Faecal examination of Fasciola eggs fixed with formalin solution using the beads technique

Faecal examination for Fasciola eggs which were preserved in 5% and 10% formalin and TAF solutions for 6 years was carried out using the Beads technique. The morphological characters and the distinctive yellowish color of Fasciola eggs were retained and appeared similar to those of fresh eggs. The mean egg recovery rate of eggs in TAF solution was significantly lower than the others (P < 0.01). The egg recovery rates from 5% and 10% formalin samples were 57.2% and 60.8%, respectively, and these values were similar to the value of 58.8% for fresh Fasciola eggs in cattle faeces. For Paramphistomum eggs, preserved with 5% formalin, the mean egg recovery rate was 64.7%. Fasciola eggs and Paramphistomum eggs were easily identified by their morphological characters in this experiment. The present data demonstrated that preservation with 5% formalin solution is an acceptable means of storing faecal samples for later examination of Fasciola and Paramphistomum eggs using the Beads technique and presumably by other fluke sedimentation methods.