Epsilon Archive for Student Projects

Abstract

Gastrointestinal nematodes are a major constraint to sheep production due to their impact on animal health, productivity, and the increasing prevalence of anthelmintic resistance (AR). In this study, the efficacy of ivermectin (IVM) and fenbendazole (FBZ) was assessed using Fecal Egg Count Reduction Test (FECRT). In addition, the performance of an Artificial Intelligence (AI) assisted microscopy platform OvaCyteTM (OC) was compared with droplet digital Polymerase Chain Reaction (ddPCR) for the detection and quantification of gastrointestinal nematodes in naturally infected Swedish lambs, with particular focus on H. contortus.
Twenty lambs 5-6 months old Gotlandic sheeps were randomly allocated to treatment with either IVM (0.2 mg/kg orally) or FBZ (5 mg/kg orally) and sampled at 1, 2, 3, and 4 weeks post-treatment, with a final follow-up sample collected six months later. Faecal samples were analysed using OC and ddPCR targeting the ITS2 region of ribosomal deoxyribonucleic acid (DNA). OC showed strong agreement with ddPCR for estimation of H. contortus abundance (Spearman’s r = 0.77, p < 0.0001), although ddPCR demonstrated lower variability and greater sensitivity for the detection and quantification of H. contortus, particularly at low infection intensities.
Following a single treatment, IVM achieved >99% efficacy against all evaluated parasite groups throughout the monitoring period. In contrast, FBZ showed progressively reduced efficacy, particularly against trichostrongyles, H. contortus, and Strongyloides spp., indicating established benzimidazole resistance within the studied flock.
Overall, the findings demonstrate that OC provides a rapid and practically useful tool for flock-level parasite monitoring, while ddPCR remains the most analytically sensitive method for species-specific detection and confirmation of low-intensity infections. The combined application of AI-assisted microscopy and molecular
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diagnostics may therefore support more evidence-based and sustainable parasite-control strategies in sheep production systems.