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Poley JD, Braden LM, Messmer AM, Igboeli OO, Whyte SK, Macdonald A, Rodriguez J, Gameiro M, Rufener L, Bouvier J, Wadowska DW, Koop BF, Hosking BC, Fast MD. High level efficacy of lufenuron against sea lice (Lepeophtheirus salmonis) linked to rapid impact on moulting processes. Int J Parasitol Drugs Drug Resist 2018; 8:174-188. [PMID: 29627513 PMCID: PMC6039351 DOI: 10.1016/j.ijpddr.2018.02.007] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2017] [Revised: 02/26/2018] [Accepted: 02/28/2018] [Indexed: 11/29/2022]
Abstract
Drug resistance in the salmon louse Lepeophtheirus salmonis is a global issue for Atlantic salmon aquaculture. Multiple resistance has been described across most available compound classes with the exception of the benzoylureas. To target this gap in effective management of L. salmonis and other species of sea lice (e.g. Caligus spp.), Elanco Animal Health is developing an in-feed treatment containing lufenuron (a benzoylurea) to be administered prior to seawater transfer of salmon smolts and to provide long-term protection of salmon against sea lice infestations. Benzoylureas disrupt chitin synthesis, formation, and deposition during all moulting events. However, the mechanism(s) of action are not yet fully understood and most research completed to date has focused on insects. We exposed the first parasitic stage of L. salmonis to 700 ppb lufenuron for three hours and observed over 90% reduction in survival to the chalimus II life stage on the host, as compared to vehicle controls. This agrees with a follow up in vivo administration study on the host, which showed >95% reduction by the chalimus I stage. Transcriptomic responses of salmon lice exposed to lufenuron included genes related to moulting, epithelial differentiation, solute transport, and general developmental processes. Global metabolite profiles also suggest that membrane stability and fluidity is impacted in treated lice. These molecular signals are likely the underpinnings of an abnormal moulting process and cuticle formation observed ultrastructurally using transmission electron microscopy. Treated nauplii-staged lice exhibited multiple abnormalities in the integument, suggesting that the coordinated assembly of the epi- and procuticle is impaired. In all cases, treatment with lufenuron had rapid impacts on L. salmonis development. We describe multiple experiments to characterize the efficacy of lufenuron on eggs, larvae, and parasitic stages of L. salmonis, and provide the most comprehensive assessment of the physiological responses of a marine arthropod to a benzoylurea chemical.
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Affiliation(s)
- Jordan D Poley
- Hoplite Lab, Department of Pathology & Microbiology, Atlantic Veterinary College, University of Prince Edward Island, 550 University Ave, Charlottetown PE, C1A 4P3, Canada.
| | - Laura M Braden
- Hoplite Lab, Department of Pathology & Microbiology, Atlantic Veterinary College, University of Prince Edward Island, 550 University Ave, Charlottetown PE, C1A 4P3, Canada.
| | - Amber M Messmer
- Centre for Biomedical Research, Department of Biology, University of Victoria, Victoria BC, V8W 3N5, Canada.
| | - Okechukwu O Igboeli
- Hoplite Lab, Department of Pathology & Microbiology, Atlantic Veterinary College, University of Prince Edward Island, 550 University Ave, Charlottetown PE, C1A 4P3, Canada.
| | - Shona K Whyte
- Hoplite Lab, Department of Pathology & Microbiology, Atlantic Veterinary College, University of Prince Edward Island, 550 University Ave, Charlottetown PE, C1A 4P3, Canada.
| | - Alicia Macdonald
- Elanco Canada Limited, 150 Research Lane, Guelph, Ontario N1G 4T2, Canada.
| | - Jose Rodriguez
- Elanco Canada Limited, 150 Research Lane, Guelph, Ontario N1G 4T2, Canada.
| | - Marta Gameiro
- Elanco Canada Limited, 150 Research Lane, Guelph, Ontario N1G 4T2, Canada.
| | - Lucien Rufener
- Elanco Centre de Recherche Santé Animale SA, CH-1566 St.-Aubin, Switzerland; INVENesis LLC, Chemin de Belleroche 14, 2000 Neuchâtel, Switzerland.
| | - Jacques Bouvier
- Elanco Centre de Recherche Santé Animale SA, CH-1566 St.-Aubin, Switzerland; INVENesis LLC, Chemin de Belleroche 14, 2000 Neuchâtel, Switzerland.
