Science; University of Bristol; Langford House Langford, Bristol BS40 5DU
| | - G. C. Coles
- School of Clinical Veterinary Science; University of Bristol; Langford House Langford, Bristol BS40 5DU
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46
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Climate change and infectious disease: helminthological challenges to farmed ruminants in temperate regions. Animal 2010; 4:377-92. [DOI: 10.1017/s1751731109990991] [Citation(s) in RCA: 162] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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Abstract
Population medicine is an important component of veterinary care in livestock (farm animals) and companion animals (pets). This chapter covers some of the chemotherapeutic approaches undertaken at population level to control infectious diseases in domestic animals. Optimisation of health, productivity and welfare in livestock commonly entails implementation of whole-herd or whole-flock strategies to effectively counter the negative impact of infectious diseases. Gastro-intestinal and liver parasites of grazing cattle and sheep are endemic in most parts of the world and can result in significant production losses. Strategically timed anthelmintic treatments are instituted with the double objective of reducing worm burdens in infected animals and ensuring reduction of pasture contamination with infective larvae. Mastitis is another major endemic problem, particularly in cattle, which causes significant economic losses to dairy farmers globally. As a painful inflammatory condition of the cow's udder, clinical mastitis also raises animal welfare concerns. Prevention of clinical mastitis requires rigorous post-milking hygiene, identification and culling of chronically infected cows, attention to the cow's environment and therapeutic management of udder health during the dry period. A third condition that can cause high levels of morbidity and mortality is bacterial respiratory disease. Pneumonia in young livestock is often exacerbated by stressful transportation and co-mingling of animals from different herds. The welfare consequences and production losses can be significant. Antimicrobial treatment of pneumonic animals and, when appropriate, of in-contact animals living in the same air-space is an integral part of whole-herd respiratory disease management. The role of the veterinary profession is to also ensure that principles of population medicine are understood and adhered to by pet owners. The increase in pet ownership and the importance of the human-animal bond in modern developed societies give rise to zoonotic risks, which require vigilance and intervention. Regular internal parasite control in dogs and cats, particularly in endemic areas, contributes to animal welfare and minimises public health hazards.
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Affiliation(s)
- Hafid Benchaoui
- Novartis Animal Health Inc., Schwarzwaldallee 215, WRO-1032.2.44, CH-4002, Basel, Switzerland.
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49
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Taylor M, Learmount J, Lunn E, Morgan C, Craig B. Multiple resistance to anthelmintics in sheep nematodes and comparison of methods used for their detection. Small Rumin Res 2009. [DOI: 10.1016/j.smallrumres.2009.09.020] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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50
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Stafford K, Morgan E, Coles G. Weight-based targeted selective treatment of gastrointestinal nematodes in a commercial sheep flock. Vet Parasitol 2009; 164:59-65. [DOI: 10.1016/j.vetpar.2009.04.009] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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