Autoradiographic analysis of Schistosoma mansoni migration from skin to lungs in naive mice. Evidence that most attrition occurs after the skin phase.

A study was performed to determine the extent of attrition of Schistosoma mansoni in naive mice (innate resistance) during the 1st week of infection. Each mouse was exposed to exactly 50 cercariae radiolabeled with [75Se] selenomethionine. On 1, 4, and 7 days postexposure, skin, lungs and liver were analyzed by compressed organ autoradiography for the presence of labeled larvae. Using this technique it was determined that no more than one-third of the 59% attrition that occurred between the cercarial and adult worm stages could be attributed to losses during the skin phase; most of the attrition in naive mice occurred after the migration of larvae to the lungs.