Effect of ultraviolet disinfection of drinking water on the viability of Cryptosporidium parvum oocysts.

Demineralized water was enriched with a known number of Cryptosporidium parvum oocysts obtained from fresh calf feces, which were purified and exposed to ultraviolet (UV) light (15,000 mW/sec) for different lengths of time. Coccidium-free litters of CD-1 neonatal mice then were inoculated intragastrically with the treated water. Seven days postinoculation mice were killed and C. parvum infection prevalence and intensity determined. In mice inoculated with C. parvum-enriched water that had been exposed to UV light for at least 150 min, no infection occurred.