Isolation and purification of Fasciola hepatica eggs

The present egg isolation method is both a rapid and simple technique for recovering large numbers of Fasciola hepatica eggs (1 X 10(7) eggs/gradient) from bovine bile. Bile from infected cattle was first passed through a 45 micron screen sieve. The F. hepatica eggs were collected from the surface of the screen by backwashing with a jet of distilled water. The resultant egg suspension was layered on a 60% to 100% (v/v) linear Percoll gradient prepared in distilled water. Centrifugation at 450 g for 20 min resulted in the formation of 2 visible bands and a pellet. The top band (density of 1.075 g ml-1) contained viscous debris and crystallized bile pigments. The second visible band (density of 1.093-1.099 g ml-1) consisted of a relatively pure population of F. hepatica eggs (greater than 93%) while the pellet contained only F. hepatica egg shells.