| | - Dorota W Wadowska
- Electron Microscopy Laboratory, Atlantic Veterinary College, University of Prince Edward Island, 550 University Ave, Charlottetown, PEI, C1A 4P3, Canada.
| | - Ben F Koop
- Centre for Biomedical Research, Department of Biology, University of Victoria, Victoria BC, V8W 3N5, Canada.
| | - Barry C Hosking
- Elanco Canada Limited, 150 Research Lane, Guelph, Ontario N1G 4T2, Canada.
| | - Mark D Fast
- Hoplite Lab, Department of Pathology & Microbiology, Atlantic Veterinary College, University of Prince Edward Island, 550 University Ave, Charlottetown PE, C1A 4P3, Canada.
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Rojo-Vázquez FA, Hosking BC. A telephone survey of internal parasite control practices on sheep farms in Spain. Vet Parasitol 2012; 192:166-72. [PMID: 23218586 DOI: 10.1016/j.vetpar.2012.11.004] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2011] [Revised: 10/31/2012] [Accepted: 11/01/2012] [Indexed: 10/27/2022]
Abstract
A telephone survey of farmers was conducted to determine current internal parasite control practices on sheep farms in Spain; the farmers were interviewed by their veterinarians. Anthelmintic choice was largely on veterinary advice and dominated by benzimidazoles and macrocyclic lactones. Anthelmintic rotation was separated into: no rotation (42% of farms); annual rotation (36%); rotate within year (20%); and rotate every second year (2%). The mean annual number of treatments varied subtly by region; ewes and rams 1.6-2.1, replacement lambs 1.7-2.1. Anthelmintics are administered primarily during spring and early summer (47% of treatments), and autumn (41%). Thirty-two percent of farmers introduced sheep to their properties and more than half did not quarantine drench the arrivals.
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Affiliation(s)
- Francisco A Rojo-Vázquez
- Department of Sanidad Animal, Facultad de Veterinaria, Universidad de León and Instituto de Ganadería de Montaña, León, Spain
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Stein PA, George SD, Rolfe PF, Hosking BC. Safety and efficacy against fourth-stage gastrointestinal nematode larvae, of monepantel in 6-week old lambs. Vet Parasitol 2012; 185:339-42. [PMID: 22075043 DOI: 10.1016/j.vetpar.2011.10.020] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2011] [Revised: 10/05/2011] [Accepted: 10/13/2011] [Indexed: 12/01/2022]
Abstract
A controlled, blinded study was undertaken in 6-week old, pre-weaned lambs to demonstrate the safety and efficacy against fourth-stage gastrointestinal nematode larvae, of monepantel administered per os at 2.5mg/kg body weight. Worm burdens of 10 monepantel-treated lambs were compared to those from 10 untreated control lambs. Geometric mean derived efficacies of 100, 100, 96.4 and 99.9% were demonstrated against Haemonchus contortus, Teladorsagia spp., Cooperia curticei and Trichostrongylus colubriformis, respectively. These results, considered in the light of an earlier series of studies demonstrating the efficacy of monepantel in older animals, and an absence of any adverse events, provides strong support for the use of monepantel as a safe and effective anthelmintic in lambs from six weeks of age.
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Affiliation(s)
- P A Stein
- Novartis Animal Health Australasia Pty Limited, Yarrandoo R & D Centre, 245 Western Road, Kemps Creek, New South Wales 2178, Australia.
