Outbreak of cryptosporidiosis in a day-care center.

An outbreak of diarrhea due to infection with Cryptosporidium occurred in a day-care center. During a period of 2 months, 23 of 53 (43%) children attending the day-care center and 15 of 104 (14%) household contacts had diarrhea. Cryptosporidium oocysts were identified in 13 of 20 (65%) symptomatic children tested compared with three of 27 (11%) asymptomatic children (chi 2 = 12.56, P less than .001). Enteropathogenic bacteria, enteroviruses, rotavirus, and other protozoan parasites were ruled out as the cause of the diarrhea. A history of diarrhea in household contacts was associated with excretion of Cryptosporidium oocysts by the children. Human-to-human transmission of the infection was suggested by the epidemiology.