Mimicking Filtration of Cryptosporidium Parvum in Porus Media Using Biotin and Glycoprotien-Coated Microspheres

Cryptosporidium parvum is a highly infectious protozoan. Insufficient removal of C. parvum in drinking water has resulted in many cryptosporidiosis outbreaks worldwide. Due to its longevity and extreme resistance to chlorination, removal of C. parvum in porous media is predominantly by filtration. However, currently no reliable surrogates have been established for C. parvum removal by filtration.

Latex microspheres of similar size, density and shape as C. parvum oocysts were coated with biotin and glycoprotein, which had similar surface charges to that of C. parvum. Glycoprotein also mimicked the type of surface protein of the oocysts. 

Filtration experiments with two different sand media demonstrated that, compared to the unmodified microspheres, the surrogates achieved a superior match to the retention of the C. parvum oocysts, showing the same log-reduction. In contrast, results from the unmodified microspheres differed one-order of magnitude. Detection of the fluorescently surrogates was rapid using a spectrofluorometer, contrasting to time-consuming microscopic examination of C. parvum. The surrogates remained stable in size and charge for at least 22 months. 

When validation in pilot trials, the surrogates developed here could have potential uses in assessing C. parvum filtration in sand filters in water treatment and water recycling through land disposal.