Caron Yannick, Celi-Erazo Maritza, Hurtrez-Boussès Sylvie, Lounnas Mannon, Pointier Jean-Pierre, Saegerman Claude, Losson Bertrand, Benítez-Ortíz Washington
Parasitology and Pathology of Parasitic Diseases, Fundamental and Applied Research for Animals & Health (FARAH), Faculty of Veterinary Medicine, University of Liège, Quartier Vallée 2, 6 Avenue de Cureghem, 4000 Liège, Belgium.
International Center for Zoonosis, Day Hospital, Central University of Ecuador, PO Box 17-03-100 Quito, Ecuador.
Parasite. 2017;24:24. doi: 10.1051/parasite/2017026. Epub 2017 Jun 30.
Fasciolosis is a widely distributed disease in livestock in South America but knowledge about the epidemiology and the intermediate hosts is relatively scarce in Ecuador. For three months, lymnaeid snails were sampled (n = 1482) in Pichincha Province at two sites located in a highly endemic area. Snails were identified (based on morphology and ITS-2 sequences) and the infection status was established through microscopic dissection and a multiplex polymerase chain reaction (PCR)-based technique. Techniques based on morphology were not useful to accurately name the collected snail species. Comparison with available DNA sequences showed that a single snail species was collected, Galba schirazensis. Live rediae were observed in 1.75% (26/1482) and Fasciola sp. DNA was detected in 6% (89/1482) of collected snails. The COX-1 region permitted identification of the parasite as Fasciola hepatica. The relative sensitivity and specificity of the microscope study, compared to PCR results, were 25.84% and 99.78%, respectively. The mean size of the snails recorded positive for F. hepatica through crushing and microscopy was significantly higher than the mean size of negative snails, but there was no such difference in PCR-positive snails. The role of G. schirazensis as an intermediate host of F. hepatica in Ecuador is discussed and the hypothesis of an adaptation of the parasite to this invasive snail is proposed. For the first time, an epidemiological survey based on molecular biology-based techniques assessed the possible role of lymnaeid snails in the epidemiology of fasciolosis in Ecuador.
肝片吸虫病是南美洲家畜中广泛传播的一种疾病，但在厄瓜多尔，关于其流行病学和中间宿主的知识相对匮乏。在皮钦查省一个高度流行地区的两个地点，对椎实螺进行了为期三个月的采样（n = 1482）。通过形态学和ITS-2序列对螺类进行鉴定，并通过显微镜解剖和基于多重聚合酶链反应（PCR）的技术确定感染状况。基于形态学的技术对于准确鉴定所采集的螺类物种并无用处。与现有DNA序列进行比较表明，所采集的是单一螺类物种，即希拉真椎实螺（Galba schirazensis）。在1.75%（26/1482）的螺类中观察到活的雷蚴，在6%（89/1482）的采集螺类中检测到肝片吸虫属（Fasciola sp.）的DNA。COX-1区域可将该寄生虫鉴定为肝片吸虫（Fasciola hepatica）。与PCR结果相比，显微镜检查的相对灵敏度和特异性分别为25.84%和99.78%。通过压碎和显微镜检查记录为肝片吸虫阳性的螺类的平均大小显著高于阴性螺类，但PCR阳性螺类之间没有这种差异。讨论了希拉真椎实螺作为肝片吸虫在厄瓜多尔中间宿主的作用，并提出了该寄生虫适应这种入侵螺类的假说。首次基于分子生物学技术的流行病学调查评估了椎实螺在厄瓜多尔肝片吸虫病流行病学中的可能作用。
