Lawford Harriet L S, Sartorius Benn, Mayfield Helen J, Sam Filipina Amosa-Lei, Viali Satupaitea, Kamu Tito, Thomsen Robert, Lau Colleen L
UQ Centre for Clinical Research, Faculty of Health, Medicine, and Behavioural Sciences, The University of Queensland, Brisbane, Queensland, Australia.
National University of Samoa, Apia, Samoa.
PLoS Negl Trop Dis. 2025 Jan 30;19(1):e0012835. doi: 10.1371/journal.pntd.0012835. eCollection 2025 Jan.
Sensitive diagnostic tools that signal lymphatic filariasis (LF) transmission are needed to monitor the progress of LF elimination programs. Anti-filarial antibody (Ab) markers could be more sensitive than antigen (Ag) point-of-care tests for monitoring LF transmission in some settings. This study aimed to investigate the sensitivity of anti-filarial Abs for detecting signals of LF transmission in Samoa by i) investigating the sensitivity and specificity of Ab to identify Ag-positives; ii) estimating the average number needed to test (NNTestav) to identify LF-seropositives (seropositive for Ag and/or any Ab), and iii) compare the efficiency of the different serological indicators by target age group and sampling design.
A community-based serological survey of participants aged ≥5 years was conducted 1.5-3.5 months following the first round of triple-drug mass drug administration in Samoa in 2018, covering 35 primary sampling units (PSUs) (30 randomly selected and five purposively selected 'suspected hotspots'). Ag-positivity was detected using Alere Filariasis Test Strips, and Ab-seropositivity (Bm14, Wb123, Bm33 Abs) were measured using multiplex bead assays. Seroprevalence was adjusted for study design and standardised for age and gender. NNTestav was calculated using the formula 1/p, where p was the adjusted seroprevalence for each subgroup.
Of 3795 participants (mean age: 20.7; 51.2% female), 1892 (49.9%) were LF-seropositive. If Ag alone was used to identify LF-seropositives, only 5% (117/1892) would be identified. Of the three Ab seromarkers, Bm14 Ab had the highest area under the Receiver-Operating Characteristic Curve ([ROC]=0.88) to classify participants as Ag-positive, followed by Wb123 Ab (ROC=0.83) and Bm33 Ab (ROC=0.76). Participants aged ≥10 years had lower NNTestav compared to participants aged 5-9 years for all seromarkers. NNTestav was lower in purposively versus randomly selected PSUs.
All Ab seromarkers had high ROC values to classify patients as Ag-positive and may be useful tools for LF surveillance in some settings. However, further research is required to fully understand how best Ab serosurveillance can be incorporated into LF elimination programmes.
需要灵敏的诊断工具来提示淋巴丝虫病（LF）的传播情况，以监测LF消除计划的进展。在某些情况下，抗丝虫抗体（Ab）标志物对于监测LF传播可能比抗原（Ag）即时检测更灵敏。本研究旨在通过以下方式调查抗丝虫抗体在萨摩亚检测LF传播信号的敏感性：i）调查抗体识别Ag阳性的敏感性和特异性；ii）估计识别LF血清阳性（Ag和/或任何抗体血清阳性）所需检测的平均人数（NNTestav）；iii）按目标年龄组和抽样设计比较不同血清学指标的效率。
2018年萨摩亚第一轮三轮药物大规模药物给药后1.5 - 3.5个月，对年龄≥5岁的参与者进行了基于社区的血清学调查，覆盖35个初级抽样单位（PSU）（30个随机选择和5个有目的地选择的“疑似热点地区”）。使用Alere丝虫病检测试纸检测Ag阳性，使用多重微珠分析法检测Ab血清阳性（Bm14、Wb123、Bm33抗体）。根据研究设计调整血清阳性率，并按年龄和性别进行标准化。使用公式1/p计算NNTestav，其中p是每个亚组的调整后血清阳性率。
在3795名参与者（平均年龄：20.7岁；51.2%为女性）中，1892人（49.9%）为LF血清阳性。如果仅使用Ag来识别LF血清阳性，只能识别出5%（117/1892）。在三种Ab血清标志物中，Bm14抗体在将参与者分类为Ag阳性方面的受试者工作特征曲线下面积最高（[ROC]=0.88），其次是Wb123抗体（ROC=0.83）和Bm33抗体（ROC=0.76）。对于所有血清标志物，年龄≥10岁的参与者的NNTestav低于5 - 9岁的参与者。在有目的选择的PSU中，NNTestav低于随机选择的PSU。
所有Ab血清标志物在将患者分类为Ag阳性方面都有较高的ROC值，在某些情况下可能是LF监测的有用工具。然而，需要进一步研究以充分了解如何最好地将Ab血清学监测纳入LF消除计划。
