title: Assessment of flukicide efficacy against Fasciola hepatica in sheep in Sweden in the absence of a standardised test.
abstract: Anthelmintic resistance (AR) to Fasciola hepatica is emerging worldwide. Recently, AR to the adulticide compound albendazole (ABZ) was shown in Argentina and Spain. In Sweden, ABZ treatment failure against F. hepatica was first reported in sheep in 2012. The present study tested the efficacy of ABZ and triclabendazole (TCBZ) in sheep naturally infected with F. hepatica using a combination of three different diagnostic methods: faecal egg counts (FEC), coproantigen ELISA (cELISA) and Fasciola egg hatch test (FEHT). Two deworming trials, in November 2014 and January 2015, were performed on two sheep farms (farms A and B) in south-western Sweden. Except ABZ in November, treatment with ABZ or TCBZ achieved sufficient efficacy (97-100%) against adult F. hepatica on farm A. In contrast, ABZ treatment failed in the sheep flock on farm B, despite low initial faecal egg output. On farm B, ABZ efficacy based on FEC was 67% (95% CI: 35-84) and four of eight ewes tested were coproantigen-positive 21 days post-treatment. Ovicidal activity of ABZ against Fasciola eggs in isolates from both farms and one additional bovine isolate were tested by FEHT to exclude the presence of juvenile flukes and other factors such as dosing failure and poor quality of drug product. Irrespective of drug trial, data from FEHT showed significantly lower ovicidal activity of ABZ for the ovine farm B isolate than for the isolate from farm A. This confirms that the low efficacy of ABZ in sheep flock B was associated with ABZ resistance. Overall, the usefulness of three complementary methods for detection of ABZ resistance in the field was demonstrated.
authors.affiliation: Department of Biomedical Sciences and Veterinary Public Health, Section for Parasitology, Swedish University of Agricultural Sciences (SLU), 75007, Uppsala, Sweden. Electronic address: adam.novobilsky@slu.se.
authors.forename: Adam
authors.initials: A
authors.lastname: Novobilský
authors.affiliation: Department of Biomedical Sciences and Veterinary Public Health, Section for Parasitology, Swedish University of Agricultural Sciences (SLU), 75007, Uppsala, Sweden.
authors.forename: Natalia
authors.initials: N
authors.lastname: Amaya Solis
authors.affiliation: Department of Biomedical Sciences and Veterinary Public Health, Section for Parasitology, Swedish University of Agricultural Sciences (SLU), 75007, Uppsala, Sweden.
authors.forename: Moa
authors.initials: M
authors.lastname: Skarin
authors.affiliation: Department of Biomedical Sciences and Veterinary Public Health, Section for Parasitology, Swedish University of Agricultural Sciences (SLU), 75007, Uppsala, Sweden.
authors.forename: Johan
authors.initials: J
authors.lastname: Höglund
mesh_terms: D015766:Albendazole / Q000008:administration & dosage* / Q000494:pharmacology; D000818:Animals; D000871:Anthelmintics / Q000008:administration & dosage* / Q000494:pharmacology; D000947:Antigens, Helminth / Q000032:analysis; D001562:Benzimidazoles / Q000008:administration & dosage* / Q000494:pharmacology; D002470:Cell Survival / Q000187:drug effects; D004351:Drug Resistance; D004797:Enzyme-Linked Immunosorbent Assay; D005210:Fasciola hepatica / Q000187:drug effects* / Q000302:isolation & purification; D005211:Fascioliasis / Q000188:drug therapy / Q000662:veterinary*; D005243:Feces / Q000737:chemistry / Q000469:parasitology; D010270:Parasite Egg Count; D012756:Sheep; D012757:Sheep Diseases / Q000188:drug therapy*; D013548:Sweden; D016896:Treatment Outcome; D000077682:Triclabendazole; D015053:Zygote / Q000187:drug effects / Q000502:physiology
chemical_list: D000871:Anthelmintics; D000947:Antigens, Helminth; D001562:Benzimidazoles; D000077682:Triclabendazole; D015766:Albendazole
keywords: Albendazole; Coproantigen ELISA; Egg hatch test; Faecal egg count; In vitro; Liver fluke; Resistance