title: Detection of ivermectin resistance by a larval development test--back to the past or a step forward?
abstract: The aim of this study was to evaluate the potential of the larval development test for the detection of ivermectin (IVM) resistance in Haemonchus contortus of sheep. Single infections with 5000 third-stage larvae of five resistant and two susceptible isolates of H. contortus were given to sheep. Fecal samples were collected four times during patency, and the micro-agar version of the larval development test (MALDT) was performed. Three macrocyclic lactone drugs (IVM, eprinomectin and IVM aglycone) were tested. The results of the tests are presented as LC50 and LC99 values. The MALDT was well able to distinguish between susceptible and resistant isolates. Resistance factors (RF) for the LC99 values were generally higher than those obtained by comparing LC50 values. The highly resistant isolates were readily distinguishable from the susceptible isolates, particularly when using IVM aglycone and eprinomectin, with RFs above 20.
authors.affiliation: Institute of Parasitology, Slovak Academy of Sciences, Hlinkova 3, 040 01 Košice, Slovakia.
authors.forename: M
authors.initials: M
authors.lastname: Dolinská
authors.forename: A
authors.initials: A
authors.lastname: Königová
authors.forename: V
authors.initials: V
authors.lastname: Letková
authors.forename: L
authors.initials: L
authors.lastname: Molnár
authors.forename: M
authors.initials: M
authors.lastname: Várady
mesh_terms: D000818:Animals; D000871:Anthelmintics / Q000494:pharmacology*; D004351:Drug Resistance; D006189:Haemonchus / Q000187:drug effects*; D007559:Ivermectin / Q000494:pharmacology*; D007814:Larva / Q000187:drug effects; D007928:Lethal Dose 50; D012756:Sheep; D012757:Sheep Diseases / Q000469:parasitology
chemical_list: D000871:Anthelmintics; D007559:Ivermectin
keywords: Anthelmintic resistance; Haemonchus contortus; In vitro detection; Ivermectin