Infectious and Tropical Diseases Research Group (e-INTRO), Biomedical Research Institute of Salamanca-Research Centre for Tropical Diseases at the University of Salamanca (IBSAL-CIETUS), Faculty of Pharmacy, University of Salamanca, Salamanca, Spain.
Hospital Nossa Senhora da Paz, Cubal, Angola.
Parasit Vectors. 2023 Oct 31;16(1):393. doi: 10.1186/s13071-023-06009-3.
Strongyloides stercoralis infection is a common neglected tropical disease distributed worldwide, mainly in tropical and subtropical climates. The impact of S. stercoralis infections on human health ranges from mild asymptomatic infections to chronic strongyloidiasis unnoticeable until the host is immunosuppressed. In severe strongyloidiasis, a syndrome of hyperinfection and larval dissemination to various organs can occur with high mortality rates. The diagnosis of strongyloidiasis is challenging because of the absence of a single standard reference test with high sensitivity and specificity, which also makes it difficult to estimate the accuracy of other diagnostic tests. This study aimed to evaluate, for the first time, the use of an easy-to-perform loop-mediated isothermal amplification (LAMP) colorimetric assay (named Strong-LAMP) for the molecular screening of strongyloidiasis in stool samples from patients in a low-resource endemic area in Cubal, Angola. To compare different LAMP application scenarios, the performance of the Strong-LAMP under field conditions in Angola was reassessed in a well-equipped reference laboratory in Spain and compared with a quantitative polymerase chain reaction (qPCR) method.
A total of 192 stool samples were collected from adult population in Cubal, Angola, and examined by parasitological methods (direct saline microscopy and Baermann's technique). DNA was extracted from each stool sample using a commercial kit and tested by the colorimetric Strong-LAMP assay for the detection of Strongyloides spp. under field conditions. Furthermore, all samples were shipped to a well-equipped laboratory in Spain, reanalysed by the same procedure and compared with a qPCR method. The overall results after testing were compared.
Strongyloides stercoralis larvae were identified by direct saline microscopy and Baermann in a total of 10/192 (5.2%) and 18/192 (9.4%) stool samples, respectively. Other helminth and protozoan species were also identified. The Strong-LAMP-positive results were visually detected in 69/192 (35.9%) stool samples. The comparison of Strong-LAMP results in field conditions and at a reference laboratory matched in a total of 146/192 (76.0%) samples. A total of 24/192 (12.5%) stool samples tested positive by qPCR.
This is the first study in which colorimetric Strong-LAMP has been clinically evaluated in a resource-poor strongyloidiasis endemic area. Strong-LAMP has been shown to be more effective in screening for strongyloidiasis than parasitological methods under field conditions and qPCR in the laboratory. Our Strong-LAMP has proven to be a field-friendly and highly accurate molecular test for the diagnosis of strongyloidiasis.
粪类圆线虫感染是一种常见的被忽视的热带病，分布于世界各地，主要在热带和亚热带气候中。粪类圆线虫感染对人类健康的影响范围从轻度无症状感染到慢性粪类圆线虫病，直到宿主免疫抑制时才会显现。在严重的粪类圆线虫病中，可能会发生幼虫过度感染和向各种器官传播的综合征，死亡率很高。由于缺乏具有高灵敏度和特异性的单一标准参考检测方法，粪类圆线虫病的诊断具有挑战性，这也使得难以估计其他诊断检测方法的准确性。本研究首次评估了一种易于操作的环介导等温扩增（LAMP）比色检测法（命名为 Strong-LAMP）在安哥拉 Cubal 资源匮乏的流行地区患者粪便样本中进行粪类圆线虫病分子筛查的效果。为了比较不同的 LAMP 应用场景，我们在西班牙的一个设备齐全的参考实验室中重新评估了 Strong-LAMP 在现场条件下的性能，并将其与定量聚合酶链反应（qPCR）方法进行了比较。
共收集了来自安哥拉 Cubal 成年人群的 192 份粪便样本，采用寄生虫学方法（直接盐水显微镜检查和巴氏法）进行检查。从每份粪便样本中提取 DNA，使用商业试剂盒进行检测，并在现场条件下通过比色 Strong-LAMP 检测法检测粪类圆线虫属。此外，所有样本均运往西班牙的一个设备齐全的实验室，按照相同的程序重新分析，并与 qPCR 方法进行比较。对所有检测结果进行了比较。
直接盐水显微镜检查和巴氏法共鉴定出 10/192（5.2%）和 18/192（9.4%）粪便样本中的粪类圆线虫幼虫。还鉴定了其他的蠕虫和原生动物物种。在 69/192（35.9%）粪便样本中通过肉眼观察到 Strong-LAMP 阳性结果。在现场条件下和参考实验室进行的 Strong-LAMP 结果比较在总共 146/192（76.0%）样本中匹配。24/192（12.5%）粪便样本通过 qPCR 检测呈阳性。
这是首次在资源匮乏的粪类圆线虫病流行地区对比色 Strong-LAMP 进行临床评估的研究。Strong-LAMP 已被证明在现场条件下比寄生虫学方法和实验室中的 qPCR 更有效地筛查粪类圆线虫病。我们的 Strong-LAMP 已被证明是一种适用于现场且高度准确的粪类圆线虫病诊断分子检测方法。
