The Novodiag (R) Stool parasites assay, an innovative high-plex technique for fast detection of protozoa, helminths and microsporidia in stool samples: a retrospective and prospective study

Objectives: We provide the first evaluation of the CE-IVD marked Novodiag (R) stool parasites assay (NVD), allowing rapid and high-plea detection of 26 distinct targets, encompassing protozoans, helminths and microsporidia in stool samples. Methods: A total of 254 samples (n = 205 patients) were prospectively processed by the NVD and our routine procedure (RP). Performances of the NVD were compared with RP. Samples only positive by the NVD assay were investigated by external PCR assays. Sensitivity and specificity (Se/Sp) and time from sample receipt to results were determined for each method. The NVD was also evaluated against 77 additional samples positive for a wide range of parasites. Results: Overall positivity rate was 16.9% for RP compared with 34% using the NVD assay, and 164 samples (66%) were negative by both methods. Only 30 positive samples (12%) showed full concordance between RP and NVD. Fifty-three discordant samples were sent for external investigations. Except for Giardia intestinalis and Trichuris spp., higher Se was observed for the NVD assay for Blastocystis spp. (100% vs. 63%), Dientamoeba fragilis (100% vs. 0%), Schistosoma spp. (100% vs. 17%), and Enterobius vermicularis (100% vs. 67%) but roughly similar to RP for the remaining parasites tested. False-positive results were identified for Blastocystis spp., G. intestinalis, and Trichuris spp. using the NVD assay. The NVD mostly provides a diagnosis on the day of sample receipt compared with a mean of three days with RP. Conclusions: Besides some limitations, the NVD is a new diagnostic strategy allowing rapid and high-plea detection of gastrointestinal parasites from unpreserved stools.