Bunchom Naruemon, Saijuntha Weerachai, Bounavong Virasack, Pakouakeu Bounmixay, Hansana Parita, Soundala Pheovaly, Jaroenchaiwattanachote Chavanut, Agatsuma Takeshi, Otake Sato Marcello, Buchy Philippe, Iwagami Moritoshi
Department of Tropical Medicine and Malaria, Research Institute, National Center for Global Health and Medicine, Tokyo, Japan.
SATREPS Project for Parasitic Diseases (JICA/AMED), Vientiane, Laos.
Trop Med Health. 2025 Apr 2;53(1):44. doi: 10.1186/s41182-025-00720-w.
Bithynia spp., a key intermediate host of Opisthorchis viverrini, is widely distributed in the lower Mekong sub-region, where opisthorchiasis remains a major public health concern. Understanding the genetic diversity and population structure of these snails is crucial for disease control. Bithynia siamensis sensu lato has been classified into three genetic lineages (I-III) based on cytochrome c oxidase subunit 1 (cox1) and 16S ribosomal RNA (16S rRNA) sequence analysis. This study focuses on Champasak Province, Laos, a highly endemic area of opisthorchiasis with limited genetic data on Bithynia spp.
Bithynia snails were collected from 12 villages in Khong and Mounlapamok districts, Champasak Province, Laos, between February and August 2024. To compare with previous reports, a total of 246 and 139 samples were analyzed using cox1 and 16S rRNA markers, respectively. Genetic diversity, genetic differentiation, and genetic structure were assessed based on these markers. Haplotype networks were constructed based on cox1 and 16S RNA sequences to elucidate the genetic lineage of these samples.
In the present study, only Bithynia siamensis goniomphalos was identified, while B. s. siamensis and B. funiculata were not found. Our findings revealed that both cox1 and 16S rRNA sequences exhibited high haplotype diversity among populations but relatively low nucleotide diversity. Two lineages of B. s. goniomphalos (lineages II and III) were detected in the studied areas, exhibiting significant genetic structuring among groups of snail populations from different villages in each lineage. Notably, lineage II was identified in Laos for the first time. The distribution of lineage II was observed near the southern border of Laos and Cambodia.
This study is the first to use DNA analysis to investigate Bithynia spp. in opisthorchiasis-endemic areas of Champasak Province, where B. s. goniomphalos lineages II and III were detected, but lineage I was not found. Our finding suggested that geographic or environmental factors influence the distribution of specific Bithynia lineages in this region. Many O. viverrini endemic areas in Southeast Asia still lack genetic data on Bithynia snails which could provide valuable insights into the transmission dynamics of opisthorchiasis. Therefore, further investigations should be conducted in these areas using cox1 and 16S rRNA sequences for comparison with previous studies.
比氏双脐螺是麝猫后睾吸虫的主要中间宿主，广泛分布于湄公河下游次区域，该地区后睾吸虫病仍是主要的公共卫生问题。了解这些螺类的遗传多样性和种群结构对疾病控制至关重要。基于细胞色素c氧化酶亚基1（cox1）和16S核糖体RNA（16S rRNA）序列分析，狭义暹罗比氏双脐螺已被分为三个遗传谱系（I - III）。本研究聚焦于老挝占巴塞省，这是后睾吸虫病的高流行区，但关于比氏双脐螺的遗传数据有限。
2024年2月至8月期间，从老挝占巴塞省孔县和孟拉帕莫克县的12个村庄收集比氏双脐螺。为与先前报告进行比较，分别使用cox1和16S rRNA标记对总共246个和139个样本进行分析。基于这些标记评估遗传多样性、遗传分化和遗传结构。基于cox1和16S RNA序列构建单倍型网络，以阐明这些样本的遗传谱系。
在本研究中，仅鉴定出暹罗比氏双脐螺指名亚种，未发现暹罗比氏双脐螺和有索比氏双脐螺。我们的研究结果表明，cox1和16S rRNA序列在种群间均表现出较高的单倍型多样性，但核苷酸多样性相对较低。在研究区域检测到暹罗比氏双脐螺指名亚种的两个谱系（谱系II和III），每个谱系中来自不同村庄的螺类种群组之间表现出显著的遗传结构。值得注意的是，谱系II首次在老挝被鉴定出来。在老挝和柬埔寨南部边境附近观察到谱系II的分布。
本研究首次利用DNA分析调查占巴塞省后睾吸虫病流行区的比氏双脐螺，在该地区检测到暹罗比氏双脐螺指名亚种的谱系II和III，但未发现谱系I。我们的研究结果表明，地理或环境因素影响该地区特定比氏双脐螺谱系的分布。东南亚许多麝猫后睾吸虫流行区仍缺乏比氏双脐螺的遗传数据，这些数据可为后睾吸虫病的传播动态提供有价值的见解。因此，应在这些地区进一步开展调查，使用cox1和16S rRNA序列与先前研究进行比较。
