A dual anthelmintic treatment strategic scheme for the control of fasciolosis in dairy sheep farms.

A clinical longitudinal field trial was conducted on a dairy sheep farm in southern Italy to assess the effectiveness of a novel anthelmintic treatment strategic scheme against Fasciola hepatica. The scheme utilizes a dual anthelmintic treatment (DAT), i.e., the use of either one of two different anthelmintics on the flock, albendazole sulphoxide (SO) at 1-month intervals and rafoxanide at 2-month intervals, administered to the lactating and non-lactating animals, respectively. The DAT strategic scheme lasted 3 years. In Year 1 and Year 2, shotgun monthly DATs for 5 consecutive months (July, August, September, October, and November) were performed on the flock. In Year 3 there was only one monthly DAT, in July. Overall, the DAT scheme reduced the prevalence of F. hepatica infection by 94.4% (from an average prevalence of 71.1% during the pre-DAT period to an average prevalence of 4.0% during Year 3), and the eggs/gram of faeces (EPG) from 29.3 to 1.3. In conclusion, the DAT strategic scheme reported in the present study successfully reduced both the prevalence and EPGs of F. hepatica to a level at which there were no longer any clinical symptoms of the disease. This scheme did not influence the albendazole SO efficacy against GI nematodes and might be used for the treatment of fasciolosis in dairy sheep farms.