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The use of DNA markers to map anthelmintic resistance loci in an intraspecific cross of Haemonchus contortus. Parasitology 2009; 137:705-17. [DOI: 10.1017/s0031182009991521] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
SUMMARYThe use of DNA markers to track the development of anthelmintic resistance in parasites of livestock would allow informed choices for the management of this important problem. We describe a genetic mapping approach for the discovery of DNA markers for anthelmintic resistance in Haemonchus contortus. We crossed a multi-drug resistant field isolate of H. contortus with a well-characterized laboratory strain susceptible to 4 drug classes. The F2 were separately selected with 5 anthelmintics from 4 drug classes, producing drug-resistant populations carrying gene variants derived from both the field isolate and the laboratory strain. Individual F2 worms were analysed using amplicon length polymorphisms (ALPs). We looked for field isolate alleles over- or under-represented in F2 populations compared to the unselected F2 and/or the laboratory strain. The data we obtained suggest that marker association can be used to link neutral markers with resistance, but also that more markers and perhaps more inbred laboratory strains would make the procedure more likely to succeed.
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Conder GA, Campbell WC. Chemotherapy of nematode infections of veterinary importance, with special reference to drug resistance. ADVANCES IN PARASITOLOGY 1995; 35:1-84. [PMID: 7709851 DOI: 10.1016/s0065-308x(08)60069-x] [Citation(s) in RCA: 89] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Affiliation(s)
- G A Conder
- Upjohn Laboratories, Upjohn Company, Kalamazoo, Michigan
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Rahman WA. Survey for drug-resistant trichostrongyle nematodes in ten commercial goat farms in west Malaysia. Trop Anim Health Prod 1994; 26:235-8. [PMID: 7900221 DOI: 10.1007/bf02240391] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
The prevalence of drug-resistant parasites in goats in West Malaysia has rarely been reported. Ten commercial goat farms were surveyed for resistance to anthelminthics by measuring the reduction in faecal egg counts (FECs) after treatment with levamisole, pyrantel pamoate and fenbendazole. Resistance to fenbendazole was seen in most farms; there was no evidence of resistance to levamisole but some resistance to pyrantel pamoate was detected on one farm. The significance of the findings are discussed.
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Affiliation(s)
- W A Rahman
- School of Biological Sciences, Universiti Sains Malaysia, Penang
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Abstract
Macrocyclic lactone endectocides include two chemically distinct compounds moxidectin, a milbemycin, and ivermectin, an avermectin. The significance of the chemical differences between these compounds in relation to nematode resistance remains to be established. Reported studies indicate that moxidectin at the recommended dose rate of 0.2 mg/kg controls identified strains of nematodes, isolated from sheep and goats, with demonstrated resistance to ivermectin. This reflects the significantly greater potency of moxidectin against the 3 genera of nematodes most commonly involved in anthelmintic resistance, Haemonchus, Ostertagia and Trichostrongylus. Moxidectin, in recommended strategic treatment programmes, should reduce the risk of further development of resistance to the macrocylic lactone endectocides.
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Waller PJ, Mahon RJ, Wardhaugh KG. Regional and temporal use of avermectins for ruminants in Australia. Vet Parasitol 1993; 48:29-43. [PMID: 8346642 DOI: 10.1016/0304-4017(93)90142-a] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
The avermectin class of anthelmintics has been available for approximately 4 years (sheep) and 7 years (cattle) in Australia. They are highly efficacious against a very broad spectrum of nematode parasites and certain ectoparasites of livestock. To date there are no field reports of resistance to these compounds in either the cattle or sheep industry, despite the fact that nematode parasites of sheep show high levels of resistance to other broad spectrum anthelmintics. The avermectins have gained rapid acceptance, but their share of the anthelmintic market is less than expected, owing to several factors such as drought and recession of the rural economy. Nevertheless, it can be expected that this class of compounds will assume greater importance, particularly in the sheep industry, when greater awareness of the widespread failure of alternative broad spectrum anthelmintics, and the value of regional worm control programs become accepted by producers.
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Affiliation(s)
- P J Waller
- CSIRO Division of Animal Health, McMaster Laboratory, Glebe, N.S.W., Australia
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Love SC, Johns WH, Coverdale OR. Anthelmintic resistance in sheep nematodes in the New England region of New South Wales. Aust Vet J 1992; 69:196-7. [PMID: 1530557 DOI: 10.1111/j.1751-0813.1992.tb07523.x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Affiliation(s)
- S C Love
- Regional Veterinary Laboratory, NSW Agriculture and Fisheries, University of New England, Armidale
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Prichard RK. Anthelmintic resistance in nematodes: extent, recent understanding and future directions for control and research. Int J Parasitol 1990; 20:515-23. [PMID: 2210945 DOI: 10.1016/0020-7519(90)90199-w] [Citation(s) in RCA: 118] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Resistance has now been reported to all of the broad spectrum anthelmintic types currently available, namely to the benzimidazoles, levamisole/morantel and to ivermectin. The problem causes most concern for parasite control in sheep, but anthelmintic resistance has also been reported in nematodes of horses, goats, pigs and more recently cattle. Our understanding of the factors which select rapidly for resistance has increased and programmes of worm control which minimize selection for anthelmintic resistance are being developed and tested. One of the greatest problems encountered in attempting to reduce the selection for overt drug resistance is the need for more sensitive tests for developing resistance. In the long term, new approaches to chemotherapy and to overcoming anthelmintic resistance problems will arise from improving our understanding of the modes of action of, and mechanisms of resistance to, anthelmintics at the level of the receptor proteins and their genes.
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Affiliation(s)
- R K Prichard
- Institute of Parasitology, McGill University, Macdonald College, Ste-Anne de Bellevue, Qc Canada
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Scherrer AM, Pomroy WE, Charleston WA. A survey of anthelmintic resistance on ten goat farms in the Manawatu region in 1988. N Z Vet J 1989; 37:148-9. [PMID: 16031550 DOI: 10.1080/00480169.1989.35590] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
A survey of anthelmintic resistance on ten goat farms was carried out. The criterion for resistance was a faecal egg count reduction (FECR) of <90 percent based on arithmetic means of 11 to 19 goats per group. It was found that nine of the ten farms harboured nematodes resistant to oxfendazole when used at 5mg/kg although on two of these, the FECR's were 89.2 percent and 89.8 percent. Post treatment larval cultures indicated Haemonchus, Ostertagia and Trichostrongylus were the resistant genera involved. On none of the ten farms was resistance to oral ivermectin at 0.2mg/kg detected.
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Affiliation(s)
- A M Scherrer
- Department of Veterinary Pathology and Public Health, Massey University, Palmerston North
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Martin PJ, Anderson N, Jarrett RG. Detecting benzimidazole resistance with faecal egg count reduction tests and in vitro assays. Aust Vet J 1989; 66:236-40. [PMID: 2590136 DOI: 10.1111/j.1751-0813.1989.tb13578.x] [Citation(s) in RCA: 154] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Composite strains of Trichostrongylus colubriformis and Ostertagia spp consisting of 0, 1, 10, 25, 50, 75, 90, and 100% of known resistant strains were prepared and tested for benzimidazole resistance using faecal egg count reduction tests, in vitro egg hatch assays and tubulin binding assays. All tests detected resistance where the proportion of the resistant strain in the composite was 50% or more, whereas none of the tests unequivocally detected resistance below 25%. Egg count reduction tests were no less sensitive than the in vitro tests in detecting low levels of resistance but the egg hatch and tubulin binding assays provided a better quantitative estimate of moderate to high levels of resistance. Faecal egg count reduction therefore, provides a suitable means of detecting resistance in the field but tests, more sensitive to low levels of resistance are required. Results indicate that the use of post-treatment counts alone provides an adequate indication of anthelmintic efficiency.
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Affiliation(s)
- P J Martin
- CSIRO, Division of Animal Health, Animal Health Research Laboratory, Parkville, Victoria 3052
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BOERSEMA J, BORGSTEEDE F, EYSKER M, HENDRIKX W, JANSEN J, SMITH-BUYS C. Prevalence of benzimidazole resistance of nematodes in sheep in The Netherlands. Res Vet Sci 1987. [DOI: 10.1016/s0034-5288(18)30734-3] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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Bauer C, Merkt JC, Janke-Grimm G, Bürger HJ. Prevalence and control of benzimidazole-resistant small strongyles on German thoroughbred studs. Vet Parasitol 1986; 21:189-203. [PMID: 3529602 DOI: 10.1016/0304-4017(86)90065-8] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
The prevalence of benzimidazole-resistant small strongyles was determined in a survey, conducted on 14 thoroughbred studs, which compared the faecal egg counts of groups of horses before and after treatment with the recommended doses of cambendazole (20 mg kg-1 b.w.) or febantel (6 mg kg-1 b.w.). Benzimidazole-resistant cyathostomes were found on all farms examined. Pyrantel pamoate (19 mg kg-1 b.w.), oxibendazole (10 mg kg-1 b.w.) and ivermectin (0.2 mg kg-1 b.w.) reduced the strongyle egg counts on these studs by 97-100% at 2 weeks post-treatment. However, 6 weeks after dosing the reduction of the strongyle egg output had decreased to an average of 67.8% (8.7-97.1%) with pyrantel pamoate and 51.2% (0-95.8%) with oxibendazole, whereas ivermectin still suppressed the egg counts by 98.2% (95-100%).
