Objective: To study the impact of environmental temperature on the development of Schistosoma japonicum larvae within the Oncomelania hupensis.
Methods: Oncomelania snails, collected from the field and free of S. japonicum infection, were exposed to miracidiae of S. japonicum in a ratio of 1:20 and raised at 30 degrees C, 27 degrees C, 24 degrees C, 21 degrees C and 18 degrees C, respectively. The prepatent period of larvae within the Oncomelania hupensis and the developmental velocity were determined, of which the relationship with the temperature was analysed.
Results: The average prepatent period of cercariae in snail was (128.89 +/- 16.05) d, (95.00 +/- 21.03) d, (71.93 +/- 12.74) d and (62.74 +/- 14.19) d at 21 degrees C, 24 degrees C, 27 degrees C, 30 degrees C, respectively. The regression formulation between prepatent period and temperature was y = 730.68x(-0.8918) (r = 0.9976, P < 0.01). And the regression formulation between developmental velocity of S. japonicum larvae in snail and temperature was y = 0.0235ln(x) -0.0639 (r = 0.9973, P < 0.01). It was derived that the unitial temperature for the development of S. japonicum within the snails was 15.17 degrees C +/- 0.43 degree C.
Conclusion: The development of S. japonicum larvae within the Oncomelania snails declines with the decrease of temperature.