Reduced Efficacy of Ivermectin Treatments in Gastrointestinal NematodeInfections of Grazing Cattle in Japan

Journal of Veterinary Medical Science

Takuto DONOMOTO¹  Takashi OYAMADA¹  Yuki TERAZONO¹  Ryusuke TSUKADA¹  Toshiro YOSHIOKA¹  Yasushi WATANABE¹  Kensuke NAKAJIMA¹  Noboru KUDO¹  Shino TAKENOUCHI¹  Kaori HITOSUGI¹  Hiromi IKADAI¹ 

[1] Department of Veterinary Parasitology, School of Veterinary Medicine, Kitasato University, Towada, Aomori 034�?8628, Japan

关键词: anthelmintic resistance;    cattle;    Cooperia;    ivermectin;    Japan;   

DOI  :  10.1292/jvms.14-0243

学科分类：兽医学

来源: Japanese Society of Veterinary Science

【 摘 要 】

References(24)Fecal egg count reduction tests (FECRT) and larval migration inhibition tests(LMIT) were conducted to assess the efficacy of ivermectin (IVM) against gastrointestinalnematodes on 2 cattle farms in northern Japan in 2009 and 2010. Twelve to 20 calves oneach farm were treated topically with 0.5 mg IVM/kg 2 (Farm 2) or 4 times (Farm 1) duringthe grazing season (May–October). On Farm 1, fecal egg count (FEC) reduction at 14 dayspost-treatment ranged from 16 to 87% in 2009 and from 24 to 96% in 2010, with relativelylow reductions in August and October (16�?53%). Conversely, IVM treatment on Farm 2 reducedFEC by 97% in September 2009. Larvae obtained from fecal cultures and identified byPCR-RFLP analysis revealed that the dominant species on both farms prior to IVMadministration was Cooperia oncophora. In 2009, the FEC reduction ofC. oncophora on Farm 1 decreased from 85% in May to 56% in August. In2010, the reduction in C. oncophora in August was 28%. In the LMIT usinglarvae collected from the fecal cultures on Farm 1 in May and August 2009, theEC50 value of IVM in C. oncophora in August (0.892µg/ml) was 3 times higher than that in May (0.296µg/ml). The results of the LMIT corroborated the FECRTdata, indicating the presence of IVM-resistant C. oncophora on Farm 1, atleast in August. This is the first report of IVM-resistant nematodes in Japanesecattle.

【 授权许可】

Unknown