背景:蛔虫和其他土壤传播的蠕虫(STH)感染的标准诊断依赖于通过共显微镜检测蠕虫卵。然而,此方法依赖于蠕虫的通畅性,在低强度感染设置中仅显示有限的准确性。我们的目的是破译不同抗体的诊断准确性使用各种Ascaris抗原参考共显微镜和定量PCR(qPCR),在肯尼亚西部的学龄儿童中进行国家STH预防性化疗四个月后。
方法:通过共显微镜(Kato-Katz和mini-FLOTAC)和qPCR评估了390名学童的STH感染状况。并行,针对幼虫和成虫裂解物的蛔虫特异性抗体谱,通过酶联免疫吸附测定和成虫排泄分泌(ES)产物。使用密切相关的人畜共患round虫物种Toxcaracati和Toxcaracanis评估了抗体的交叉反应性。使用受试者工作曲线分析和相应的曲线下面积(AUC)评估每种抗体的诊断准确性。
结果:蛔虫是主要的蠕虫感染,总患病率为14.9%(58/390)。mini-FLOTAC和Kato-Katz对蛔虫诊断的敏感性仅为53.5%和63.8%,分别与qPCR进行比较。虽然更敏感,qPCR值与显微卵数相关(R=-0.71,P<0.001),与抗体水平相反。引人注目的是,通过qPCR和显微镜确定,识别成年A虫的ES产物的IgG抗体可靠地诊断为活动性A虫感染,IgG1显示最高的准确性(AUC=0.83,95%CI:0.75-0.91)。
结论:针对成年蛔虫-ES产品的IgG1抗体反应在补充用于监测蛔虫感染的标准粪便和分子技术方面具有很有希望的潜力。这在驱虫程序的背景下特别重要,因为抗体诊断准确性与卵计数无关。
BACKGROUND: The standard diagnosis of Ascaris lumbricoides and other soil-transmitted helminth (STH) infections relies on the detection of worm eggs by copromicroscopy. However, this method is dependent on worm patency and shows only limited accuracy in low-intensity infection settings. We aimed to decipher the diagnostic accuracy of different antibodies using various Ascaris antigens in reference to copromicroscopy and quantitative PCR (qPCR), four months after national STH preventative chemotherapy among school children in western Kenya.
METHODS: STH infection status of 390 school children was evaluated via copromicroscopy (Kato-Katz and mini-FLOTAC) and qPCR. In parallel, Ascaris-specific antibody profiles against larval and adult worm lysates, and adult worm excretory-secretory (ES) products were determined by enzyme-linked immunosorbent assay. Antibody cross-reactivity was evaluated using the closely related zoonotic roundworm species Toxocara cati and Toxocara canis. The diagnostic accuracy of each antibody was evaluated using receiver operating curve analysis and the correspondent area under the curve (AUC).
RESULTS: Ascaris was the predominant helminth infection with an overall prevalence of 14.9% (58/390). The sensitivity of mini-FLOTAC and Kato-Katz for Ascaris diagnosis reached only 53.5% and 63.8%, respectively compared to qPCR. Although being more sensitive, qPCR values correlated with microscopic egg counts (R = -0.71, P<0.001), in contrast to antibody levels. Strikingly, IgG antibodies recognizing the ES products of adult Ascaris worms reliably diagnosed active Ascaris infection as determined by qPCR and microscopy, with IgG1 displaying the highest accuracy (AUC = 0.83, 95% CI: 0.75-0.91).
CONCLUSIONS: IgG1 antibody responses against adult Ascaris-ES products hold a promising potential for complementing the standard fecal and molecular techniques employed for monitoring Ascaris infections. This is of particular importance in the context of deworming programs as the antibody diagnostic accuracy was independent of egg counts.