Abstract
Two ELISA methods were investigated for the quantitative detection of viability and infectivity of Cryptosporidium parvum oocysts. One is to detect the sporozoites attached to the cell surface, and another is to detect the oocysts developing in host cell. It was thought that the former method, named “Fixed-cell” ELISA, could assess the viability of oocysts, and the latter method, named “Living-cell” ELISA, could assess the infectivity of oocysts. In both ELISA systems, the resulting optical density was related to the number of oocysts inoculated. Inactivation of oocyst by ultraviolet (UV) irradiation was evaluated using these two ELISA systems. One-log reduction in infectivity of oocysts was achieved by 10 mW·s·cm-2 of UV irradiation. At this UV dose, no reduction in viability determined by “Fixed-cell” ELISA was observed.
