Advancing gastrointestinal parasite diagnosis in West African long-legged lambs in Southern Benin: a comparative study of McMaster and Mini-FLOTAC methods

Abstract

Gastrointestinal (GI) parasites remain a significant global challenge to livestock health and farm productivity, particularly in resource-limited regions. Accurate and reliable fecal egg count (FEC) methods are essential for quantifying parasite burden and evaluating anthelmintic efficacy. This study compared the diagnostic performance of the Mini-FLOTAC and the modified McMaster techniques for detecting GI parasites in West African Long-legged (WALL) sheep under field conditions in southern Benin. A cross-sectional survey was conducted, during which 200 fresh fecal samples were collected from four-month-old lambs across five representative sheep farms. Each sample was divided and analyzed in parallel using the Mini-FLOTAC (using 2 g of feces diluted in a 1:10 ratio with saturated sodium chloride solution) and the modified McMaster technique (using 3 g of feces in a 1:15 dilution). Diagnostic parameters, including the intensity of infection expressed as eggs/oocysts per gram of feces (EPG/OPG, respectively), the prevalence, and the precision, were statistically analyzed and compared. Method agreement was assessed using Cohen’s kappa coefficient. The Mini-FLOTAC technique demonstrated superior performance, detecting a broader spectrum of parasites, including Nematodirus spp., Marshallagia spp., and Moniezia spp., which were frequently undetected by McMaster. Agreement between techniques was high for strongylids and Eimeria spp. (κ ≥ 0.76), but poor for other taxa (κ < 0.30). Mini-FLOTAC recorded significantly higher FECs and oocyst per gram of feces (OPG) values across farms (p < 0.05), and consistently exhibited greater diagnostic precision, with lower coefficients of variation (CVs ranging from 12.37% to 18.94%) and higher reproducibility (> 80% precision). Misclassification analysis revealed that the McMaster method underdiagnosed up to 12.5% of infections, especially for low-shedding species. These findings highlight Mini-FLOTAC as a more sensitive, precise, and operationally robust tool for GI parasite surveillance in small ruminants. Its adoption can improve the reliability of epidemiological monitoring and support sustainable parasite control programs in resource-limited settings.