Attempts to transfer immunity to Trichobilharzia ocellata (Trematoda: Schistosomatidae) passively via lymphoid cells and/or serum.

White Pekin ducklings were injected with serum, lymphoid cells, or both, derived from donor birds which were immune to reinfection by the schistosome trematode, Trichobilharzia ocellata. Ducklings receiving serum and/or cells from susceptible birds, and untreated ducklings, served as controls. One set of experimental and control ducklings was kept alive and all of these birds passed viable T. ocellata eggs by day 20 indicating that protective immunity had not been transferred. Another set was killed 3-5 days after exposure. The schistosomula which were recovered from these were measured and in most cases no difference between experimentals and controls could be seen. However, birds which had received the maximum dose of serum (8 ml.) did produce worms of different length, the immune serum recipients having shorter parasites than controls. A second experiment was performed in which up to 60 ml. of immune serum was injected, controls being recipients of normal serum or saline. Recipients of immune serum either failed to pass worm eggs entirely, or passed low numbers after delayed onset. Controls were variable but exhibited earlier patency and heavier infections. Schistosomula recovered from birds killed 4 days after exposure were measured. In 3 of 4 groups, experimentals were significantly shorter than controls, but no significant differences were detected between normal serum and saline controls.