Effects of bile on the in vitro hatching, exsheathment, and migration of Ascaris suum larvae

This study reports on the in vitro egg hatching, exsheathment, migratory ac tivity, and sensitivity to anthelmintics of Ascaris suum larvae in cultures with or without bovine bile. Three methods for egg hatching and/or incubat ion were used: an object-glass method, a glass-bead method, and an incubati on method. An agar migration assay (AMA) was developed to test the migrator y activity of Ascaris larvae following hatching. Bile appeared to be an imp ortant stimulatory factor for both egg hatching and larval mobility in the incubation method. Incubation in low concentrations of bile (2%, 5%, or 10% ) stimulated both egg hatching and larval migration, whereas concentrations of at least 20% impaired egg hatching and larval migration. Furthermore, 5 % bile seemed to promote exsheathment of A. suum larvae.