title: Benzimidazole resistance of sheep nematodes in Norway confirmed through controlled efficacy test.
abstract: BACKGROUND
  Resistance against benzimidazoles (BZ) has recently been detected in Norwegian sheep flocks through a large scale prevalence survey based on the faecal egg count reduction test (FECRT). The use of this test in combination with bulk larval culture only gives an indication of which gastrointestinal nematodes genera that are involved and these results have to be confirmed by a controlled efficacy test (CET) to get accurate information about resistant nematodes populations at species level. A CET was therefore performed with larvae from two flocks where BZ resistance was previously detected through FECRT.
  
  
  RESULTS
  The latter test confirmed the previous results in both flocks. In flock A, the BZ resistant nematode population consisted solely of Haemonchus contortus, whereas H. contortus and Teladorsagia circumcincta comprised the resistant worm population in flock B.
  
  
  CONCLUSIONS
  Some discrepancies that have been recorded between FECRT and CET results regarding time for post-treatment coproscopical examination and a temporary suppression of faecal egg excretion are discussed.
authors.affiliation: Norwegian School of Veterinary Science, Sandnes, Norway. atle.domke@nvh.no
authors.forename: Atle V Meling
authors.initials: AV
authors.lastname: Domke
authors.forename: Christophe
authors.initials: C
authors.lastname: Chartier
authors.forename: Bjørn
authors.initials: B
authors.lastname: Gjerde
authors.forename: Snorre
authors.initials: S
authors.lastname: Stuen
mesh_terms: D000818:Animals; D000871:Anthelmintics / Q000494:pharmacology*; D001562:Benzimidazoles / Q000494:pharmacology*; D004351:Drug Resistance; D005260:Female; D006374:Helminthiasis, Animal / Q000453:epidemiology / Q000469:parasitology*; D007814:Larva / Q000145:classification / Q000187:drug effects / Q000254:growth & development; D008297:Male; D009664:Norway; D012756:Sheep; D012757:Sheep Diseases / Q000453:epidemiology / Q000469:parasitology*; D014251:Trichostrongyloidea / Q000145:classification / Q000187:drug effects* / Q000254:growth & development / Q000302:isolation & purification; D014252:Trichostrongyloidiasis / Q000453:epidemiology / Q000469:parasitology / Q000662:veterinary*
chemical_list: D000871:Anthelmintics; D001562:Benzimidazoles; C031000:benzimidazole