Institute of Ecology and Biological Resources (IEBR), Vietnam Academy of Science and Technology (VAST), Hanoi, Vietnam.
Graduate University of Science and Technology, Vietnam Academy of Science and Technology (VAST), Hanoi, Vietnam.
PLoS Negl Trop Dis. 2021 Jan 25;15(1):e0009093. doi: 10.1371/journal.pntd.0009093. eCollection 2021 Jan.
Two thiarid snail species, Melanoides tuberculata and Tarebia granifera have been reported as first intermediate hosts of the liver fluke Clonorchis sinensis; however, their role as true first intermediate hosts has not been verified. Thus, the present study aimed to clarify the suitability of these two snail species as first intermediate hosts of C. sinensis. This was accomplished by collecting snails from a highly endemic area for C. sinensis in Vietnam, the Thac Ba reservoir, and identifying shed cercariae using molecular techniques. We also conducted experimental infections of five snail species including M. tuberculata and T. granifera with eggs of C. sinensis.
METHODOLOGY/PRINCIPAL FINDINGS: A total of 11,985 snails, representing 10 species were sampled. Five snail species, M. tuberculata, T. granifera, Lymnaea swinhoei, Parafossarulus manchouricus, and Bithynia fuchsiana were found shedding cercariae with an overall prevalence of infection ranging from 0.7% to 11.5%. Seven cercarial types were recorded. Cercariae of C. sinensis were only found in Parafossarulus manchouricus. Using a multiplex PCR approach for detecting C. sinensis infection, the prevalence in P. manchouricus was 4.2%. Additionally, all five snail species were experimentally exposed to C. sinensis eggs, however only P. manchouricus was successfully infected with an infection rate of 7.87%.
CONCLUSIONS/SIGNIFICANCE: We confirmed that in the Thac Ba reservoir, Vietnam, the two thiarids, M. tuberculata and T. granifera are not suitable first intermediate hosts of C. sinensis. Only P. manchouricus was found infected by C. sinensis in nature, and was the only species that became infected experimentally.
两种拟钉螺，即斑拟钉螺和纹沼螺，已被报道为华支睾吸虫的第一中间宿主；然而，它们作为真正的第一中间宿主的角色尚未得到验证。因此，本研究旨在阐明这两种螺类作为华支睾吸虫第一中间宿主的适宜性。通过从越南华支睾吸虫高度流行地区的塔霸水库采集螺类，并使用分子技术鉴定脱落的尾蚴，完成了这一目标。我们还对包括斑拟钉螺和纹沼螺在内的五种螺类进行了华支睾吸虫卵的实验感染。
方法/主要发现：共采集了 11985 只螺类，代表 10 个种。发现有五种螺类，即斑拟钉螺、纹沼螺、中华圆田螺、朝鲜方格星虫和圆田螺，会脱落尾蚴，感染率在 0.7%到 11.5%之间。记录了七种尾蚴类型。只有朝鲜方格星虫中发现了华支睾吸虫的尾蚴。使用检测华支睾吸虫感染的多重 PCR 方法，在朝鲜方格星虫中的流行率为 4.2%。此外，所有五种螺类都进行了华支睾吸虫卵的实验暴露，但只有朝鲜方格星虫成功感染，感染率为 7.87%。
结论/意义：我们证实，在越南塔霸水库，两种拟钉螺，即斑拟钉螺和纹沼螺，不适合作为华支睾吸虫的第一中间宿主。只有朝鲜方格星虫在自然界中被华支睾吸虫感染，并且是唯一一种在实验中被感染的物种。