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George SD, George AJ, Stein PA, Rolfe PF, Hosking BC, Seewald W. The comparative efficacy of abamectin, monepantel and an abamectin/derquantel combination against fourth-stage larvae of a macrocyclic lactone-resistant Teladorsagia spp. isolate infecting sheep. Vet Parasitol 2012; 188:190-3. [PMID: 22459111 DOI: 10.1016/j.vetpar.2012.03.001] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2011] [Revised: 02/25/2012] [Accepted: 03/01/2012] [Indexed: 10/28/2022]
Abstract
Anthelmintic resistance by gastrointestinal nematodes of sheep continues to be an issue of global interest. While the recent introduction in some countries of one or two new anthelmintic classes (amino-acetonitrile derivatives [AAD] and spiroindoles [SI]) has been welcomed, it is important that there is no relaxation in parasite control and the management of drug resistance. Monepantel (an AAD) was the first new anthelmintic to be approved for use (New Zealand, 2009) and was followed a year later in the same country by a combination of derquantel (a SI) and abamectin. The present study determined the efficacy of the new anthelmintic products and abamectin against fourth-stage larvae of macrocyclic lactone-resistant Teladorsagia spp. in lambs. Efficacies were calculated by comparing post-mortem nematode burdens of treated animals with those of untreated control sheep, and were 98.5, 86.3 and 34.0% for monepantel, abamectin/derquantel and abamectin, respectively. The nematode burdens of monepantel- and abamectin/derquantel-treated sheep were significantly lower than those sheep treated with abamectin and the untreated controls. Similarly, the burden of the monepantel group was significantly lower than that of the abamectin/derquantel group. These findings provide an opportunity to reinforce the recommendation that farmers and animal health advisors need to know the resistance status of nematode populations on subject farms to ensure effective control programs are designed and implemented. Such control programs should include an appropriate choice of anthelmintic(s), monitoring parasite burdens for correct timing of treatments, and pasture management to reduce larval challenge balanced with the maintenance of drug-susceptible populations in refugia.
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Affiliation(s)
- S D George
- Novartis Animal Health Australasia Pty Limited, Yarrandoo R&D Centre, 245 Western Road, Kemps Creek, NSW 2178, Australia.
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Dobson RJ, Barnes EH, Tyrrell KL, Hosking BC, Larsen JWA, Besier RB, Love S, Rolfe PF, Bailey JN. A multi-species model to assess the effect of refugia on worm control and anthelmintic resistance in sheep grazing systems. Aust Vet J 2011; 89:200-8. [PMID: 21595639 DOI: 10.1111/j.1751-0813.2011.00719.x] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
OBJECTIVE Develop a computer simulation model that uses daily meteorological data and farm management practices to predict populations of Trichostrongylus colubriformis, Haemonchus contortus and Teladorsagia (Ostertagia) circumcincta and the evolution of anthelmintic resistance within a sheep flock. Use the model to explore if increased refugia, provided by leaving some adult sheep untreated, would delay development of anthelmintic resistance without compromising nematode control. PROCEDURES Compare model predictions with field observations from a breeding flock in Armidale, NSW. Simulate the impact of leaving 1-10% of adult sheep untreated in diverse sheep-grazing systems. RESULTS Predicted populations of Tr. colubriformis and T. circumcincta were less than those observed in the field, attributed to nutritional stress experienced by the sheep during drought and not accounted for by the model. Observed variation in faecal egg counts explained by the model (R(2) ) for these species was 40-50%. The H. contortus populations and R(2) were both low. Leaving some sheep untreated worked best in situations where animals were already grazing or were moved onto pastures with low populations of infective larvae. In those cases, anthelmintic resistance was delayed and nematode control was maintained when 1-4% of adult stock remained untreated. CONCLUSIONS In general, the model predicted that leaving more than 4% of adults untreated did not sufficiently delay the development of anthelmintic resistance to justify the increased production risk from such a strategy. The choice of a drug rotation strategy had an equal or larger effect on nematode control, and selection for resistance, than leaving 1-10% of adults untreated.
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Affiliation(s)
- R J Dobson
- School of Veterinary & Biomedical Sciences, Murdoch University, South Street, Murdoch, Western Australia 6150, Australia.
