Diab Radwa Galal, Tolba Mona Mohamed, Ghazala Rasha Abdelmawla, Abu-Sheasha Ghada Ahmed, Webster Bonnie L, Mady Rasha Fadly
Medical Parasitology Department, Faculty of Medicine, University of Alexandria, Egypt.
Parasitology Department, Medical Research Institute, University of Alexandria, Egypt.
Parasitol Int. 2021 Feb;80:102201. doi: 10.1016/j.parint.2020.102201. Epub 2020 Oct 1.
Intestinal schistosomiasis, one of the neglected tropical diseases whose control depends on accurate diagnosis of the disease prevalence. The use of low sensitive Kato Katz (KK) fecal egg detection method as a reference gold standard is not an accurate indication especially in low transmission areas. Latent class analysis frameworks especially the Bayesian could be used instead to compare between different diagnostic tests without the use of a gold standard method as a reference. Thus, this study compared two urine-based tests for the detection of circulating antigen and cell free DNA of Schistosoma mansoni versus KK method using the Bayesian latent class analytical framework and in two models where the trace results of point of contact - assay of circulating cathodic antigen (POC-CCA) were once estimated as positive, and as negative in the other model. The Bayesian framework in the trace CCA positive model showed an estimate of disease prevalence of 26% (95% BCI:0 to 60%). POC-CCA showed the highest sensitivity (74% with BCI: 9 to 91%) and lowest specificity for (20% with BCI: 0% to 37%) and the reverse for KK. For POC-CCA with traces considered negative, it was found that results between the three tests were moderated where the positivity for infection by Schistosoma antigen detection and PCR for cell free DNA approached that estimated by the Bayesian framework (44%), and the specificity for point of contact assay(81%; 95%BCI: 59% to 100%) rose in hand with its sensitivity(77%, 95% BCI:53% to 100%) and with results for PCR test (sensitivity = 80%; 95% BCI: 61% to 100%, specificity = 69%; 95% BIC: 47% to 100%). KK remains with the highest specificity while its sensitivity in the two models never exceeded 22%. Thus, we conclude that the use of a single urine sample could be very sensitive and highly specific in the diagnosis of intestinal schistosomiasis using either the trace negative model of point of contact assay, or conventional PCR, when compared to the fecal egg detection using duplicate KK. However, the use of a single tool restricts the management of the disease in areas of low endemicity.
肠道血吸虫病是一种被忽视的热带疾病，其防控依赖于对疾病流行率的准确诊断。使用低灵敏度的加藤厚涂片法（KK）作为粪便虫卵检测的参考金标准并不准确，尤其是在低传播地区。可以使用潜在类别分析框架，特别是贝叶斯分析框架，来比较不同的诊断测试，而无需使用金标准方法作为参考。因此，本研究使用贝叶斯潜在类别分析框架，在两个模型中比较了两种基于尿液的检测曼氏血吸虫循环抗原和游离DNA的测试与KK方法，在一个模型中，循环阴极抗原接触点检测（POC-CCA）的微量结果被估计为阳性，在另一个模型中则被估计为阴性。在微量CCA阳性模型中，贝叶斯框架显示疾病流行率估计为26%（95%贝叶斯可信区间：0至60%）。POC-CCA显示出最高的灵敏度（74%，贝叶斯可信区间：9%至91%）和最低的特异性（20%，贝叶斯可信区间：0%至37%），而KK则相反。对于微量结果被视为阴性的POC-CCA，发现三种测试之间的结果较为适中，其中曼氏血吸虫抗原检测和游离DNA的PCR检测的感染阳性率接近贝叶斯框架估计的水平（44%），接触点检测的特异性（81%；95%贝叶斯可信区间：59%至100%）随着其灵敏度（77%，95%贝叶斯可信区间：53%至100%）以及PCR测试结果（灵敏度 = 80%；95%贝叶斯可信区间：61%至100%，特异性 = 69%；95%贝叶斯信息准则：47%至100%）而提高。KK的特异性仍然最高，但其在两个模型中的灵敏度从未超过22%。因此，我们得出结论，与使用重复KK法进行粪便虫卵检测相比，使用单一尿液样本在使用接触点检测的微量阴性模型或传统PCR诊断肠道血吸虫病时可能非常敏感且具有高度特异性。然而，在低流行地区使用单一工具会限制疾病的管理。
