Evaluation of a double centrifugation technique for the detection ofAnoplocephalaeggs in horse faeces

Abstract

AbstractFaecal samples of 250 horses from farms with a known history of tapeworm infection were examined comparatively for cestode eggs using a double centrifugation/combined sedimentation–floatation technique. From each faecal sample, three 5 g and three 15 g subsamples were processed, each using either saturated NaCl solution, specific gravity (sp. g.) 1.2 [NaCl]; concentrated sugar solution, sp. g. 1.26 [sugar]; or concentrated ZnSO4solution, sp. g. 1.3 [ZnSO4] for floatation. In total, faeces from 187 horses ( = 74.8%) tested ‘positive’ forAnoplocephalaeggs. Percentages of samples testing ‘positive’ forAnoplocephalaova were: 57.2% for 5 g faeces/NaCl, 66% for 15 g faeces/NaCl, 66% for 5 g faeces/sugar, 72.8% for 15 g faeces/sugar, 55.6% for 5 g faeces/ZnSO4, and 61.2% for 15 g faeces/ZnSO4, respectively. Processing of 15 g faecal samples resulted in a significant (P < 0.05; McNemar's χ2-test) increase in the percentage ofAnoplocephalaegg detection compared to processing of 5 g samples for all floatation solutions. By processing 15 g faecal samples using sugar solution for floatation, 97.3% of all samples that tested ‘positive’ forAnoplocephalaeggs were identified; there was no significant difference between the rate of samples that tested ‘positive’ using 15 g faeces/sugar (72.8%) and the total rate of samples that tested ‘positive’ (74.8%). Conversely, percentages of ‘positive’ samples from other test combinations were significantly (P < 0.0001, McNemar's χ2-test) lower than the total rate of samples testing ‘positive’. Processing faecal samples using sugar solution for floatation gave significantly (P < 0.05, Wilcoxon test) higherAnoplocephalaegg counts than using NaCl and ZnSO4solutions, for both 5 g and 15 g faecal samples. The double centrifugation technique using 15 g faecal samples and concentrated sugar solution for floatation appeared to offer an advantage for the detection ofAnoplocephalaeggs in horse faeces compared to the other test combinations.