日本血吸虫幼虫在钉螺体内发育起点温度的研究

Initial Temperature for the Development of Schistosoma japonicum Larvae in Oncomelania hupensis

目的 研究环境温度对血吸虫幼虫在钉螺体内生长发育进程的影响程度。 方法 采集无血吸虫感染的钉螺 ,以钉螺与毛蚴 1∶2 0比例感染 ,感染后置于 3 0℃、2 7℃、2 4℃、2 1℃和 18℃环境中饲养 ,计算钉螺体内血吸虫的尾蚴开放前期和发育速度 ,分析尾蚴开放前期和发育速度与环境温度间的相关关系。 结果 2 1℃、2 4℃、2 7℃、3 0℃时血吸虫的尾蚴平均开放前期分别为 ( 12 8.89± 16.0 5 )d、( 95 .0 0± 2 1.0 3 )d、( 71.93± 12 .74)d和 ( 62 .74± 14 .19)d。尾蚴开放前期与环境温度的回归方程为 y =73 0 .68x-0 .8918(r =0 .9976,P <0 .0 1)。血吸虫发育速度与环境温度的回归方程为 y =0 .0 2 3 5ln(x) -0 .0 63 9(r =0 .9973 ,P <0 .0 1)。从此方程中推算出日本血吸虫幼虫在钉螺体内的发育起点温度为 15 .17℃± 0 .43℃。 结论 环境温度降低 ,钉螺体内血吸虫幼虫发育速度减慢。

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 ℃, 27 ℃, 24 ℃, 21 ℃ and 18 ℃, 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 ℃, 24 ℃, 27 ℃, 30 ℃, 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 ℃±0.43 ℃. Conclusion The development of S. japonicum larvae within the Oncomelania snails declines with the decrease of temperature.