Multiple resistance of gastrointestinal nematodes to nine different drugs in a sheep flock in southern Brazil.
Based on clinical observation of a flock of approximately 5000 sheep (breed Merino) from southern Brazil, the failure of anthelmintic treatments was suspected. The sensitivity of the gastrointestinal nematodes that infected these sheep to nine drugs (Levamisole, Moxidectin, Albendazole, Ivermectin, Nitroxynil, Disophenol, Trichlorphon, Closantel, and a combination of Ivermectin, Levamisole and Albendazole) was evaluated. None of the drugs reduced the count of nematode eggs per gram of feces (EPG) in the sheep to an adequate extent (defined as a 95% reduction in EPG). Therefore, we found multiple parasite resistance to all classes of anthelmintic drugs available for small ruminants in the Brazilian market. The genera Haemonchus spp., Trichostrongylus spp. and Ostertagia spp. had various degrees of resistance (or natural tolerance) to each of the drug treatments.
Cezar
Alfredo Skrebsky
AS
Departamento de Medicina Veterinária Preventiva (DMVP), Centro de Ciências Rurais (CCR), Universidade Federal de Santa Maria (UFSM), 97105-900 Santa Maria, RS, Brazil. alfredosps@hotmail.com
Toscan
Gustavo
G
Camillo
Giovana
G
Sangioni
Luís Antônio
LA
Ribas
Henrique Olmedo
HO
Vogel
Fernanda Silveira Flôres
FS
D000818:Animals; D000871:Anthelmintics / Q000494:pharmacology* / Q000627:therapeutic use; D001938:Brazil / Q000453:epidemiology; D018432:Drug Resistance, Multiple; D007814:Larva / Q000187:drug effects; D009348:Nematoda / Q000187:drug effects*; D009349:Nematode Infections / Q000188:drug therapy / Q000453:epidemiology / Q000662:veterinary*; D012756:Sheep; D012757:Sheep Diseases / Q000188:drug therapy / Q000453:epidemiology / Q000469:parasitology*
D000871:Anthelmintics