Título:	Resistance reversion after Haemonchus contortus replacement in a sheep flock: monitoring of benzimidazole and levamisole resistance-associated polymorphisms and impact on lamb survival.
Autoria:	NICIURA, S. C. M. CORRÊA, L. G. P. IBELLI, A. M. G. BELLO, H. J. S. OKINO, C. H. CHAGAS, A. C. de S.
Afiliação:	SIMONE CRISTINA MEO NICIURA, CPPSE; LORRANE GABRIELE PINHEIRO CORRÊA, UNIVERSIDADE ESTADUAL PAULISTA JÚLIO DE MESQUITA FILHO; ADRIANA MERCIA GUARATINI IBELLI, CPPSE; HORNBLENDA JOAQUINA SILVA BELLO, FUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULO; CINTIA HIROMI OKINO, CPPSE; ANA CAROLINA DE SOUZA CHAGAS, CPPSE.
Ano de publicação:	2026
Referência:	BMC Veterinary Research, v. 22, article number 91, 2026.
Conteúdo:	Haemonchus contortus is a highly prevalent gastrointestinal nematode whose control is hindered by anthelmintic resistance. Worm replacement (WR), where a resistant parasite population is substituted for a susceptible one, was performed through an artificial infection of nematode-free ewes with a susceptible H. contortus isolate. The infected ewes were kept in a nematode-free paddock (total replacement—TR) or in a paddock naturally infested with resistant helminths (partial replacement—PR) and compared to untreated ewes kept in a naturally infested paddock (control—C). Lambs born in each group, over two breeding seasons, were evaluated from 63 to 189 days old and subjected to lifesaving anthelmintic treatments (AHt) with the combination of benzimidazole and levamisole when fecal egg counts (FEC) ≥ 10,000 and packed cell volume (PCV) ≤ 24% or when PCV ≤ 22%, and a Kaplan–Meier survival analysis of the AHt requirement was performed. Benzimidazole (F200Y) and levamisole (S168T) resistance-associated polymorphisms were genotyped in H. contortus every six months after WR.
Thesagro:	Haemonchus Contortus Rebanho Ovelha Polimorfismo Benzimidazol Cordeiro
NAL Thesaurus:	Anthelmintics Sheep Benzimidazole Levamisole Polymorphism
Palavras-chave:	Allelic discrimination genotyping Anthelmintic resistance Survival probability Worm replacement
ISSN:	1746-6148
Digital Object Identifier:	https://doi.org/10.1186/s12917-025-05156-2
Tipo do material:	Artigo de periódico
Acesso:	openAccess
Aparece nas coleções:	Artigo em periódico indexado (CPPSE)