The monitoring of gastrointestinal nematodes and anthelmintic resistance and its implementation in small ruminant farms of Northern Italy

Gastrointestinal nematodes (GIN) pose a significant challenge to the health and productivity of sheep and goats worldwide. Anthelmintic drugs have historically been the primary strategy for managing GIN infections, but this approach has led to the emergence and spread of anthelmintic resistance (AR), threatening the sustainability of small ruminant farming. This thesis addressed the growing concern of AR in small ruminant farms in Northern Italy, a region characterized by diverse farming practices. The project was organized around two main aims: i) improving AR monitoring by exploring practical solutions; ii) building knowledge on the status of AR in North-eastern Italy, where studies on GIN and AR are still lacking. Firstly, an in-depth review of the epidemiology and control of GIN infections in Italy was conducted to summarize the knowledge on the issue and to examine the existing control measures, pointing out their limitations and the gaps in current knowledge. Secondly, the research investigated the potential of using pooled faecal samples as a cost-effective alternative to individual analysis for both faecal egg counts (for GIN monitoring) and faecal egg count reduction tests (FECRT). The findings suggested that pooled sampling can reliably estimate GIN burden and treatment efficacy, though individual analyses remain strongly preferable for FECRT. The third part focused on promoting a genus-specific approach to FECRT, using coprocultures to differentiate between genera. By monitoring the response to treatment of each GIN genus, this study, carried out in two goat farms, enhanced the precision of AR diagnosis, improving the interpretation of FECRT results. The genusspecific approach was then applied in the fourth phase to assess the efficacy of anthelmintics in six sheep and six goat farms of North-Eastern Italy. This application provided insights into the current state of AR across different GIN genera, revealing high levels of treatment ineffectiveness, especially against Haemonchus contortus. Lastly, a novel real-time PCR assay was designed to quantify the relative presence of H. contortus eggs among the overall GIN egg population. This assay was tested during FECRT trials conducted in five sheep and five goat farms, demonstrating greater specificity in monitoring GIN infections. The real-time PCR assay showed strong potential for integration into routine AR monitoring, providing more accurate diagnoses and enabling better-targeted interventions. Overall, this thesis provides valuable contributions to the understanding and monitoring of AR in Northern Italy, with broader implications for optimizing diagnostic practices. By promoting practical methods for AR monitoring, this thesis lays the groundwork for more effective and sustainable management practices.