RESUMEN
The Oncomelania hupensis snails were dually infected with Exorchis mupingensis and Schistosoma japonicum at different intervals for 21 d,37 d,55 d,70 d and 85 d.The results indicated that the development of all S.japonicum larvae were blocked in the snails of co-infection,and the complexity and number of secretions in and around all the wrecked S.japonicum larvae is proportional to the intervals of co-infection.In addition,we also described and compared the detailed change of snails' secretions in different conditions of infection,and determined that the snail's secretions may involve in the destruction and damage of S.japonicum larvae.The attack degrees on larval S.japonicum in O.hupensis snails dually infected by E.mupingensis and S.japonicum with longer intervals were stronger than that of shorter intervals,and snail haemo-lymphocytes numbers were more few in that of shorter intervals.But the secretions remarkably increased in more longer interval model experimental snail tissue.This finding may provide an alternative strategy for reducing and controlling the transmission of S.japonicum,and are very helpful for better understanding the host-parasite relationship.