An experimental study on triclabendazole resistance of Fasciola hepatica in sheep

The efficacy of triclabendazole in sheep experimentally infected with Fasci ola hepatica was studied. Two groups of 12 lambs were infected with a susce ptible (S) or a resistant (R) strain of F: hepatica. Eight weeks after infe ction, six lambs of each group (ST and RT) were treated with triclabendazol e (10 mg/kg). The other lambs were used as untreated controls (SC and RC). The parameters studied were: GLDH, gamma -GT, ELISA measuring antibodies ag ainst recombinant cathepsin-L-1 and eggs per gram faeces (epg). The lambs w ere slaughtered 16 weeks after infection and the number of flukes counted. The GLDH, gamma -GT levels and the OD value of the ELISA decreased as a res ult of the treatment in group ST. Patent infections were observed in all an imals of groups SC, RT and RC. In group ST, occasionally a few eggs were fo und in five lambs. The percentage of flukes was 31.3 in SC and 37.6 in RC. In the treated groups ST and RT, the percentage of flukes was 0.06 and 33.6 , respectively. These results corresponded to efficacies of 99.8% in the su sceptible and 10.8% in the resistant strain. Since the resistant strain was isolated from a mixed cattle and sheep farm, it confirms the presence of t riclabendazole resistance in the Netherlands. (C) 2001 Elsevier Science B.V . All rights reserved.