Rachprakhon Phuphitchan, Purivirojkul Watchariya
Animal Systematics and Ecology Speciality Research Unit (ASESRU), Department of Zoology, Faculty of Science, Kasetsart University, Bang Khen Campus, Bangkok 10900, Thailand.
Biodiversity Center Kasetsart University (BDCKU), Bangkok 10900, Thailand.
Parasites Hosts Dis. 2024 Nov;62(4):461-475. doi: 10.3347/PHD.24033. Epub 2024 Nov 22.
This study aimed to investigate the infection status and species diversity of trematode cercariae in freshwater snails from canal networks in the Bangkok Metropolitan Region (BMR), Thailand. The snails were collected from 35 sites during 2 cycles of the wet (July-October) and dry (November-June) seasons in 2018-2019. A total of 29,420 snails representing 24 species/subspecies were examined for cercarial infection using shedding and crushing techniques. We found that 1,275 snails from 12 species/subspecies were infected, resulting in an overall prevalence of 4.3%. Infections were significantly higher (p<0.001) during the wet season (5.9%; 970/16,473) than during the dry season (2.4%; 305/12,947). Morphological identification revealed 37 distinct types within 15 morphotypes, with the armatae morphotype showing the highest infection rate (1.8%) and the greatest cercarial diversity (8 distinct types). This study highlights the health risk posed by the Bithynia siamensis siamensis, which was the second most prevalent (8.5%) and hosted the greatest cercarial diversity (11 morphotypes, 15 distinct types). This subspecies also displayed a wide distribution range (31 localities) with a generally high occurrence frequency in the BMR. This study firstly documents a gymnophallid digenean as a freshwater digenean, presenting evidence of a dichotoma cercarial morphotype from 4 species/subspecies (Filopaludina martensi martensi, F. sumatrensis polygramma, B. siamensis siamensis, and Wattebledia siamensis) with a low infection range (0.1-0.4%). A staggering diversity of cercariae was observed in the BMR canal networks with seasonal fluctuations. The B. siamensis siamensis displayed notable epidemiological importance in the BMR flowing-water networks. This study provides quantitative and qualitative morphological descriptions and measurement guidelines for the dichotoma cercaria in Thailand.
本研究旨在调查泰国曼谷大都市区（BMR）运河网络淡水螺体内吸虫尾蚴的感染状况和种类多样性。在2018 - 2019年的湿季（7月至10月）和干季（11月至6月）的两个周期内，从35个地点采集了螺类。使用逸出法和压碎法对总共代表24个物种/亚种的29,420只螺进行了尾蚴感染检测。我们发现，来自12个物种/亚种的1,275只螺受到感染，总体感染率为4.3%。湿季（5.9%；970/16,473）的感染率显著高于干季（2.4%；305/12,947）（p<0.001）。形态学鉴定揭示了15个形态类型中的37种不同类型，其中armatae形态类型的感染率最高（1.8%），尾蚴多样性最大（8种不同类型）。本研究突出了暹罗双脐螺（Bithynia siamensis siamensis）所带来的健康风险，它是第二常见的（8.5%），且尾蚴多样性最大（11个形态类型，15种不同类型）。该亚种分布范围也很广（31个地点），在BMR地区的出现频率普遍较高。本研究首次记录了一种裸茎类复殖吸虫作为淡水复殖吸虫，提供了来自4个物种/亚种（马氏沼螺（Filopaludina martensi martensi）、多纹沼螺（F. sumatrensis polygramma）、暹罗双脐螺和暹罗瓦氏螺（Wattebledia siamensis））的二歧尾蚴形态类型的证据，感染范围较低（0.1 - 0.4%）。在BMR运河网络中观察到了惊人的尾蚴多样性以及季节性波动。暹罗双脐螺在BMR流水网络中显示出显著的流行病学重要性。本研究为泰国的二歧尾蚴提供了定量和定性的形态学描述及测量指南。