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Dobson RJ, Hosking BC, Besier RB, Love S, Larsen JWA, Rolfe PF, Bailey JN. Minimising the development of anthelmintic resistance, and optimising the use of the novel anthelmintic monepantel, for the sustainable control of nematode parasites in Australian sheep grazing systems. Aust Vet J 2011; 89:160-6. [PMID: 21495986 DOI: 10.1111/j.1751-0813.2011.00703.x] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
OBJECTIVE To compare the risk of different treatment scenarios on selecting for anthelmintic resistance on Australian sheep farms. DESIGN A computer simulation model predicted populations of Trichostrongylus colubriformis, Haemonchus contortus or Teladorsagia (Ostertagia) circumcincta, and the frequency of anthelmintic resistance genes. METHOD Nematode populations and the progression of drug resistance for a variety of treatment options and management practices in sheep-rearing areas of Western Australia (WA), Victoria (VIC) and New South Wales (NSW) were simulated. A scoring system was devised to measure the success of each option in delaying resistance to each anthelmintic and in controlling nematode populations. RESULTS The best option at all sites was combining the new anthelmintic (monepantel) with a triple mixture of benzimidazole, levamisole and abamectin (COM). The next best option was: in NSW, rotation at each treatment between monepantel, moxidectin and COM; in VIC, rotation at each treatment between monepantel and COM; and in WA, rotation at each treatment between monepantel (used in winter) and COM or moxidectin (used in summer-autumn). In WA, rapid selection for resistance occurred as a consequence of summer-autumn treatments; however, if a small percentage of adult stock were left untreated then this selection could be greatly reduced. Despite purposely assuming relatively high resistance to benzimidazole and levamisole, COM was still effective in controlling worms and delaying resistance. CONCLUSIONS Because of cost constraints, it may not be feasible or profitable for producers to always use the combination of all drugs. However, the second- and third-best options still considerably slowed the development of anthelmintic resistance.
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Affiliation(s)
- R J Dobson
- School of Veterinary & Biomedical Sciences, Murdoch University, Murdoch, Western Australia 6150, Australia.
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Abstract
A sample survey of anthelmintic usage and farmers; drenching policies was conducted on 614 sheep farms, in the North and South Islands, selected from among those carrying 1500 or more breeding ewes. The survey was based on information for the 1978179 and 1979/80 farming years recorded on questionnaires completed during personal interviews between Livestock Officers and the farmers concerned. Results show that there were no significant between-Island differences in mean drenching frequencies for any age class of sheep. In 1979/80, the overall New Zealand drenching frequencies were 6.3 for lambs, 1.8 for 1-2-year-olds and 1.2 for sheep older than 2 years. Of the farmers surveyed, 20% did not drench 1-2-year-old sheep and 29% did not drench sheep older than 2 years. There were also no between-Island differences in timing of drenches and alternation of drench brands. Sixty-nine per cent of the farmers followed a pre-determined drenching programme whereas 27% stated that they drenched if and when necessary. For lambs, some drenching was carried out in all months of the year hut fewer farmers drenched during the mid-winter to mid-spring period (July-October). Older stock were drenched in all months also but there was a general acceptance by farmers of the practices of pre-tupping and pre or post-lambing drenching. At the time of the survey, 48% of the farmers were using three or more brands of drench with a maximum of nine. Analysis of data relating to brands of drench used shows that whereas 39% of the farmers w,ere alternating drench families [i.e. benzimidazoles (BZ) c.f. non-benzimidazoles (NBZ)] within a single farming year, only 3% were practising a strict alternation of drench families between years. General comments by the farmers surveyed indicate a disturbing degree of misunderstanding and misconception regarding the properties and limitations of current anthelmintics. The survey also revealed a lack of appreciation of the rationale of prophylactic (;preventive;) parasite control. These aspects are discussed in relation to currently recommended control strategies and the problem of anthelmintic resistance.
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Affiliation(s)
- R V Brunsdon
- Wallaceville Animal Research Centre, Research Division, Ministry of Agriculture and Fisheries, Private Bag, Upper Hutt
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Abstract
Multiple resistance was demonstrated within the experimental milking goat herd at the Ruakura Agricultural Centre. The development of this resistance was probably exacerbated by the atypical animal management and parasite control programmes under which the dairy was managed. Resistance by Teladorsagia (Ostertagia) spp. to members of the three broad-spectrum families of anthelmintic is reported for the first time. Worm counts in a controlled slaughter trial demonstrated multiple anthelmintic resistance in a mixed population of Teladorsagia (T. circumcincta and T. trifurcata) and Trichostrongylus spp. The efficacies of oxfendazole, morantel citrate and ivermectin in reducing the Teladorsagia population were 43.8%, 75.6% and 93.1%, respectively. Ivermectin removed more than 99% of the small intestinal Trichostrongylus spp. but oxfendazole and morantel were less effective, removing 37.9% and 87.7%, respectively. Only treatment with ivermectin totally eliminated faecal nematode egg counts 8 days after treatment. The lack of agreement between faecal nematode egg depressions and worm counts in lambs given ivermectin suggests that the drug may have affected the fecundity of the surviving nematode population or the assay lacked the sensitivity required. These data suggest that the sole use of faecal egg depression would be inappropriate for accurate assessment of anthelmintic effectiveness.
