Fasciola hepatica: spread of albendazole resistance in Central Eastern Argentina Cesar I. Pruzzo1*, Rodrigo Sanabria1,2, Daniel Medus3, Giussepe Reyna4, Jorge Romero1 1 Facultad de Cs. Veterinarias, Universidad Nacional de La Plata, Argentina. 2 CONICET, Argentina.3 INTA Concepción del Uruguay, Argentina. 4 Facultad de Cs. Veterinarias, Universidad Nacional de Cajamarca, Perú. *E-mail: cpruzzo@fcv.unlp.edu.ar Recently, a Fasciola hepatica field isolate resistant to albendazole (ABZ) and susceptible to triclabendazole (TCBZ) was recovered from sheep of Entre Ríos province, Argentina (32°02’S, 60°16’W). In order to know about the regional status of resistance to drugs, a FECRT test was carried out on cattle. Four farms located at approximately 150 km around of the former description were selected. They belonged to the departament of Gualeguay (Gy), Gualeguaychu (Gch), Rosario del Tala (Rt) and Concepcion del Uruguay (Cu) (Figure 1). Sixty cows per farm were assigned to four groups according to the treatments they received, as follows: ABZ group, 10 mg/Kg (n=15); TCBZ group, 10 mg/Kg (n=15); G3, Closantel group (CSTL) 15 mg/kg (n=15); G4, untreated controls (n=15). On day 0 cattle were drenched and sampled for feces. Fecal samples were taken again on days 7 and 21 post treatment. ABZ resistance was detected in all the farms, giving by the following efficacy percentages (upper and lower limits of 95% confidence interval):Gy farm: ABZ 47% (70-25), TCBZ 100%, CSTL 93%(100-81); Gch farm: ABZ 25% (47-3), TCBZ 100% (100-100), CSTL 90% (100-76); Rt farm: ABZ 0%, TCBZ 100%, CSTL 100%; Cu: ABZ 0%, TCBZ 100%, CSTL 96% (100-86).(fig2) Figure 1-Satellital images (Google Earth) of Entre Ríos province, Argentina (left, upper right), and specific location of the farms (stars, lower right image) where the efficacy tests were carried out. ABZ resistance seems to be widely spread in the studied region, although ABZ drenching is not quite frequent. Other possibilities might be considered, like the transport of snails infected with resistant F.hepatica larvae across the basins. This situation may specially take place in rainy seasons, when farms become flooded and snails can be easily spread. Figure 2. Triclabendazole (TCBZ, green bars), Albendazole (ABZ, blue bars), and Closantel (CSTL, orange bars) efficacy against F. hepatica at day 21 post treatment in the four tested farms. Upper and lower 95% confidence interval limits (black lines) are also displayed. This study was partially supported by ANPCyT (PICT 2012-2829), Ministerio de Ciencia, Tecnología e Innovación Productiva, Argentina. References: Canevari J, Ceballos L, Sanabria R, Romero J, Olaechea F, Ortiz P, Cabrera M, Gayo V, Fairweather I, Lanusse C, Alvarez L. 2014. Testing albendazole resistance in Fasciola hepatica: validation of an egg hatch test with isolates from South America and the United Kingdom. J Helminthol. 88(3):286-92. Sanabria R, Ceballos L, Moreno L, Romero J, Lanusse C, Alvarez L. 2013. Identification of a field isolate of Fasciola hepatica resistant to albendazole and susceptible to triclabendazole. Vet Parasitol. 193(1-3):105-10. References: