Principal Investigator: Manigandan Lejeune

Co-PI: Doug Antczak, Dwight Bowman, Sabine Mann

DESCRIPTION (provided by applicant): 

Parasite control strategies such as blanket treatment of all horses in a herd and/or interval treatment regimen have resulted in the fast emergence of equine strongyles resistance to all major classes of drugs on the market. In this regard, the guidelines set by the American Association of Equine Practitioners (AAEP) advocate for evidence-based strongyle control by recommending targeted treatment of heavy egg shedders while low shedders are left untreated to maintain susceptible parasite refugia. As 50-75% of adult horses in a herd are low shedders, preventing them from unnecessary anthelmintic exposure is critical to tackle resistance. There are various fecal egg count (FEC) techniques in use, but none is identified as a gold standard and methods comparison studies are lacking. We hypothesize that the diagnostic performance of FEC methodologies differs and the results of various quantitation methods can be standardized to obtain a closer to accurate estimate. Firstly, we aim to identify the gold standard test by performing methods comparison studies using polystyrene beads, which have comparable specific gravity of strongyle eggs, as proxy. The linear fit of 12 commonly used FEC methodologies will be studied using bead standards in the clinically applicable range (63 to 1,000) to determine their suitability for FEC. Deming regression analysis will identify the gold standard test. Secondly, we will determine the correction factor termed the Coefficient of Quantitation (CoQ) for each of the linear fit tests, in comparison to the gold standard. CoQ can be applied to any given FEC to obtain an accurate estimate which eventually negates the dependence for a gold standard test. Finally, the validity of CoQ for each of the 12 FEC methods will be analyzed using 100 different horse fecal samples. Overall, this study will standardize routine FEC tests and promote uniformity in implementing AAEP parasite control guidelines.