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Affiliation(s)
- T G Watson
- Ruakura Agricultural Centre, Private Bag, Hamilton, New Zealand
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Hosking BC, Griffiths TM, Woodgate RG, Besier RB, Le Feuvre AS, Nilon P, Trengove C, Vanhoff KJ, Kaye-Smith BG, Seewald W. Clinical field study to evaluate the efficacy and safety of the amino-acetonitrile derivative, monepantel, compared with registered anthelmintics against gastrointestinal nematodes of sheep in Australia. Aust Vet J 2010; 87:455-62. [PMID: 19857240 DOI: 10.1111/j.1751-0813.2009.00511.x] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
OBJECTIVE To determine the efficacy of monepantel, a developmental compound from the amino-acetonitrile derivative class of anthelmintics, against field infections of gastrointestinal nematodes in sheep. PROCEDURES Comparisons of efficacy (using standard faecal worm egg count reduction tests) and safety (on the basis of visual observations) were made in a large-scale field study in Australia, between groups of sheep treated with either an oral solution of monepantel or a registered anthelmintic. The sheep were naturally infected with the major gastrointestinal nematode genera present in Australia. RESULTS The post-treatment efficacy results for monepantel were: at 7 days (+/-1 day) efficacy was >98%; at 14 days (+/-1 day) it was generally close to or >99%; and at 21 days (+/-1 day) efficacy was consistently >99%. A high proportion of the targeted nematode populations were confirmed as being resistant to one or more of the currently available anthelmintic classes. CONCLUSIONS Monepantel when used under field conditions at a minimum dose rate of 2.5 mg/kg was highly effective against mixed-genus natural field infections of the major gastrointestinal nematode genera including Haemonchus, Teladorsagia (Ostertagia), Trichostrongylus, Nematodirus, Chabertia and Oesophagostomum. This result included efficacy against some populations resistant to the currently available broad-spectrum anthelmintics. Few Cooperia spp. were present to allow confirmation of efficacy against this genus. On no occasion after treatment did any commercial anthelmintic-treated groups have significantly lower faecal egg counts than the monepantel-treated groups. Monepantel was safe for the target animals and human operators when used in a field situation.
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Affiliation(s)
- B C Hosking
- Novartis Animal Health Australasia Pty Limited, Yarrandoo R & D Centre, Kemps Creek, New South Wales 2178, Australia.
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Leathwick DM, Hosking BC. Managing anthelmintic resistance: modelling strategic use of a new anthelmintic class to slow the development of resistance to existing classes. N Z Vet J 2009; 57:203-7. [PMID: 19649013 DOI: 10.1080/00480169.2009.36902] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
AIM To test the hypothesis that a single strategic treatment with a new class of anthelmintic could slow the development of resistance to existing classes of anthelmintic. METHODS An existing model was used to simulate nematode parasite dynamics and the development of anthelmintic resistance. Variations on a five-drench preventive programme of treatments for lambs, in which either zero, the first, third or fifth treatment was substituted with a different class of drug, were compared for the time to reach treatment failure (defined as efficacy <95%). The sensitivity to variations in the death rate of adult worms, that varied from 1 to 5%, and the dominance of resistance genes were also assessed. RESULTS Replacing one of the five treatments with a different class of anthelmintic almost always slowed the development of resistance, and was never worse than using the same drug for all treatments. Further, there were large differences in the relative time to treatment failure depending on which treatment was substituted. Changing the first treatment always had the least benefit, whereas changing the fifth treatment always had the greatest. This pattern was independent of the daily death rate of adult worms, and was not influenced by the dominance of resistance under treatment. CONCLUSIONS The results indicated that strategic substitution of a single treatment with a new class of anthelmintic, at the end of a series of preventive treatments to lambs using an existing class, could slow the further development of resistance to the latter. This strategic use of a new anthelmintic class has the potential to greatly extend the life of existing anthelmintics if these are still effective.
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Affiliation(s)
- D M Leathwick
- AgResearch Grasslands, Private Bag 11008, Palmerston North 4442, New Zealand.
