Laboratory of Biodiversity and Ecosystem Management, Jean Lorougnon Guédé University, Daloa, Côte d'Ivoire.
National Program for Neglected Tropical Disease Control, Patient Management, Ministry of Health, Conakry, Guinea.
Infect Dis Poverty. 2024 Jul 8;13(1):53. doi: 10.1186/s40249-024-01220-5.
Serological screening tests play a crucial role to diagnose gambiense human African trypanosomiasis (gHAT). Presently, they preselect individuals for microscopic confirmation, but in future "screen and treat" strategies they will identify individuals for treatment. Variability in reported specificities, the development of new rapid diagnostic tests (RDT) and the hypothesis that malaria infection may decrease RDT specificity led us to evaluate the specificity of 5 gHAT screening tests.
During active screening, venous blood samples from 1095 individuals from Côte d'Ivoire and Guinea were tested consecutively with commercial (CATT, HAT Sero-K-SeT, Abbott Bioline HAT 2.0) and prototype (DCN HAT RDT, HAT Sero-K-SeT 2.0) gHAT screening tests and with a malaria RDT. Individuals with ≥ 1 positive gHAT screening test underwent microscopy and further immunological (trypanolysis with T.b. gambiense LiTat 1.3, 1.5 and 1.6; indirect ELISA/T.b. gambiense; T.b. gambiense inhibition ELISA with T.b. gambiense LiTat 1.3 and 1.5 VSG) and molecular reference laboratory tests (PCR TBRN3, 18S and TgsGP; SHERLOCK 18S Tids, 7SL Zoon, and TgsGP; Trypanozoon S-RT-qPCR 18S2, 177T, GPI-PLC and TgsGP in multiplex; RT-qPCR DT8, DT9 and TgsGP in multiplex). Microscopic trypanosome detection confirmed gHAT, while other individuals were considered gHAT free. Differences in fractions between groups were assessed by Chi square and differences in specificity between 2 tests on the same individuals by McNemar.
One gHAT case was diagnosed. Overall test specificities (n = 1094) were: CATT 98.9% (95% CI: 98.1-99.4%); HAT Sero-K-SeT 86.7% (95% CI: 84.5-88.5%); Bioline HAT 2.0 82.1% (95% CI: 79.7-84.2%); DCN HAT RDT 78.2% (95% CI: 75.7-80.6%); and HAT Sero-K-SeT 2.0 78.4% (95% CI: 75.9-80.8%). In malaria positives, gHAT screening tests appeared less specific, but the difference was significant only in Guinea for Abbott Bioline HAT 2.0 (P = 0.03) and HAT Sero-K-Set 2.0 (P = 0.0006). The specificities of immunological and molecular laboratory tests in gHAT seropositives were 98.7-100% (n = 399) and 93.0-100% (n = 302), respectively. Among 44 reference laboratory test positives, only the confirmed gHAT patient and one screening test seropositive combined immunological and molecular reference laboratory test positivity.
Although a minor effect of malaria cannot be excluded, gHAT RDT specificities are far below the 95% minimal specificity stipulated by the WHO target product profile for a simple diagnostic tool to identify individuals eligible for treatment. Unless specificity is improved, an RDT-based "screen and treat" strategy would result in massive overtreatment. In view of their inconsistent results, additional comparative evaluations of the diagnostic performance of reference laboratory tests are indicated for better identifying, among screening test positives, those at increased suspicion for gHAT.
The trial was retrospectively registered under NCT05466630 in clinicaltrials.gov on July 15 2022.
血清学筛查试验在诊断冈比亚锥虫病（gHAT）方面起着至关重要的作用。目前，它们用于对疑似个体进行显微镜确认，但在未来的“筛查和治疗”策略中，它们将用于确定需要治疗的个体。由于报告的特异性存在差异、新的快速诊断检测（RDT）的发展以及疟疾感染可能降低 RDT 特异性的假设，我们评估了 5 种 gHAT 筛查检测的特异性。
在主动筛查期间，连续检测了来自科特迪瓦和几内亚的 1095 个人的静脉血样本，使用商业（CATT、HAT Sero-K-SeT、Abbott Bioline HAT 2.0）和原型（DCN HAT RDT、HAT Sero-K-SeT 2.0）gHAT 筛查检测和疟疾 RDT。对于≥1 种 gHAT 筛查检测阳性的个体，进行显微镜检查和进一步的免疫（用 T.b. gambiense LiTat 1.3、1.5 和 1.6 进行锥虫溶解试验；间接 ELISA/T.b. gambiense；用 T.b. gambiense LiTat 1.3 和 1.5 VSG 进行 T.b. gambiense 抑制 ELISA）和分子参考实验室检测（PCR TBRN3、18S 和 TgsGP；SHERLOCK 18S Tids、7SL Zoon 和 TgsGP；Trypanozoon S-RT-qPCR 18S2、177T、GPI-PLC 和 TgsGP 多重检测；RT-qPCR DT8、DT9 和 TgsGP 多重检测）。显微镜检测到的寄生虫确认了 gHAT，而其他个体被认为没有 gHAT。通过卡方检验评估组间差异，通过 McNemar 检验评估同一个体上两种检测方法的特异性差异。
诊断出 1 例 gHAT 病例。总体检测特异性（n=1094）为：CATT 98.9%（95%CI：98.1-99.4%）；HAT Sero-K-SeT 86.7%（95%CI：84.5-88.5%）；Bioline HAT 2.0 82.1%（95%CI：79.7-84.2%）；DCN HAT RDT 78.2%（95%CI：75.7-80.6%）；HAT Sero-K-SeT 2.0 78.4%（95%CI：75.9-80.8%）。在疟疾阳性者中，gHAT 筛查检测的特异性较低，但在几内亚，Abbott Bioline HAT 2.0（P=0.03）和 HAT Sero-K-Set 2.0（P=0.0006）的差异具有统计学意义。gHAT 血清阳性者的免疫和分子实验室检测特异性分别为 98.7-100%（n=399）和 93.0-100%（n=302）。在 44 例参考实验室检测阳性者中，仅确认的 gHAT 患者和 1 例筛查试验血清阳性者同时具有免疫和分子参考实验室检测阳性。
尽管不能排除疟疾的轻微影响，但 gHAT RDT 的特异性远低于世界卫生组织目标产品特性规定的 95%最小特异性，这是一种用于确定适合治疗个体的简单诊断工具。除非特异性得到提高，否则基于 RDT 的“筛查和治疗”策略将导致大量过度治疗。鉴于它们不一致的结果，需要对参考实验室检测的诊断性能进行额外的比较评估，以便更好地在筛查试验阳性者中识别出那些对 gHAT 高度怀疑的患者。
该试验于 2022 年 7 月 15 日在 clinicaltrials.gov 上以 NCT05466630 号进行了回顾性注册。
