title: Anthelmintic resistance in cattle nematode in the western Pampeana Region of Argentina.
abstract: During the past three years there have been several reports of cattle anthelmintic resistance (AR) in Argentina. Twenty-five cattle herds in the west fattening area of the Pampeana Region were surveyed to assess the prevalence of AR and the species of nematode involved. The survey involved fattening and cow-calf systems with a mean of 6760 bovines. Resistance was determined in vivo by a faecal egg count reduction test (FECRT). Efficacies from the World Association for the Advancement of Veterinary Parasitology (WAAVP) formula were compared with those obtained from the Abbott formula. Sixty 6-12-month-old calves were selected from each property and divided into four groups, namely, IVM (ivermectin, 0.2mg/kg), BZD (fenbendazole, 5mg/kg or albendazole 7.5mg/kg), LVM (levamisole, 7.5mg/kg) and Control (untreated group). Nematode larvae were identified by four pooled faecal cultures for each group. Cooperia and Ostertagia were the predominant nematode larvae in pre-treatment cultures. The mean FECRT efficacies for IVM, BZD and LVM were 81.0+/-21%, 93.3+/-8% and 97.6+/-4%, respectively. AR was detected in 16 (64%) herds. IVM resistance was present in 15 herds and BZD resistance in eight herds (32%). Resistance to both ivermectin and fenbendazole was present in seven herds. LVM resistance was not detected. Cooperia was the predominant post-treatment nematode in all the herds with IVM resistance. In one herd with IVM resistance, Ostertagia counts were slightly increased over pretreatment counts. Ostertagia was the prevalent post-treatment genera in herds with BZD resistance. A high level of resistance to ivermectin was recorded in this fattening region of Argentina. Also several herds with resistance to benzimidazole were observed. These results show the importance of AR in Argentinian cattle production. High correlation between WAAVP and Abbott formulae was observed. However, under some uncertain diagnosis, both formulae could be applied as complementary to help result interpretations.
authors.affiliation: INTA-Estación Experimental Agropecuaria de Anguil, CC 11, 6326 Anguil, La Pampa, Argentina. vsuarez@anguil.inta.gov.ar
authors.forename: V H
authors.initials: VH
authors.lastname: Suarez
authors.forename: S L
authors.initials: SL
authors.lastname: Cristel
mesh_terms: D015766:Albendazole / Q000627:therapeutic use; D000818:Animals; D000969:Antinematodal Agents / Q000627:therapeutic use*; D001118:Argentina; D002417:Cattle; D002418:Cattle Diseases / Q000188:drug therapy*; D004305:Dose-Response Relationship, Drug; D004351:Drug Resistance; D005243:Feces / Q000469:parasitology; D005260:Female; D005273:Fenbendazole / Q000627:therapeutic use; D007559:Ivermectin / Q000627:therapeutic use; D007978:Levamisole / Q000627:therapeutic use; D008297:Male; D009348:Nematoda / Q000187:drug effects*; D009349:Nematode Infections / Q000188:drug therapy / Q000662:veterinary*; D010270:Parasite Egg Count / Q000662:veterinary; D021261:Parasitic Sensitivity Tests / Q000662:veterinary; D011897:Random Allocation; D016896:Treatment Outcome
chemical_list: D000969:Antinematodal Agents; D007978:Levamisole; D005273:Fenbendazole; D007559:Ivermectin; D015766:Albendazole