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Edwards JR, Wroth R, de Chaneet GC, Besier RB, Karlsson J, Morcombe PW, Dalton-Morgan G, Roberts D. Survey of anthelmintic resistance in Western Australian sheep flocks. 1. Prevalence. Aust Vet J 1986; 63:135-8. [PMID: 3753339 DOI: 10.1111/j.1751-0813.1986.tb02950.x] [Citation(s) in RCA: 32] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Between July 1981 and December 1983, 116 randomly selected sheep farms in the south west of Western Australian were surveyed for resistance to anthelmintics. A faecal worm egg count reduction test was carried out on each farm. Anthelmintics tested were thiabendazole (44 mg/kg) and levamisole (7.5 mg/kg) given by intra-ruminal injection and comparisons were made with an untreated group on each farm. Successful tests were carried out on 84 farms and 68% of these had resistant worms present. The prevalence of thiabendazole resistant populations was for H. contortus 18%; Teladorsagia, 41% and Trichostrongylus, 48% and for levamisole resistant populations H. contortus, 10%; Teladorsagia, 41%; Trichostrongylus, 24%, and Nematodirus, 10%. Multiple resistant populations were found on 17% of farms. Although the distribution of nematode genera varied between the 400 to 750 mm and the greater than 750 mm rainfall zones there was no significant difference in the prevalence of resistance between zones. About one third of resistant populations were severely resistant (less than 60% reduction). It is likely that resistant worms were present on many farms without causing clinical disease and continued anthelmintic selection pressure will result in further development of resistance.
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Abstract
Following the failure of anthelmintic treatment to control an outbreak of trichostrongylosis in sheep, multiple resistance to levamisole and oxfendazole was confirmed in field strains of Trichostrongylus colubriformis at the CSIRO Pastoral Research Laboratory, Armidale. Resistance in Trichostrongylus spp to levamisole was also confirmed on an adjoining farm. From the results of an experiment where lambs were treated at the recommended dose rate with one or both anthelmintics, it was estimated that 32% of T. colubriformis were resistant to levamisole, 19% to oxfendazole, and 12% to both drugs. Simultaneous administration of levamisole and oxfendazole resulted in an additive anthelmintic effect. Naphthalophos (36.6 to 51.2 mg/kg) was 93% efficient against the multiple resistant strain. The similar histories of anthelmintic usage at the CSIRO Pastoral Research Laboratory and on the northern tablelands of New South Wales generally, suggest that multiple anthelmintic resistance in T. colubriformis may soon emerge as a problem on the northern tablelands.
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Dash KM. Control of helminthosis in lambs by strategic treatment with closantel and broad-spectrum anthelmintics. Aust Vet J 1986; 63:4-7. [PMID: 3954695 DOI: 10.1111/j.1751-0813.1986.tb02861.x] [Citation(s) in RCA: 50] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Treatment of ewes with broad-spectrum anthelmintic in August (pre-lambing) and early November, and of lambs in early November and early February, was effective in controlling infections with Trichostrongylus spp in lambs reared on contaminated pastures under set-stocked conditions. It was ineffective in controlling infections with Haemonchus contortus; 82% of lambs had to be withdrawn from the experiment because of severe haemonchosis. Treatment with closantel (7.5 mg/kg) at the same times was very effective against H. contortus but ineffective against Trichostrongylus spp; 25% of lambs had to be withdrawn because of severe trichostrongylosis. The same schedule using broad spectrum anthelmintic and closantel administered concurrently was effective against both parasites; no lambs had to be withdrawn and the bodyweight gain of lambs was higher than in lambs treated with broad-spectrum anthelmintic or closantel alone. The results provide a basis on which to develop a preventive anthelmintic treatment program to control haemonchosis and trichostrongylosis in sheep which will allow the current high frequency of treatment with broad-spectrum anthelmintics to be reduced. Such a program may retard selection for anthelmintic resistance in Trichostrongylus spp.
