02250naa a2200253 a 450000100080000000500110000800800410001902400420006010000170010224501460011926000090026552013840027465000140165865300190167265300270169165300180171865300430173665300270177970000220180670000200182870000260184870000280187477300940190219728392017-09-21       2013    bl uuuu     u00u1 u    #d7 a10.1590/S1984-29612013000400015.2DOI1 aNUNES, R. L.  aFrequency of benzimidazole resistance in Haemonchus contortus populations isolated from buffalo, goat and sheep herds.h[electronic resource]  c2013  aAnthelmintic resistance is an increasing problem that threatens livestock production worldwide. Understanding of the genetic basis of benzimidazole resistance recently allowed the development of promising molecular diagnostic tools. In this study, isolates of Haemonchus contortus obtained from goats, sheep and buffaloes raised in Brazil were screened for presence of the polymorphism Phe200Tyr in the β -tubulin 1 gene, which confers resistance to benzimidazole. The allelic frequency of the mutation conferring resistance ranged from 7% to 43%, and indicated that resistance to benzimidazole could be found in nematodes isolated from all the ruminant species surveyed. Although significant variation in the frequency of the F200Y mutation was observed between different herds or host species, no significant variation could be found in populations isolated from animals within the same herd. These findings suggest that screening of samples from a few animals has the potential to provide information about the benzimidazole resistance status of the entire herd, which would enable a considerable reduction in the costs of diagnosis for the producer. Molecular diagnosis has practical advantages, since it can guide the choice of anthelmintic drug that will be used, before its application in the herd, thus reducing the economic losses driven by anthelmintic resistance.  aGenética  aBenzimidazóis  aDiagnóstico molecular  aPolimorfismos  aResistência a drogas anti-helmíntico  aRuminantes domésticos1 aSANTOS, L. L. dos1 aBASTIANETTO, E.1 aOLIVEIRA, D. A. A. de1 aBRASIL, B. dos S. A. F.  tRevista Brasileira de Parasitologia Veterinária, Jaboticabalgv. 22, n. 4, p. 1-6, 2013.