Comparative ovicidal effect of albendazole and triclabendazole on Fasciola hepatica eggs.

MORENO, G; ALVAREZ, L; MORENO, L; CEBALLOS, L; SHAW, L; FAIRWEATHER, I; LANUSSE, C

Gent, Belgium

Congreso; 21sh International Conference of the World Association for the Advancement of Veterinary Parasitology.; 2007

Comparative ovicidal effect of albendazole and triclabendazole on Fasciola hepatica eggs  Moreno G. 1, Alvarez L. 1, Moreno L. 1, Ceballos L. 1, Shaw L. 2, Fairweather I. 2, Lanusse C1. 1Laboratorio de Farmacología, Facultad de Ciencias Veterinarias, Universidad Nacional del Centro, Tandil, Argentina and CONICET, Argentina; 2School of Biology and Biochemistry, Medical Biology Centre, The Queen´s University of Belfast, Belfast, Northern Ireland, UK. The benzimidazole compounds albendazole (ABZ) and triclabendazole (TCBZ) are both effective against Fasciola hepatica, although ABZ is only effective against adult flukes. Additionally, ABZ is a broad-spectrum nematodicidal compound with well-known ovicidal activity. However, as far as we know no data on the ovicidal effect of TCBZ against F. hepatica eggs are available. The work reported here evaluated the comparative ovicidal effect of ABZ and TCBZ on F. hepatica eggs (500 eggs/ml, n= 4) recovered from bile of sheep artificially infected with either a TCBZ-susceptible (Cullompton) or a -resistant (Sligo) F. hepatica isolate. Eggs were incubated with TCBZ, TCBZ-sulphoxide (TCBZSO), ABZ, ABZ-sulphoxide (ABZSO) (5 nmol/mL) or without drug (untreated control).  The drug molecules were removed by several wash cycles after 12 h. Miracidial development (egg hatch) was evaluated after 15 days of incubation (25ºC) by direct microscope observation. A similar egg hatch rate was observed in the untreated control and in eggs incubated with TCBZ or TCBZSO collected from sheep infected with both the TCBZ-susceptible and -resistant isolates. However, a significant (P<0.05) inhibition of the egg hatch was observed in ABZ- and ABZSO-incubated eggs. In conclusion, ABZ and ABZSO had a clear inhibitory effect on F. hepatica egg development. However, the most extensively used flukicidal compound, TCBZ, and its main sulphoxide metabolite, did not affect the egg hatch even in susceptible flukes. These findings complement previous work on the understanding of the comparative flukicidal activity of TCBZ and ABZ, and may be important to optimise fluke control in the field.