Paller V G V, Kimura D, Uga S
Department of Parasitology, Faculty of Health Sciences, Kobe University School of Medicine, Kobe 654-0142, Japan.
J Parasitol. 2007 Apr;93(2):436-9. doi: 10.1645/GE-997R.1.
The infection dynamics of Centrocestus armatus cercariae with respect to second intermediate fish hosts were investigated using cercariae collected from naturally infected Semisulcospira libertina. Cercariae survival and infectivity were recorded at 2-hr intervals. Survival remained constant but decreased abruptly at 30 hr of age. An age-dependent model presented the best-fit curve for the survival data (r2 0.936), implying that cercariae tended to allocate resources equally among themselves and then died once those resources were depleted. Cercariae infectivity remained constant over the first 10 hr of life and then declined; an age-dependent model also provided a better fit (r2 = 0.956). The transmission rate of C. armatus cercariae to the fish host was relatively low near the time of emergence from the snail host but peaked at 85% after 1 hr and then maintained a plateau period until 5 hr of exposure to fish. The pattern of transmission was also investigated initially at varying densities of cercariae and then by maintaining a constant cercariae density but varying the total number. Results revealed that the pattern of transmission was frequency-dependent.
利用从自然感染的放逸短沟蜷中收集的尾蚴，研究了武装中殖吸虫尾蚴相对于第二中间宿主鱼类的感染动态。每隔2小时记录尾蚴的存活情况和感染力。存活率保持恒定，但在30小时龄时突然下降。一个年龄依赖性模型为存活数据呈现了最佳拟合曲线（r2 = 0.936），这意味着尾蚴倾向于在自身之间平均分配资源，一旦这些资源耗尽就会死亡。尾蚴的感染力在生命的前10小时保持恒定，然后下降；一个年龄依赖性模型也提供了更好的拟合（r2 = 0.956）。武装中殖吸虫尾蚴向鱼类宿主的传播率在从螺宿主逸出时相对较低，但在1小时后达到85%的峰值，然后在接触鱼类5小时之前保持平稳期。还首先在不同密度的尾蚴下研究了传播模式，然后通过保持尾蚴密度恒定但改变总数来进行研究。结果表明，传播模式是频率依赖性的。
