A new PCR-based approach indicates the range of Clonorchis sinensis now extends to Central Thailand.
A new PCR-based approach indicates the range of Clonorchis sinensis now extends to Central Thailand.
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一种新的基于PCR的方法表明Clonorchis sinensis的范围现在延伸到泰国中部。
DOI：
10.1371/journal.pntd.0000367
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发表时间：
2009
影响因子：
3.8
通讯作者：
Thompson RC
中科院分区：
文献类型：
--
作者：
Traub RJ;Macaranas J;Mungthin M;Leelayoova S;Cribb T;Murrell KD;Thompson RC
从临床和流行病学的角度来看，区分属于后睾科、异睾科和Lecithodendrididae的鱼传吸虫是重要的，但由于卵在形态上相似，因此不可能使用传统的粪便学技术。因此，流行病学调查目前依赖于形态学检查成虫驱逐化疗。一个PCR测试能够扩增一段核糖体DNA的内转录间隔区的后睾吸虫和异卵吸虫卵直接从粪便中开发和评价在泰国中部的农村社区。结果表明，该方法能扩增出的最低DNA量分别为0.6pg、0.8pg和3pg。在实验条件下，PCR能够检测与上述种类的吸虫的混合感染。在泰国中部的Sanamchaikaet区的农村社区中，共有11.6%的人使用传统的寄生虫学检测技术对粪便中的“后睾吸虫样”卵呈阳性。与显微镜相比，PCR的敏感性和特异性分别为71.0%和76.7%。对镜检阳性PCR产物的分析表明，64%和23%的个体感染O。viverrini和C. sinensis，分别。其余13%（3个个体）被确定为双殖吸虫科的卵，推测是在摄入受感染鱼类后通过粪便机械传播的。本研究的一个直接发现是鉴定并首次报道了一种C.在泰国中部的一个地方性社区。这扩大了这种肝吸虫在东南亚的已知范围。本文开发的PCR为未来的流行病学调查提供了一个重要的工具，肝吸虫和肠吸虫物种的具体识别。据估计，目前全世界约有1 700万人感染鱼传吸虫。由鱼传播的肝吸虫（英语：Liver flukes），包括猫尾后殖吸虫（英语：Opisthrochis viverrini）和中华华支睾吸虫（英语：Clonelysis sinensis），可引起人类的肝脏和胆道疾病。微小肠吸虫广泛分布于东南亚，并日益被认为是与腹泻和胃炎相关的新兴病原体。本研究最重要的发现是发现并首次报道了一种C.泰国的一个特有群落。这一发现得到了一种新的基于PCR的技术的开发和应用的帮助，该技术能够特异性地检测和表征O。viverrini、C.中华吸虫和微小的肠吸虫，直接从粪便中的卵中获得。由于卵的形态相似，无法根据粪便的显微镜检查区分鱼传吸虫。该出版物还质疑了亚洲鱼传肝吸虫物种的分布与蜗牛中间宿主的分布密切平行的假设。PCR提供了一个有用的诊断工具，进一步大规模的流行病学调查将在东南亚进行，这将进一步阐明这些肝吸虫在人类和蜗牛中间宿主的分布，其优点是，可以进行更艰巨的驱虫冲洗确认的目标。
Differentiation of the fish-borne trematodes belonging to the Opisthorchiidae, Heterophyidae and Lecithodendriidae is important from a clinical and epidemiological perspective, yet it is impossible to do using conventional coprological techniques, as the eggs are morphologically similar. Epidemiological investigation therefore currently relies on morphological examination of adult worms following expulsion chemotherapy. A PCR test capable of amplifying a segment of the internal transcribed spacer region of ribosomal DNA for the opisthorchiid and heterophyid flukes eggs taken directly from faeces was developed and evaluated in a rural community in central Thailand. The lowest quantity of DNA that could be amplified from individual adults of Opisthorchis viverrini, Clonorchis sinensis and Haplorchis taichui was estimated at 0.6 pg, 0.8 pg and 3 pg, respectively. The PCR was capable of detecting mixed infection with the aforementioned species of flukes under experimental conditions. A total of 11.6% of individuals in rural communities in Sanamchaikaet district, central Thailand, were positive for ‘Opisthorchis-like’ eggs in their faeces using conventional parasitological detection techniques. In comparison to microscopy, the PCR yielded a sensitivity and specificity of 71.0% and 76.7%, respectively. Analysis of the microscopy-positive PCR products revealed 64% and 23% of individuals to be infected with O. viverrini and C. sinensis, respectively. The remaining 13% (three individuals) were identified as eggs of Didymozoidae, presumably being passed mechanically in the faeces following the ingestion of infected fishes. An immediate finding of this study is the identification and first report of a C. sinensis–endemic community in central Thailand. This extends the known range of this liver fluke in Southeast Asia. The PCR developed herein provides an important tool for the specific identification of liver and intestinal fluke species for future epidemiological surveys. It is estimated that approximately 17 million people are currently infected with fish-borne flukes worldwide. The fish-borne liver flukes Opisthrochis viverrini and Clonorchis sinensis cause hepatic and biliary disease in humans. The minute intestinal flukes are widely distributed in southeast Asia and are increasingly recognised as an emerging pathogen associated with diarrhoea and gastritis. The most significant finding of this study is the discovery and first report of a C. sinensis–endemic community in Thailand. This finding was aided by the development and application of a new PCR-based technique capable of specifically detecting and characterising O. viverrini, C. sinensis and the minute intestinal flukes, directly from eggs in faeces. Since the eggs are morphologically similar, the fish-borne flukes cannot be differentiated on basis of microscopic examination of stool. This publication also questions the presumption that the distribution of fish-borne liver fluke species in Asia closely parallels the distribution of the snail intermediate hosts. The PCR provides a useful diagnostic tool for further large-scale epidemiological surveys to be carried out in Southeast Asia, which will shed further light on the distribution of these liver flukes in human and snail intermediate hosts with the advantage that targets for more arduous anthelmintic flushing confirmations can be carried out.
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