Asymptomatic carriage of protozoan parasites in children in day care centers in the United kingdom.

Point prevalence of Cryptosporidium and Giardia carriage among 230 asymptomatic preschool children attending day-care facilities was 1.3% (95% CI: 0.3%–3.8%) for each parasite, with no dual infections. Cryptosporidium oocysts were detected by immunomagnetic separation and immunofluorescence microscopy and genotyped: one isolate was Cryptosporidium hominis, the other 2 being skunk and cervine genotypes, rarely found in symptomatic human infection.