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Leathwick DM, Hosking BC, Bisset SA, McKay CH. Managing anthelmintic resistance: Is it feasible in New Zealand to delay the emergence of resistance to a new anthelmintic class? N Z Vet J 2009; 57:181-92. [DOI: 10.1080/00480169.2009.36900] [Citation(s) in RCA: 62] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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Abstract
Eighteen, six- to seven-month-old lambs were infected experimentally with larvae of Haemonchus contortus, Teladorsagia circumcincta, Trichostrongylus axei, Trichostrongylus colubriformis, Cooperia curticei and Nematodirus spathiger, and allocated to three equal groups. The infections were timed to ensure that fourth-stage larvae were present when groups 1 and 2 were treated orally with monepantel. Group 1 was not fed for 24 hours before the treatment, group 2 was fed two hours before the treatment and group 3 was fed at the same time as group 2 but not treated with monepantel. All the sheep had access to water. Worm burdens were determined 15 days after the treatments. Fasting or feeding had no statistically significant effects on the efficacy of the monepantel solution against the nematodes, and the period of fasting had no adverse effects.
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Affiliation(s)
- B C Hosking
- Novartis Animal Health Australasia, Yarrandoo R&D Centre, 245 Western Road, Kemps Creek, New South Wales 2178, Australia.
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Mason PC, Hosking BC, Nottingham RM, Cole DJW, Seewald W, McKay CH, Griffiths TM, Kaye-Smith BG, Chamberlain B. A large-scale clinical field study to evaluate the efficacy and safety of an oral formulation of the amino-acetonitrile derivative (AAD), monepantel, in sheep in New Zealand. N Z Vet J 2009; 57:3-9. [DOI: 10.1080/00480169.2009.36861] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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Malikides N, Helbig R, Roth DR, Alexander A, Hosking BC, Strehlau GA. Safety of an amino-acetonitrile derivative (AAD), monepantel, in weaned lambs following repeated oral administration. N Z Vet J 2009; 57:10-5. [DOI: 10.1080/00480169.2009.36862] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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Kaminsky R, Gauvry N, Schorderet Weber S, Skripsky T, Bouvier J, Wenger A, Schroeder F, Desaules Y, Hotz R, Goebel T, Hosking BC, Pautrat F, Wieland-Berghausen S, Ducray P. Identification of the amino-acetonitrile derivative monepantel (AAD 1566) as a new anthelmintic drug development candidate. Parasitol Res 2008; 103:931-9. [PMID: 18594861 PMCID: PMC2491438 DOI: 10.1007/s00436-008-1080-7] [Citation(s) in RCA: 116] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2008] [Accepted: 06/02/2008] [Indexed: 11/29/2022]
Abstract
Anthelmintic resistance has become a global phenomenon in gastro-intestinal nematodes of farm animals, including multi-drug resistance against the three major classes of anthelmintics. There is an urgent need for an anthelmintic with a new mode of action. The recently discovered amino-acetonitrile derivatives (AADs) offer a new class of synthetic chemicals with anthelmintic activity. The evaluation of AADs was pursued applying in vitro assays and efficacy and tolerability studies in rodents, sheep, and cattle. Amongst various suitable compounds, AAD 1566 eliminated many tested pathogenic nematode species, both at larval and adult stages, at a dose of 2.5 mg/kg bodyweight in sheep and 5.0 mg/kg bodyweight in cattle. The same doses were sufficient to cure animals infected with resistant or multi-drug-resistant nematode isolates. These findings, complemented by the good tolerability and low toxicity to mammals, suggest that AAD 1566, monepantel, would be a suitable anthelmintic drug development candidate.
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Affiliation(s)
- R Kaminsky
- Novartis Centre de Recherche Santé Animale, CH-1566 St. Aubin, Switzerland.
