Rapid diagnostic tests relying on antigen detection from stool as an efficient point of care testing strategy for giardiasis and cryptosporidiosis? Evaluation of a new immunochromatographic duplex assay

Abstract Microscopy is the gold standard for the diagnosis of gastrointestinal parasites but is time-consuming and dependent on operator skills. Rapid diagnostic testsrepresent alternative methods but most evaluations have been conducted on a limited number of samples preventing their implementation in the clinical setting. We evaluated a new CE-IVD marked immunochromatographic assay (Crypto/ GiardiaK-SeT®, CorisBioconcept) for the detection of G. intestinalis and Cryptosporidiumspp. in 2 phases (retrospective and prospective) on a set of 482 stool samplesincluding rare Cryptosporidiumspecies. Besides G. intestinalis , this test could represent a rapid and reliable alternative to the modified Ziehl-Neelsen stainingfor the diagnosis of cryptosporidiosis (sensitivity/specificity were 89.2%/99.3% and 86.7%/100% for G. intestinalis and Cryptosporidiumresp.), reducing diagnostic delays. Such strategy would also be time-saving by avoiding wet mount microscopy and concentrations steps, being particularly appropriate for laboratories having little expertise in microscopy or not able to implement molecular diagnostic methods.