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Anthelmintic resistance in the field: Changes in resistance status of parasitic populations in response to anthelmintic treatment
Author(s) -
WALLER PJ,
DOBSON RJ,
AXELSEN A.
Publication year - 1988
Publication title -
australian veterinary journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.382
H-Index - 59
eISSN - 1751-0813
pISSN - 0005-0423
DOI - 10.1111/j.1751-0813.1988.tb14276.x
Subject(s) - anthelmintic , levamisole , oxfendazole , benzimidazole , biology , fenbendazole , ostertagia , veterinary medicine , resistance (ecology) , drug resistance , moxidectin , medicine , agronomy , ecology , zoology , microbiology and biotechnology , chemistry , organic chemistry
SUMMARY: Changes in anthelmintic resistance in nematode parasites were monitored in sheep grazing on 2 separate farms, but with the same anthelmintic treatment program, over 16 years. High levels of benzimidazole resistance emerged in Ostertagia and Trichostrongylus spp populations on both farms following 9 years of continuous use of this class of drug. Subsequently, variations in the levels of resistance occurred for the same species between farms and between species on the same farm. A change to levamisole for 2 years resulted in a significant reversion towards benzimidazole susceptibility, but a concomitant rise in levamisole resistance, in Ostertagia on one farm. However, benzimidazole resistance increased rapidly following the re‐introduction of oxfendazole into the anthelmintic treatment program. Results from both farms illustrate the pitfalls of using one anthelmintic class for an extended period and provide indirect support for the alternation of anthelmintic classes at approximately yearly intervals.