Evaluation of the efficacy of nitroxynil in natural infections of Fasciola hepatica in a farm with resistant sheep against triclabendazole | Evaluación de la eficacia del nitroxinil en infecciones naturales de Fasciola hepatica en una explotación de ovino resistente al triclabendazol
2009
Martínez Valladares, M., Universidad de León (España). Facultad de Veterinaria | Famularo, M.R., Universidad de León (España). Facultad de Veterinaria | Fernández Pato, N., Universidad de León (España). Facultad de Veterinaria | Castañón Ordóñez, L., Universidad de León (España). Facultad de Veterinaria | Rojo Vázquez, F.A., Universidad de León (España). Facultad de Veterinaria
In Spain the infection by F. hepatica is widely distributed. According to coprological analysis, around the 30% of flocks in the Northwest part of the country are infected, reaching higher levels (56%), when the immunological diagnosis is carried out. The control is based on the use of fasciolicides, some of them very efficient against adult forms. However, the wrong use of them, the management and other factors favoures the development of resistance flukes. The aim of the present study was to evaluate the efficacy of the drug nitroxynil in a farm previously identified as resistant to triclabendazole. After measuring the eggs per gram (epg) in faeces along the assay we observed significant differences between the treated groups and the control group. The FECRT (faecal egg count reduction test) was carried out per day in each treated group, compared to the control group. The results showed an efficacy between 47-79% in the triclabendazol group. These values confirmed the presence of resistance to this drug since under normal conditions has an efficacy of 90% against immature flukes and of 99-100% against adult worms. However, the efficacy of nitroxynil is lower than triclabendazole; between 50-90% against forms with 7-9 weeks old and between 91-99% in adult forms. In this case, we observed an efficacy during the first month of the assay around 76-79% for the nitroxynil. We also measured the level of IgG against excretion-secretion antigen of F. hepatica. Significant differences were described between treated groups and the control group. Moreover, a negative significant correlation was found with the epg the day 17 pt, the lower is the level of epg, the higher is the level of IgG. We conclude that the efficacy of the nitroxynil in this farm is better than the efficacy of the triclabendazole, even without getting the 90% of efficacy.
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