Ashiri Alireza, Rafiei Abdollah, Noordin Rahmah, Anuar Nor Suhada, Teimoori Ali, Ansari-Moghaddam Bijan, Beiromvand Molouk
Cellular and Molecular Research Center, Medical Basic Sciences Research Institute, Ahvaz Jundishapur University of Medical Sciences, Ahvaz, Iran.
Department of Parasitology, School of Medicine, Ahvaz Jundishapur University of Medical Sciences, Ahvaz, Iran.
Parasit Vectors. 2025 Jul 22;18(1):291. doi: 10.1186/s13071-025-06910-z.
Strongyloides stercoralis is a pathogenic nematode affecting the human intestine. Chronic strongyloidiasis often remains asymptomatic, posing diagnostic challenges due to the low sensitivity of conventional methods. Using traditional methods, this study investigated the prevalence of strongyloidiasis in Khuzestan Province, southwestern Iran. We also studied the effectiveness of a Strongyloides immunoglobulin G4 (IgG4) rapid diagnostic test (RDT) for timely infection detection before and after treatment.
This cross-sectional study, conducted during 2022-2024, evaluated 520 participants with eosinophilia (> 5%) for S. stercoralis infection. Coprological methods used were direct smear stool microscopy and agar plate culture. Serological methods were enzyme-linked immunosorbent assay (ELISA) (NovaTec kit) and a prototype IgG4 RDT using a recombinant antigen (NIE) . Traditional coprology and composite references were used to assess the diagnostic power. Among copro-positive patients, 30 cases were followed up at least 3 months after treatment using the same methods.
Of the 373 participants who submitted stool samples, coprological methods identified 95 positive cases, with culture proving to be more sensitive than direct smear (24.9%, 93/373 versus 7.5%, 28/373). Of the 520 participants, 35.2% (183/520) and 43.7% (227/520) tested positive for S. stercoralis using ELISA and IgG4 RDT, respectively. Spearman's rank correlation between the IgG4 RDT and ELISA was significant (ρ = 0.772; P < 0.001). Despite minor discrepancies, the IgG4 RDT showed substantial agreement with the ELISA (κ = 0.776). Increased eosinophil counts were strongly associated with Strongyloides infection with a mean of 20.48% in copro-positives versus 15.22 in copro-negatives and area under the curve (AUC) of 0.741 and 0.701 for coprology and the combination of coprology and serology methods (CRS), respectively. In the 30 follow-up patients, a significant reduction in eosinophil counts (P < 0.001) was observed. Five cases (17%) remained larva-positive, and serological tests significantly increased readings/scores. Three copro-negative patients showed strong positive results on ELISA and IgG4 RDT.
On the basis of the obtained results, the prevalence of S. stercoralis infection among the eosinophilic population was high. This study showed that the IgG4 RDT is a reliable and efficient diagnostic tool for S. stercoralis infection. The rapid test results demonstrated significant agreement with the ELISA and effectively detected infection in eosinophilic patients, making it a suitable diagnostic test for screening, particularly in resource-limited settings.
粪类圆线虫是一种影响人体肠道的致病性线虫。慢性粪类圆线虫病通常无症状，由于传统方法敏感性较低，给诊断带来挑战。本研究采用传统方法调查了伊朗西南部胡齐斯坦省粪类圆线虫病的流行情况。我们还研究了粪类圆线虫免疫球蛋白G4（IgG4）快速诊断试验（RDT）在治疗前后及时检测感染的有效性。
本横断面研究于2022年至2024年进行，评估了520名嗜酸性粒细胞增多（>5%）的参与者是否感染粪类圆线虫。采用的粪便学方法为直接涂片粪便显微镜检查和琼脂平板培养。血清学方法为酶联免疫吸附测定（ELISA）（诺华泰试剂盒）和使用重组抗原（NIE）的IgG4 RDT原型。采用传统粪便学和综合参考方法评估诊断能力。在粪便学检测阳性的患者中，30例在治疗后至少随访3个月，采用相同方法。
在提交粪便样本的373名参与者中，粪便学方法鉴定出95例阳性病例，培养法比直接涂片法更敏感（24.9%，93/373对7.5%，28/373）。在520名参与者中，分别有35.2%（183/520）和43.7%（227/520）使用ELISA和IgG4 RDT检测出粪类圆线虫阳性。IgG4 RDT与ELISA之间的Spearman等级相关性显著（ρ=0.772；P<0.001）。尽管存在细微差异，但IgG4 RDT与ELISA显示出高度一致性（κ=0.776）。嗜酸性粒细胞计数增加与粪类圆线虫感染密切相关，粪便学检测阳性者平均为20.48%，阴性者为15.22%，粪便学方法以及粪便学和血清学方法联合（CRS）的曲线下面积（AUC）分别为0.741和0.701。在30名随访患者中，观察到嗜酸性粒细胞计数显著降低（P<0.001）。5例（17%）仍为幼虫阳性，血清学检测显著提高了读数/分数。3例粪便学检测阴性的患者在ELISA和IgG4 RDT上显示强阳性结果。
根据获得的结果，嗜酸性粒细胞增多人群中粪类圆线虫感染的患病率较高。本研究表明，IgG4 RDT是诊断粪类圆线虫感染的可靠且有效的诊断工具。快速检测结果与ELISA显示出显著一致性，并有效检测出嗜酸性粒细胞增多患者的感染，使其成为一种适合筛查的诊断试验，特别是在资源有限的环境中。
