title: The prevalence of anthelmintic resistance in nematode parasites of sheep in southern Latin America: Paraguay.
abstract: This survey to detect anthelmintic resistance in nematode parasites of sheep was conducted on 11 farms in the Occidental and 26 farms in the Oriental Regions of Paraguay using the faecal egg count reduction test (FECRT). The anthelmintic groups tested were the benzimidazoles, levamisole and avermectins (both oral and injectable). Overall the levels of resistance were 73%, 68%, 73% and 47%, respectively. Levels of resistance were similar for all three important nematode genera, viz. Haemonchus contortus, Ostertagia and Trichostrongylus. This survey clearly indicates that a large, and ever increasing, proportion of sheep farmers are rapidly approaching the time when they will have exhausted all chemotherapeutic options to control parasites. Unless they face having to abandon their sheep farming operations, radical changes will need to be implemented with urgency.
authors.affiliation: Ministry of Agriculture, LIDIAV, San Lorenzo, Paraguay.
authors.forename: S
authors.initials: S
authors.lastname: Maciel
authors.forename: A M
authors.initials: AM
authors.lastname: Giménez
authors.forename: C
authors.initials: C
authors.lastname: Gaona
authors.forename: P J
authors.initials: PJ
authors.lastname: Waller
authors.forename: J W
authors.initials: JW
authors.lastname: Hansen
mesh_terms: D000818:Animals; D000871:Anthelmintics / Q000627:therapeutic use*; D003710:Demography; D018432:Drug Resistance, Multiple; D006189:Haemonchus / Q000187:drug effects; D009348:Nematoda / Q000187:drug effects*; D009349:Nematode Infections / Q000188:drug therapy / Q000662:veterinary*; D010028:Ostertagia / Q000187:drug effects; D010239:Paraguay; D010270:Parasite Egg Count; D012756:Sheep / Q000469:parasitology*; D012757:Sheep Diseases; D014254:Trichostrongylus / Q000187:drug effects
chemical_list: D000871:Anthelmintics