Triclabendazole resistance in Fasciola hepatica: First report in sheep from the Santa Cruz province, Argentinian Patagonia

LARROZA, MARCELA; AGUILAR, MARCELO; SOLER, PAULA; MORA, JULIO; ROA, MARTÍN; CABRERA, RAÚL; MARTINEZ STANZIOLA, JUAN P.; CEBALLOS, LAURA; ALVAREZ, LUIS I.

Veterinary Parasitology: Regional Studies and Reports

Elsevier

Año: 2023 vol. 45

2405-9390

In the fall of 2022, decreased triclabendazole (TCBZ) efficacy against F. hepatica was suspected in a sheep farmlocated in the Santa Cruz province, Argentinian Patagonia. Since TCBZ-resistance in F. hepatica has never beenreported in this province, this study aimed to confirm potential TCBZ-resistance in F. hepatica and to evaluate theefficacy of closantel (CLO) and nitroxinil (NTX), through faecal egg count reduction test (FECRT), and the efficacyof albendazole (ABZ) through the in vitro egg hatch test (EHT) in sheep. Sixty-eight (68) animals wereselected from a herd of eighty (80) female Merino naturally infected with F. hepatica based on eggs per gram ofF. hepatica (EPGFh) counts and assigned into four (4) groups (n = 17 per group): Group Control, animals did notreceive anthelmintic treatment; Group TCBZ, animals were orally treated with TCBZ (12 mg/kg); Group CLO,animals were orally treated with CLO (10 mg/kg); and Group NTX, animals were subcutaneously treated withNTX (10 mg/kg). The fluke egg output was monitored on days 0 and 21 post-treatment. For the EHT, liver flukeeggs were isolated from faecal samples (approx. 50 g) collected from animals of the control group. TCBZ efficacyagainst liver fluke was 53.4%, confirming the presence of TCBZ-resistant isolates on the farm. CLO and NTX werehighly effective (100%) for the treatment of F. hepatica on this farm. The EHT was carried out in two differentlaboratories, in which was observed an ABZ efficacy of 95.8 (Bariloche) and 96.5% (Tandil). These resultsindicate the ABZ susceptibility of this F. hepatica isolate and the inter-laboratory precision of the test.