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 activity, and sensitivity to anthelmintics of Ascaris suum larvae in cultures with or without bovine bile. Three methods for egg hatching and/or incubation were used: an object-glass method, a glass-bead method, and an incubation method. An agar migration assay (AMA) was developed to test the migratory activity of Ascaris larvae following hatching. Bile appeared to be an important 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.