Basic Medical College, Guangxi Traditional Chinese Medical University, Nanning, 530005, Guangxi, China.
College of Life Sciences, Inner Mongolia University, Hohhot, 010070, China.
Infect Dis Poverty. 2022 Aug 19;11(1):91. doi: 10.1186/s40249-022-01014-7.
Food-borne parasitic diseases decrease food safety and threaten public health. The snail species is an intermediate host for numerous human parasitic trematodes. Orientogalba ollula has been reported as intermediate hosts of many zoonotic trematodes. Here, we investigated the prevalence of zoonotic trematodes within O. ollula in Guangxi, China, and assessed their zoonotic potential.
Snails were collected from 54 sites in 9 cities throughout Guangxi. The snail and trematode larvae species were determined by combining morphological characteristics and molecular markers. The trematodes prevalence and constituent ratio were calculated and compared among different habitat environments. Phylogenetic trees of the trematode species were constructed using the neighbor-joining method with nuclear internal transcribed spacer 2 (ITS2) sequences. The developmental cycles of the isolated trematodes were examined by experimental infection in ducks. The developmental characteristics of Echinostoma revolutum was recorded by dissecting infected ducklings from 1-day post infection (dpi) to 10 dpi.
The overall prevalence of trematode larvae was 22.1% (1818/8238) in O. ollula from 11 sample sites. Morphological together with molecular identification, showed that E. revolutum, Australapatemon sp., Hypoderaeum conoideum, Pharyngostomum cordatum, and Echinostoma sp. parasitized O. ollula, with the highest infection rate of E. revolutum (13.0%). However, no Fasciola larvae were detected. The trematodes prevalence and constituent ratio varied in two sub-biotypes (P < 0.01). A neighbor-joining tree analysis of ITS2 sequences resulted in distinct monophyletic clades supported by sequences from isolated larvae with high bootstrap values. Ducklings exposed to O. ollula infected with Echinostoma sp., E. revolutum, and H. conoideum larvae were successfully infected. The animal model for Echinostoma revolutum was successfully established. E. revolutum matured from larvae to adult at 10 dpi in the intestine of the duck, and the developmental characteristics of E. revolutum were characterized by the maturation of the reproductive and digestive organs at 6-8 dpi.
This study revealed a high prevalence of zoonotic trematodes in O. ollula from Guangxi, China. Existing trematodes infection in animals and human clinical cases, coupled with the wide geographical distribution of O. ollula, necessitate further evaluations of the potential risk of spillover of zoonotic infection from animal to human and vice versa.
食源性寄生虫病降低了食品安全水平，威胁着公众健康。蜗牛是许多人类寄生吸虫的中间宿主。东方后圆田螺已被报道为许多人畜共患吸虫的中间宿主。在这里，我们调查了中国广西东方后圆田螺中寄生虫的流行情况，并评估了它们的人畜共患潜力。
从广西 9 个城市的 54 个地点采集蜗牛。通过结合形态特征和分子标记来确定蜗牛和吸虫幼虫的种类。计算并比较了不同生境环境中的吸虫感染率和构成比。采用核内转录间隔区 2（ITS2）序列的邻接法构建吸虫种的系统发育树。通过在鸭子中进行实验感染来检查分离吸虫的发育周期。从感染后 1 天（dpi）至 10 dpi 剖检感染雏鸭，记录棘口吸虫的发育特征。
在来自 11 个采样点的 8238 只东方后圆田螺中，吸虫幼虫的总感染率为 22.1%（1818/8238）。形态学和分子鉴定表明，棘口吸虫、南方后殖吸虫、片形肾口吸虫、有齿冠尾线虫和棘口科吸虫寄生在东方后圆田螺中，棘口吸虫的感染率最高（13.0%）。然而，未检测到片形吸虫幼虫。两种亚型的吸虫感染率和构成比存在差异（P < 0.01）。ITS2 序列的邻接法系统发育树分析产生了由分离幼虫的高支持率的序列组成的独特单系分支。暴露于感染棘口科吸虫、棘口吸虫和片形肾口吸虫的东方后圆田螺的雏鸭被成功感染。成功建立了棘口吸虫的动物模型。在鸭的肠道中，棘口吸虫从幼虫发育到成虫需要 10 天，棘口吸虫的发育特征表现为 6-8 天生殖和消化器官的成熟。
本研究揭示了中国广西东方后圆田螺中存在高流行的人畜共患吸虫。动物现有的吸虫感染和人类临床病例，加上东方后圆田螺广泛的地理分布，需要进一步评估动物向人类和人类向动物的人畜共患感染溢出的潜在风险。
