Eastern and Southern Africa Centre of International Parasite Control, Kenya Medical Research Institute (KEMRI), P.O. Box 54840 - 00200, Nairobi, Kenya.
BMC Public Health. 2018 Apr 11;18(1):478. doi: 10.1186/s12889-018-5414-9.
Kato-Katz technique has been the mainstay test in Schistosoma mansoni diagnosis in endemic areas. However, recent studies have documented its poor sensitivity in evaluating Schistosoma mansoni infection especially in areas with lower rates of transmission. It's the primary diagnostic tool in monitoring impact of the Kenya national school based deworming program on infection transmission, but there is need to consider a more sensitive technique as the prevalence reduces. Therefore, this study explored the relationship between results of the stool-based Kato-Katz technique with urine-based point-of-care circulating cathodic antigen (POC-CCA) test in view to inform decision-making by the program in changing from Kato-Katz to POC-CCA test.
We used two cross-sectional surveys conducted pre- and post- mass drug administration (MDA) using praziquantel in a representative random sample of children from 18 schools across 11 counties. A total of 1944 children were randomly sampled for the study. Stool and urine samples were tested for S. mansoni infection using Kato-Katz and POC-CCA methods, respectively. S. mansoni prevalence using each technique was calculated and 95% confidence intervals obtained using binomial regression model. Specificity (Sp) and sensitivity (Sn) were determined using 2 × 2 contingency tables and compared using the McNemar's chi-square test.
A total of 1899 and 1878 children were surveyed at pre- and post-treatment respectively. S. mansoni infection prevalence was 26.5 and 21.4% during pre- and post-treatment respectively using POC-CCA test, and 4.9 and 1.5% for pre- and post-treatment respectively using Kato-Katz technique. Taking POC-CCA as the gold standard, Kato-Katz was found to have significantly lower sensitivity both at pre- and post-treatment, Sn = 12.5% and Sn = 5.2% respectively, McNemar test χ = 782.0, p < 0.001. In overall, the results showed a slight/poor agreement between the two methods, kappa index (k) = 0.11, p < 0.001, inter-rater agreement = 77.1%.
Results showed POC-CCA technique as an effective, sensitive and accurate screening tool for Schistosoma mansoni infection in areas of low prevalence. It was up to 14-fold accurate than Kato-Katz which had extremely inadequate sensitivity. We recommend usage of POC-CCA alongside Kato-Katz examinations by Schistosomiasis control programs in low prevalence areas.
加藤厚涂片法一直是曼氏血吸虫病诊断的主要检测方法。然而，最近的研究表明，在传播率较低的地区，该方法检测曼氏血吸虫病感染的灵敏度较差。它是监测肯尼亚国家学校驱虫项目对感染传播影响的主要诊断工具，但随着患病率的降低，需要考虑更敏感的技术。因此，本研究探讨了粪便加藤厚涂片法与尿液即时检测循环阴离子抗原（POC-CCA）检测结果之间的关系，以便为该项目从加藤厚涂片法向 POC-CCA 法转变提供决策依据。
我们使用了两种横断面调查，分别在 11 个县的 18 所学校的代表性随机儿童样本中进行了大规模药物治疗（MDA）前后的调查。共有 1944 名儿童被随机抽样进行研究。使用加藤厚涂片法和 POC-CCA 法分别检测粪便和尿液样本中的曼氏血吸虫感染。用二项回归模型计算两种方法检测的曼氏血吸虫病患病率，并获得 95%置信区间。使用 2×2 列联表确定特异性（Sp）和敏感性（Sn），并使用 McNemar 的卡方检验进行比较。
MDA 前后分别有 1899 和 1878 名儿童接受了调查。用 POC-CCA 检测，MDA 前后曼氏血吸虫病感染率分别为 26.5%和 21.4%，用加藤厚涂片法检测，MDA 前后分别为 4.9%和 1.5%。以 POC-CCA 为金标准，加藤厚涂片法在 MDA 前后的灵敏度均明显较低，Sn 分别为 12.5%和 5.2%，McNemar 检验 χ²=782.0，p<0.001。总的来说，两种方法的结果显示出轻微/较差的一致性，kappa 指数（k）=0.11，p<0.001，观察者间一致性=77.1%。
结果表明，POC-CCA 技术是一种有效的、敏感的、准确的低流行地区曼氏血吸虫病筛查工具。其准确性比加藤厚涂片法高 14 倍，加藤厚涂片法的灵敏度极低。我们建议在低流行地区，血吸虫病控制项目应将 POC-CCA 与加藤厚涂片法结合使用。
