Comparison of Schistosoma mansoni migration patterns in normal and irradiated cercaria-immunized mice by means of autoradiographic analysis. Evidence that worm elimination occurs after the skin phase in immunized mice.

Migration and elimination of radiolabeled Schistosoma mansoni were compared in naive and irradiated cercaria-immunized mice by autoradiography of compressed host tissues. The results indicated that 1) most of the normal elimination of schistosomula in unimmunized mice and the additional elimination in immunized mice occur at some point(s) after arrival of schistosomula in the lungs and before their development into adult worms, 2) migration of schistosomula from skin to lungs is delayed for several days but not reduced in immunized mice, 3) migration of schistosomula from lungs to liver is delayed for several days in immunized mice, and 4) schistosomula reach the liver in reduced numbers or are killed and cleared in the liver in greater numbers in immunized mice. The lung chop procedure was shown to recover schistosomula from control and irradiated cercaria-immunized mice with equal efficiency. Autoradiography of all tissues of the body demonstrated that, in both control and immunized mice, at least 20-25% of the schistosomula detectable 2 and 3 weeks after infection were present in tissues other than the skin, lungs and liver.