Migration and growth of Neostrongylus linearis (Marotel, 1913) Gebauer, 1932 in sheep.

In order to establish the mammalian parasitic cycle of the nematode Neostrongylus linearis 18 lambs were infected with 5000 third-stage larvae obtained from the snail Cernuella (Xeromagna) cespitum arigonis. In the subsequent days, larvae were found in the walls of the caecum and colon, in the liver and the lungs, suggesting that the bloodstream is the main migratory route. The presence of low numbers of migrating larvae in the mesenteric lymph nodes indicates that this route is probably secondary. The first still sexually undifferentiated, fourth-stage larvae were found in the lungs on the 8th day post-infection (p.i.) and the first sexually differentiated fifth-stage larvae, on the 10th day. Also described are the macroscopic changes of the parasitized organs.