Center for Evolutionary and Theoretical Immunology, Department of Biology, University of New Mexico, Albuquerque, NM, United States of America.
Parasitology Division, Museum of Southwestern Biology, Department of Biology, University of New Mexico, Albuquerque, NM, United States of America.
PLoS Negl Trop Dis. 2021 Mar 24;15(3):e0009175. doi: 10.1371/journal.pntd.0009175. eCollection 2021 Mar.
We were tasked by the World Health Organization (WHO) to address the following question: What techniques should be used to diagnose Schistosoma infections in snails and in the water in potential transmission sites? Our goal was to review and evaluate the available literature and provide recommendations and insights for the development of WHO's Guidelines Development Group for schistosomiasis control and elimination.
We searched several databases using strings of search terms, searched bibliographies of pertinent papers, and contacted investigators who have made contributions to this field. Our search covered from 1970 to Sept 2020. All papers were considered in a PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) framework, and retained papers were grouped by technique and subjected to our GRADE (Grading of Recommendations, Assessment, Development and Evaluations) evidence assessment profile determined in consultation with WHO. We also considered issues of sensitivity, specificity, coverage, cost, robustness, support needs, schistosome species discrimination, and relevant detection limits.
Our PRISMA process began with the perusal of 949 articles, of which 158 were retained for data extraction and evaluation. We identified 25 different techniques and for each applied a GRADE assessment considering limitations, inconsistency, imprecision, indirectness, and publication bias. We also provide advantages and disadvantages for each category of techniques.
Our GRADE analysis returned an assessment of moderate quality of evidence for environmental DNA (eDNA), qPCR and LAMP (Loop-mediated isothermal amplification). No single ideal diagnostic approach has yet been developed, but considerable recent progress has been made. We note a growing trend to use eDNA techniques to permit more efficient and replicable sampling. qPCR-based protocols for follow-up detection offer a versatile, mature, sensitive, and specific platform for diagnosis though centralized facilities will be required to favor standardization. Droplet digital PCR (ddPCR) can play a complementary role if inhibitors are a concern, or more sensitivity or quantification is needed. Snail collection, followed by shedding, is encouraged to provide specimens for sequence verifications of snails or schistosomes. LAMP or other isothermal detection techniques offer the prospect of less expensive and more distributed network of analysis but may face standardization and verification challenges related to actual sequences amplified. Ability to detect schistosome infections in snails or in the water is needed if control and elimination programs hope to succeed. Any diagnostic techniques used need to be regularly verified by the acquisition of DNA sequences to confirm that the detected targets are of the expected species. Further improvements may be necessary to identify the ideal schistosome or snail sequences to target for amplification. More field testing and standardization will be essential for long-term success.
我们受世界卫生组织（WHO）委托，回答以下问题：在潜在传播地点的螺和水中，应使用哪些技术来诊断血吸虫感染？我们的目标是回顾和评估现有文献，并为制定世卫组织血吸虫病控制和消除指南开发小组提供建议和见解。
我们使用搜索词字符串搜索了多个数据库，查阅了相关论文的参考文献，并联系了为本领域做出贡献的研究人员。我们的搜索涵盖了 1970 年至 2020 年 9 月。所有论文均在 PRISMA（系统评价和荟萃分析的首选报告项目）框架内进行考虑，并根据技术分组保留论文，并根据与世界卫生组织协商确定的我们的 GRADE（推荐评估、制定和评估的分级）证据评估情况进行评估。我们还考虑了敏感性、特异性、覆盖率、成本、稳健性、支持需求、血吸虫种属鉴别和相关检测限等问题。
我们的 PRISMA 流程首先浏览了 949 篇文章，其中 158 篇被保留用于数据提取和评估。我们确定了 25 种不同的技术，并为每种技术应用 GRADE 评估，考虑了局限性、不一致性、不精确性、间接性和出版偏倚。我们还为每个类别的技术提供了优缺点。
我们的 GRADE 分析对环境 DNA（eDNA）、qPCR 和 LAMP（环介导等温扩增）的证据质量评估为中等。尚未开发出单一的理想诊断方法，但最近取得了相当大的进展。我们注意到，使用 eDNA 技术来提高采样效率和可重复性的趋势日益明显。基于 qPCR 的后续检测方案为诊断提供了一种通用、成熟、敏感和特异的平台，但需要集中设施来促进标准化。如果存在抑制剂问题，或需要更高的灵敏度或定量，则可以发挥数字 PCR（ddPCR）的互补作用。LAMP 或其他等温检测技术有望提供更经济、更分布式的分析网络，但可能面临与实际扩增序列相关的标准化和验证挑战。如果控制和消除规划希望取得成功，就需要能够检测螺或水中的血吸虫感染。任何使用的诊断技术都需要通过获取 DNA 序列进行定期验证，以确认检测到的靶标是预期的物种。进一步的改进可能是必要的，以确定理想的血吸虫或螺序列进行扩增。更多的现场测试和标准化对于长期成功至关重要。
