Cryptosporidium Diagnostic Assays: Microscopy

Stained microscopy of fecal smears was the cornerstone of Cryptosporidium diagnosis for many years and provides a low-cost method for detecting oocysts. The development and commercialization of improved enzyme immunosorbent assays (EIAs) for coproantigen detection provided an automatable method for mass testing and rapid diagnostics when incorporated onto a cartridge format. Similarly, immunochromatographic lateral flow (ICLF) assays enable rapid diagnostics. Nevertheless, it is important that positive reactions by EIAs or ICLF assays are confirmed. Here, we describe microscopical methods using tinctorial stains for the diagnosis of acute cryptosporidiosis and using immunofluorescent reagents for diagnosis or for confirmation of EIA- or ICLF-positive reactions.