Target product profiles for new diagnostics to inform strongyloidiasis control programs
Authors: Kazienga Adama , Coffeng Luc E. , Roose Sara , de Vlas Sake , Buonfrate Dora , Scarso Salvatore , Tamarozzi Francesca , Levecke Bruno 
Published: December 2024

Background

The World Health Organization calls for the development of new diagnostics to support large-scale deworming programs against strongyloidiasis. To better steer research and development (R&D) of new diagnostics, it is imperative to identify the minimal requirements that new diagnostics should meet, the so-called target product profiles (TPPs). While diagnostic TPPs exist for other major soil-transmitted helminthiases, none exist for strongyloidiasis.

Methods

We investigated a range of potential diagnostic TPPs using our previously developed simulation framework for the effect of imperfect diagnostics on the cost and correctness of program decisions. With this framework, we studied the minimum requirements for diagnostic performance, cost per test and sample throughput for future assays while comparing the survey costs with those of the reference Baermann method. As potential assay platforms, we considered antibody (Ab)-detecting assays, including a point-of-care lateral flow assay (LFA) and a laboratory-based Ab-ELISA. We also determined cost-efficient school-based survey designs for two currently available assays: Bordier Ab-ELISA and a prototype NIE-LFA.

Principal findings

Our findings highlighted that (i) specificity rather than sensitivity is a critical parameter to consider for R&D of new diagnostic methods for monitoring control programs; (ii) the requirements for diagnostic performance became less stringent with an increasing sample size and when higher risks of incorrect decision-making were accepted. When focusing on the assay formats, the LFA resulted in lower survey costs compared to the Baermann method. Ab-ELISA was cost-efficient only if the diagnostic performance was nearly perfect combined with low cost per test and high sample throughput. Of all the three assays considered here, the prototype NIE-LFA allowed for the most cost-efficient survey designs.

Conclusion/significance

R&D should focus on developing point-of-care assays with high specificity. The prototype NIE-LFA is a cost-efficient alternative to Baermann to support control programs for strongyloidiasis.

Author summary

The World Health Organization calls for the development of rapid, easy-to-use, and performant point-of-care diagnostics to follow up large-scale deworming programs against strongyloidiasis. However, there are no further recommendations regarding the required performance and cost of such new diagnostics. We performed a simulation study and a cost analysis to assess the minimum requirements in terms of diagnostic sensitivity and specificity, cost per test, and sample throughput for future assays while comparing the survey costs with those of a reference method. In addition, we determined the most cost-efficient survey designs to support control programs for strongyloidiasis applying currently available assays. Our results indicate that research & development efforts should focus on developing point-of-care assays with high specificity. Of the currently available diagnostics, a prototype of a rapid diagnostic test resulted in the lowest total survey cost, while restricting the risk of incorrect policy decisions to the minimum.