Accuracy, acceptability, and feasibility of diagnostic tests for the screening of Strongyloides stercoralis in the field (ESTRELLA): a cross-sectional study in Ecuador

Tamarozzi, Francesca; Guevara, Ángel; Anselmi, Mariella; Vicuña, Yosselin; Prandi, Rosanna; Marquez, Monica; Vivero, Sandra; Huerlo, Francisco Robinzón; Racines, Marcia; Mazzi, Cristina; Denwood, Matthew; Buonfrate, Dora

doi:10.1016/s2214-109x(23)00108-0

Cited by 15 publications

(8 citation statements)

References 33 publications

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“…This assumption was based on the prevalence of symptoms among cases with diagnosed infection 26 and the fact that the sensitivity of Baermann or stool culture is in the order of 50%. 11,27,28 Therefore, we are ignoring potential YLDs in undiagnosed cases of infection, meaning that our estimates of cost-effectiveness are conservative. However, as this equally affects our estimates for school-based and community-based PC, we do not expect that this uncertainty about the proportion of infected cases with symptoms affects our conclusions about community-based PC being the most cost-effective strategy.…”

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

“…This assumption was based on the observation that of people with detected infection based on Baermann or stool culture, 53% experience abdominal pain, 41% report diarrhoea, and 28% have urticaria or rash, 26 combined with the fact that the sensitivity of Baermann or stool culture is in the order of 50%. 11,27,28 With this approach, we ignore potential cases of undiagnosed infection who may yet have symptoms.…”

Section: Years Lived With Disabilitymentioning

confidence: 99%

“…10 Even with diagnostic techniques that are optimised for strongyloidiasis, the sensitivity of a single stool-based diagnostic test (Baermann, Kogar Agar plate culture, or PCR) is in the order of 50% to 60%, while that of a single serological test is in the order of 65% (Bordier ELISA) to 80% (Strong Detect ELISA). 11 As such, surveys to delineate STH-endemic areas typically underestimate the true prevalence of strongyloidiasis, especially when using stool microscopy. Combined with the lack of an established cut-off in terms of minimal prevalence of infection for initiating a control program, this poses a major challenge to decide where to implement strongylodiasis control measures.…”

Section: Introductionmentioning

confidence: 99%

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Cost-effectiveness of mass drug administration with ivermectin against strongyloidiasis: a modelling study

Coffeng,

Lo,

de Vlas

2024

Preprint

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Background: Strongyloidiasis, caused by the parasitic intestinal worm Strongyloides stercoralis, infects hundreds of millions of people globally. Current school-based preventive chemotherapy (PC) programs that use benzimidazole derivatives (e.g., albendazole) against soil-transmitted helminths do not effectively treat strongyloidiasis, which requires treatment with ivermectin. We estimate the cost-effectiveness of mass drug administration with ivermectin for the control of strongyloidiasis. Methods: We developed a mathematical model to simulate the population dynamics of S. stercoralis and the impact of school-based and community-wide PC across a range of epidemiological settings. We simulated 10-year PC programs with varying treatment coverages. We estimated a primary outcome of disability-adjusted life years (DALYs) averted by each PC strategy and calculate the programmatic cost (US$) of each strategy. We estimated cost-effectiveness by comparing strategies by their incremental cost-effectiveness ratios (US$/averted DALY) and expected loss curves. Findings: The model found community-based PC was the most cost-effective strategy (≤600 US$ / DALY averted), despite costing approximately 5 times as much as school-based PC. Community-based PC targeted at ages 5 and above reduced infection levels close to 0% within 5 to 6 years. School-based PC was predicted to have very little impact. These results were robust across a range of epidemiologic settings above a measured prevalence of 2-5% in school age children. Interpretation: Annual community-based PC is the most cost-effective public health strategy to control strongyloidiasis, being superior to school-based PC due to most of the infections and mortality occurring in adults. A baseline prevalence of 2% of infection in school age children, as measured by Baermann or stool culture, is a suitable minimum threshold for cost-effective implementation of community-based PC. Funding: World Health Organization.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Years Lived With Disabilitymentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Cost-effectiveness of mass drug administration with ivermectin against strongyloidiasis: a modelling study

Coffeng,

Lo,

de Vlas

2024

Preprint

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“…In both studies, the assay demonstrated good accuracy, with excellent specificity (around 98% in both studies) and good sensitivity (ranging from 78% to 98.6%). More recently, the assay has also been evaluated in a prospective diagnostic study carried out in Ecuador (Tamarozzi et al ., 2023 ). In the latter study, the test was performed using dried blood spots collected on filter paper, and sensitivity and specificity were 83.5% (credible intervals [CI] 73.8–91.8) and 91.7% (CI 89.6–93.8), respectively.…”

Section: Introductionmentioning

confidence: 99%

Evaluation of the SsIR/NIE recombinant antigen ELISA for the follow up of patients infected by Strongyloides stercoralis: a diagnostic study

Prato,

Tamarozzi,

Tais

et al. 2024

Parasitology

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Some serology assays demonstrated useful for post-treatment monitoring of Strongyloides stercoralis infection. Serology frequently has low specificity, which might be improved by the use of recombinant antigens. The Strongy Detect ELISA is based on 2 recombinant antigens (SsIR and NIE) and proved good accuracy. Aim of this study was to evaluate the performance of this test for the post-treatment monitoring of strongyloidiasis. We tested 38 paired sera, with matched fecal tests results, stored in our biobank and originating from a randomized controlled trial. At baseline, all patients tested positive for at least 1 fecal assay among PCR, direct stool microscopy and agar plate culture. Patients were re-tested with both serology and fecal assays 12 months after treatment. Primary outcome was the relative reduction in optical density (OD) between baseline and follow up. We observed that about 95% samples showed a reduction between pre and post-treatment OD, with a median relative reduction of 93.9% (IQR 77.3%–98.1%). In conclusion, the test proved reliable for post-treatment monitoring. However, some technical issues, including that the threshold for positivity has not be predefined, and that a substantial number of samples showed overflow signals, need to be fixed to permit use in routine practice.

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An evaluation of a lateral flow rapid diagnostic test for Strongyloides stercoralis infection

Nickel,

Krebs,

Ruf

et al. 2024

Acta Tropica

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Accuracy, acceptability, and feasibility of diagnostic tests for the screening of Strongyloides stercoralis in the field (ESTRELLA): a cross-sectional study in Ecuador

Cited by 15 publications

References 33 publications

Cost-effectiveness of mass drug administration with ivermectin against strongyloidiasis: a modelling study

Cost-effectiveness of mass drug administration with ivermectin against strongyloidiasis: a modelling study

Evaluation of the SsIR/NIE recombinant antigen ELISA for the follow up of patients infected by Strongyloides stercoralis: a diagnostic study

An evaluation of a lateral flow rapid diagnostic test for Strongyloides stercoralis infection

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