The coprological diagnosis of gastrointestinal nematode infections in small ruminants

Infections with gastrointestinal nematodes (GIN) continue to represent a serious challenge to the health, welfare and productivity of grazing ruminants throughout the world. However, implementation in research, diagnosis and surveillance of these parasites is still poor. The present thesis provided novel insights into the coprological diagnosis of GIN infections in small ruminants with particular emphasis on the significance, interpretation and limitations of different faecal egg count (FEC) techniques and the faecal egg count reduction test (FECRT). The literature review provides an in-depth analysis of FEC/FECRT, considering also their limitations and gaps. These aspects have important implications towards the achievement of a proper diagnosis of GIN in small ruminants, particularly when FEC/FECRT are used in epidemiological surveys, anthelmintic drug efficacy studies and monitoring of control programs. The calibration and performance of different FEC techniques and the effect of different faecal preservation methods on GIN egg counts was assessed under field conditions in southern Italy. FLOTAC, saturated sodium chloride, and vacuum packing at +4°C resulted the most accurate FEC technique, flotation solution and preservation method, respectively, for reliable GIN egg counts in sheep. A longitudinal study of GIN egg counts was conducted on naturally infected dairy goats to evaluate the effects of the hour of sample collection on FECs and the relationship between FECs and worm burden. The results indicated no significant difference in FECs within 24h, but they showed a significant difference across the 14 months. There was also a significant correlation between FECs and GIN worm burden in particular regarding Haemonchus contortus. A further field study was conducted to evaluate the efficacy of anthelminthic drugs against GIN in small ruminants in southern Italy by means of three FECR formulae that mainly differ whether a control group was included. The efficacy was evaluated for 4 anthelminthics (levamisole, ivermectin, moxidectin and monepantel). A reduced efficacy was claimed when FECR was 99%) and LCLs were generally high (>90%) for all the anthelminthic drugs regardless of the formula. Easy methods for FECRT (without control groups) are suggested. The value of pooled faecal samples for FEC and FECR of GIN was assessed in 10 sheep farms in southern Italy. We also verified whether the accuracy was affected by pool size (5, 10 and 20 individual samples) and analytic sensitivity (10, 15 and 50 EPG) of the FEC technique. GIN FECs of pooled samples correlated positively with mean FECs of individual samples, with very high correlation coefficients (ranging from 0.94 to 0.99) across the 3 different pool sizes and analytic sensitivities. Pooling faecal samples using the Mini-FLOTAC technique holds promise as a valid strategy for assessing FECs and FECR of GIN in small ruminants. Finally, the present assessments and future perspectives of FEC/FECR techniques are discussed with particular focus on their application for the detection of anthelmintic resistance and as indicator of targeted (selective) treatments. Promoting FEC/FECR among practitioners and farmers is one of the priority areas for an integrated parasite management. However, novel solutions are needed to reduce workload/cost and to encourage uptake of FEC/FECRT by veterinary practitioners and small ruminant farmers. Together with the strategy of performing FEC/FECR on pooled faecal samples, one of the challenges of copromicroscopy in small ruminants is to perform diagnosis of GIN directly on the farm by using field portable kits