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Nottingham RM, Hosking BC, Schmid HR, Strehlau G, Junquera P. Prevention of blowfly strike on coarse and fine woolled sheep with the insect growth regulator dicyclanil. Aust Vet J 2001; 79:51-7. [PMID: 11221571 DOI: 10.1111/j.1751-0813.2001.tb10641.x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
OBJECTIVE To assess a ready-to-use formulation of dicyclanil to prevent blowfly strike on coarse and fine woolled sheep under New Zealand conditions. DESIGN Randomized clinical field trials. PROCEDURE In a first field trial, coarse wooled sheep treated with a ready-to-use, 5% dicyclanil formulation were compared with untreated control sheep for up to 21 weeks. In a second field trial, fine woolled sheep, treated with the same dicyclanil formulation, were compared with untreated sheep for up to 19 weeks. Efficacy was assessed by calculating the aggregated cumulative strike rate. RESULTS For trial 1 (coarse woolled sheep) the aggregated cumulative strike rate at the end of the trial at week 21 after treatment reached 3.9% and 19.1% for treated and untreated sheep, respectively. For the treated animals the aggregated cumulative strike rate reached the 1% and 2% benchmarks between weeks 11 and 12. For trial 2 (fine woolled sheep) the aggregated cumulative strike rate at the end of the trial at week 19 reached 0.6% and 7.5% for treated and untreated sheep, respectively. Wool length at the time of application did not substantially influence the efficacy of dicyclanil. CONCLUSION Under New Zealand field conditions, a ready-to-use 5% spray-on formulation of dicyclanil protected coarse woolled sheep for at least 12 weeks and fine woolled sheep for at least 19 weeks.
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Affiliation(s)
- R M Nottingham
- Novartis New Zealand Ltd, Private Bag 19-980, Avondale, Auckland, 1007, New Zealand
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Watson TG, Hosking BC, Leathwick DM, McKee PF. Ivermectin-moxidectin side resistance by Ostertagia species isolated from goats and passaged to sheep. Vet Rec 1996; 138:472-3. [PMID: 8735540 DOI: 10.1136/vr.138.19.472] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Affiliation(s)
- T G Watson
- Ruakura Agricultural Research Centre, Hamilton, New Zealand
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Affiliation(s)
- B C Hosking
- AgResearch, Ruakura Agricultural Research Centre, Hamilton, New Zealand
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Watson TG, Hosking BC, Hooke FG. Efficacy of doramectin against naturally acquired adult and inhibited larval infections by some nematode parasites in cattle in New Zealand. N Z Vet J 1995; 43:64-6. [PMID: 16031810 DOI: 10.1080/00480169.1995.35850] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
A study was conducted to determine the therapeutic efficacy of 1% doramectin injected subcutaneously at 200 microg/kg into cattle harbouring naturally acquired infections of inhibited Ostertagia ostertagi larvae. Sixteen yearling Friesian bulls, grazed without anthelmintic treatment throughout the autumn-winter, were selected on the basis of similar body weights and serum pepsinogen activities. After removal from pasture on day -23 they were weighed and randomly assigned to two treatment groups on the basis of this weight. On day 0, one group was given saline (1 ml/50 kg) while the second was treated with doramectin (200 microg/kg). Both treatments were given by subcutaneous injection. All stock were slaughtered 14-15 days after treatment. Moderate to high levels of adult O. ostertagi and Trichostrongylus axei and early and late 4th larval stages of O. ostertagi were recovered from saline-treated calves at necropsy. Doramectin was highly effective in eliminating all stages of O. ostertagi (99.9%; p<0.0001) and T. axei (100%; p<0.0001). No evidence of lesions were detected at the injection sites at necropsy. These results confirm that doramectin is an extremely effective broad-spectrum avermectin anthelmintic with efficacy against inhibited as well as maturing larval and adult forms of O. ostertagi.
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Affiliation(s)
- T G Watson
- AgResearch Ruakura, Private Bag 3123, Hamilton, New Zealand
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Abstract
A study was undertaken to determine the efficacy of the novel avermectin, doramectin, against experimental larval and adult infections of three species of nematode parasite important to cattle production in New Zealand. Eighteen worm-free dairy bull beef calves were randomly allocated on live weight to three similar treatment groups. Each calf was given 30,000 Ostertagia ostertagi, 20,000 Cooperia spp. and 10,000 Trichostrongylus axei infective larvae as a single dose. One group was treated with doramectin 6 days after infection while the remaining groups received saline or doramectin 27 days after infection. Given as a single subcutaneous injection behind the ear, doramectin at 200 microg/kg removed 99.9-100% of adult and larval stages of O. ostertagi, Cooperia spp. and T. axei when compared to infections established in untreated controls (p<0.001). No adverse reactions were observed following treatment in the doramectin-treated animals. No injection site lesions were found by palpation following treatment or by injection site examination at necropsy.
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Affiliation(s)
- T G Watson
- AgResearch Ruakura, Private Bag 3123, Hamilton, New Zealand
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