The effect of assay conditions on the recovery of schistosomula from the lungs of normal and resistant rats infected with Schistosoma mansoni.

The recovery of schistosomula from lungs of normal and resistant Sprague-Dawley and Fischer rats was analyzed by varying the assay conditions. The effects of incubation medium, incubation time, and perfusion procedure on yields of schistosomula were significant and additive. Optimal assay conditions were established to recover schistosomula by the lung recovery assay. Differences were observed in the number of schistosomula recovered from lungs of normal and resistant rats; the assay was performed as a function of time after challenge infection. Differences in schistosomula recovered were significant on days 3 to 5 (Fischer) and days 3 to 6 (Sprague-Dawley); afterwards, no differences were observed in recoveries of schistosomula from lungs. Interpretations of these findings are disscused.