Monepantel-based anthelmintic treatment induces shifts in gastrointestinal microbiota in sheep

Abstract

Background and Aims: Gastrointestinal nematodes remain one of the most significant biological constraints to sustainable livestock production worldwide, with well-recognized economic and productivity losses. Beyond their direct effects on the host, there is growing recognition that nematode colonization actively shapes the gastrointestinal (GI) environment, altering the ecological niche where parasites and microbial communities coexist. Methods: In this context, understanding bacteria–nematode interactions has become increasingly relevant for the development of innovative and integrative parasite control strategies. The goal of the current study was to assess how a monepantel-based anthelmintic treatment influences GI microbial communities in sheep. Results: Seventeen (17) days after treatment, only a low number of Oesophagostomum radiatum and Trichuris ovis were recovered from the large intestine of treated animals, indicating effective nematode reduction. Concomitantly, marked shifts in the abomasal microbiota were observed following treatment, including a significant decrease in the bacterial family Mycoplasmataceae family (Log2FC= -4, Padj= 0.001) and a pronounced increase in Methanobacteriaceae (Log2FC= 2.9, Padj= 0.018). These changes suggest that monepantelinduced nematode removal is associated with rapid restructuring of abomasal microbial community. Conclusions: Although the mechanistic basis of interactions among mycoplasmas, methanogenic archaea and nematode populations requires further investigation, our results support the concept that parasite control interventions can have broader ecological consequences within the GI ecosystem, highlighting the potential of parasite–bacterial community interactions as a novel framework for the development of innovative and sustainable parasite control strategies.