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Webb RF, Ottaway SJ. The prevalence of anthelmintic resistance in sheep nematodes on the central tablelands of New South Wales. Aust Vet J 1986; 63:13-6. [PMID: 3954686 DOI: 10.1111/j.1751-0813.1986.tb02863.x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
A survey was undertaken to assess the prevalence of anthelmintic resistance in sheep nematode populations on 40 commercial farms distributed throughout the central tablelands of New South Wales. Representatives of the 2 major groups of broad spectrum anthelmintics with different modes of action (thiabendazole and levamisole) were used at the manufacturer's recommended dose rates. Efficacy was assessed on the basis of the reduction in faecal strongyle egg counts 7 days after treatment. An efficacy of less than 90% using both anthelmintics was obtained on 4 farms. Thiabendazole had an efficacy of less than 90% on a further 21 farms and levamisole had an efficacy of less than 90% on an additional 4 farms. There was no evidence of anthelmintic resistance on 8 farms, while the remaining 3 had insignificant parasite burdens. Based on larval cultures from faeces, Ostertagia and Trichostrongylus were the most significant species in resistant populations. Haemonchus burdens were sporadic and levels of resistance relatively low. Nematodirus burdens were widespread but no evidence of resistance was detected.
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Riffkin GG, Callinan AP, Freemantle AM, Westcott JM, Napthine DV, O'Connor AJ. Anthelmintic resistance and sheep management practices in south western Victoria. Aust Vet J 1984; 61:248-51. [PMID: 6508667 DOI: 10.1111/j.1751-0813.1984.tb15532.x] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
Twenty-eight farms in 7 shires in south western Victoria were selected and tested for presence of benzimidazole-resistant nematodes between November 1979 and June 1981. Mean faecal egg counts of sheep were less than 100 strongyloid eggs/g on 11 farms. Faecal egg count reduction tests were conducted on the remaining 17 farms and thiabendazole was less than 90% efficient in reducing egg counts in sheep from 5 (29%) of these farms. Thiabendazole-resistant Teladorsagia circumcincta were identified at necropsy of experimentally infected treated sheep. In further studies a survey of 104 farms was conducted in the Mount Rouse and Dundas shires of western Victoria in 1981 and 1982 respectively to determine the prevalence of anthelmintic resistance in these shires. Mean faecal egg counts among weaner sheep in the winter-spring of both years were less than 100 eggs/g which indicated low levels of parasitic nematode populations. A faecal egg count reduction test was conducted on 10 farms and thiabendazole was less than 90% efficient on 3; levamisole was greater than 90% efficient in all 10 tests. Most of the surveyed farms carried Merino or Merino crossbred sheep at 10 to 15 dry sheep equivalents per ha and weaners were treated with anthelmintics 3 to 6 times per year. Management procedures based mainly on anthelmintic therapy were effective in controlling nematode populations in weaner sheep, although many producers alternated between different groups of anthelmintics within the same year contrary to current recommendations for long-term preservation of anthelmintic efficacy. It was concluded that anthelmintic resistance was not of practical importance to the majority of sheep producers in the region.
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Kawalek JC, Rew RS, Heavner J. Glutathione-S-transferase, a possible drug-metabolizing enzyme, in Haemonchus contortus: comparative activity of a cambendazole-resistant and a susceptible strain. Int J Parasitol 1984; 14:173-5. [PMID: 6735580 DOI: 10.1016/0020-7519(84)90045-6] [Citation(s) in RCA: 44] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
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Kettle PR, Vlassoff A, Lukies JM, Ayling JM, McMurtry LW. A survey of nematode control measures used by sheep farmers and of anthelmintic resistance on their farms. Part 1. North Island and the Nelson region of South Island. N Z Vet J 1981; 29:81-3. [PMID: 6946339 DOI: 10.1080/00480169.1981.34806] [Citation(s) in RCA: 46] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
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Kelly J, Whitlock H, Gunawan M, Griffin D, Porter C, Porter C, Martin I. Anthelmintic efficacy of low-dose phenothiazine against strains of sheep nematodes susceptible or resistant to thiabendazole, levamisole and morantel tartrate: effect on patent infections. Res Vet Sci 1981. [DOI: 10.1016/s0034-5288(18)32575-x] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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Prichard RK, Hall CA, Kelly JD, Martin IC, Donald AD. The problem of anthelmintic resistance in nematodes. Aust Vet J 1980; 56:239-51. [PMID: 7002142 DOI: 10.1111/j.1751-0813.1980.tb15983.x] [Citation(s) in RCA: 218] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
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