title: [How widespread is resistance to invermectin among gastrointestinal nematodes in sheep in The Netherlands?].
abstract: In Autumn 2009, a faecal egg count reduction test (FERCT) was carried out on three sheep farms. Groups of 8-11 lambs were treated with ivermectin or moxidectin, with a 14-day interval between treatment and sampling. Ivermectin resistance was present on all three farms. Treatment with ivermectin resulted in a reduction in faecal egg numbers of 94.6%, 63%, and 59%. On two farms, 14 days after treatment pooled faecal samples yielded predominantly larvae of Hamonchus contortus (100% and 98%, respectively). On the third farm, H. contortus and (probably) Teladorsagia circumcincta were resistant to ivermectin (64% and 36% of the larvae, respectively). Treatment with moxidectin resulted in a 100% reduction in egg output in sheep on all three farms. More sensitive culture techniques failed to detect any larvae in samples taken from two farms, but a few Ostertagia-type larvae, probably of T. circumcincta, were detected in samples from the third farm. It can be concluded that gastrointestinal nematodes in sheep from these three farms were resistant to ivermectin, whereas resistance to moxidectin was not detected.
authors.affiliation: Centraal Veterinair Instituut van Wageningen U R, Postbus 65, 8200 AB Lelystad. fredborgsteede@hotmail.com
authors.forename: Fred
authors.initials: F
authors.lastname: Borgsteede
authors.forename: Jan
authors.initials: J
authors.lastname: Verkaik
authors.forename: Lammert
authors.initials: L
authors.lastname: Moll
authors.forename: Daan
authors.initials: D
authors.lastname: Dercksen
authors.forename: Piet
authors.initials: P
authors.lastname: Vellema
authors.forename: Gerhard
authors.initials: G
authors.lastname: Bavinck
mesh_terms: D000818:Animals; D000831:Animals, Newborn; D000969:Antinematodal Agents / Q000494:pharmacology*; D004351:Drug Resistance; D005243:Feces / Q000469:parasitology; D005260:Female; D006188:Haemonchiasis / Q000188:drug therapy / Q000662:veterinary; D006189:Haemonchus / Q000187:drug effects; D007411:Intestinal Diseases, Parasitic / Q000188:drug therapy / Q000662:veterinary*; D007559:Ivermectin / Q000494:pharmacology*; D008297:Male; D009426:Netherlands; D010028:Ostertagia / Q000187:drug effects; D010029:Ostertagiasis / Q000188:drug therapy / Q000662:veterinary; D010270:Parasite Egg Count / Q000662:veterinary; D012756:Sheep; D012757:Sheep Diseases / Q000188:drug therapy*
chemical_list: D000969:Antinematodal Agents; D007559:Ivermectin