title: F200Y polymorphism in the β-tubulin gene in field isolates of Haemonchus contortus and risk factors of sheep flock management practices related to anthelmintic resistance.
abstract: Haemonchus contortus is the most prevalent and pathogenic nematode of sheep in tropical areas. The objectives of this study were to assess the frequency of the F200Y polymorphism on the β-tubulin gene in third-stage larvae of H. contortus from 33 sheep flocks in São Paulo state, Brazil, and to associate this frequency to risk factors based on farm management practices. The resistance allele frequency varied from 9 to 74%, and the resistance genotype frequency varied from 0 to 66.7%. Resistance genotype frequencies higher than 40% were associated with multiple risk factors - new sheep farming enterprises, the absence of farm records, the use of Dorper and Suffolk breeds, rotational grazing, the lack of wetlands on farms, pasture sharing with cattle or horses, frequent incorporation of animals into the flock, semi-intensive farming systems, whole-flock treatment, failure to use the FAMACHA method, lack of the dose-and-move practice, anthelmintic rotation after each application, visual estimation of animal weight for treatment, and lack of drug combination use. It can be concluded that genotyping the F200Y polymorphism can be used to monitor the resistance in sheep flocks and the knowledge of management strategies at the farm level is important to identify drug resistance related factors.
authors.affiliation: Embrapa Pecuária Sudeste, Rodovia Washington Luiz, km 234, 13560-970 São Carlos, SP, Brazil. simone@cppse.embrapa.br
authors.forename: Simone Cristina Méo
authors.initials: SC
authors.lastname: Niciura
authors.forename: Cecília José
authors.initials: CJ
authors.lastname: Veríssimo
authors.forename: Juliana Gracielle Gonzaga
authors.initials: JG
authors.lastname: Gromboni
authors.forename: Marina Ibelli Pereira
authors.initials: MI
authors.lastname: Rocha
authors.forename: Suelen Scarpa
authors.initials: SS
authors.lastname: de Mello
authors.forename: Cristina Maria Pacheco
authors.initials: CM
authors.lastname: Barbosa
authors.forename: Daniela Pontes
authors.initials: DP
authors.lastname: Chiebao
authors.forename: Daniel
authors.initials: D
authors.lastname: Cardoso
authors.forename: Giane Serafim
authors.initials: GS
authors.lastname: Silva
authors.forename: Ivani Pozar
authors.initials: IP
authors.lastname: Otsuk
authors.forename: José Roberto
authors.initials: JR
authors.lastname: Pereira
authors.forename: Luis Alberto
authors.initials: LA
authors.lastname: Ambrosio
authors.forename: Romeu Fernandes
authors.initials: RF
authors.lastname: Nardon
authors.forename: Tatiana Evelyn Hayama
authors.initials: TE
authors.lastname: Ueno
authors.forename: Marcelo Beltrão
authors.initials: MB
authors.lastname: Molento
mesh_terms: D000483:Alleles; D000818:Animals; D000871:Anthelmintics / Q000494:pharmacology* / Q000627:therapeutic use; D004351:Drug Resistance / Q000235:genetics; D005838:Genotype; D006188:Haemonchiasis / Q000188:drug therapy / Q000469:parasitology / Q000662:veterinary*; D006189:Haemonchus / Q000235:genetics*; D011110:Polymorphism, Genetic; D012307:Risk Factors; D012756:Sheep; D012757:Sheep Diseases / Q000469:parasitology*; D014404:Tubulin / Q000235:genetics*
chemical_list: D000871:Anthelmintics; D014404:Tubulin