Modification of the lung recovery assay for schistosomula and correlations with worm burdens in mice infected with Schistosoma mansoni.

The kinetics of recovery of schistosomula from the lungs of previously-unexposed CF1 mice were studied following infection with Schistosoma mansoni cercariae. Lung tissue fragments were incubated from 3 to 48 hr and the completeness of recovery of viable schistosomula was determined. The recovery of schistosomula from the lungs was shown to correlate closely with 7-week worm recoveries. With the additional incubation described, the lung recovery assay may provide a more defined indicator of protective immunity. Based on the data generated by these analyses, it is predicted that under these conditions schistosomula arrive in the lungs from 3 to 7 days after infection, and that they sojourn there for a 3-day period.