Development of patent Ascaris suum infections in pigs following intravenous administration of larvae hatched in vitro

The normal tissue migration of Ascaris suum in the pig host involves larval development in the liver accompanied by considerable pathological changes. The vast majority of larvae that reach the small intestine are later expel led by unknown mechanisms. We show that when migration through the liver is bypassed by inoculation of pigs with an intravenous dose of larvae hatched in vitro, the larvae not only complete migration and return to the small i ntestine, but they also seem to have a greater chance of survival to adulth ood. This technique offers new possibilities for studies on specific lung i nvolvement in protective immunity, provides valuable information for the un derstanding of self cure by larval expulsion, and adds to our understanding of the evolution of migration of Ascaris larvae in tissues.