During 2000, 197 cases of laboratory-confirmed Cryptosporidium parvum infection were reported (4.0 per 100,000 population). This represents a 116% increase from the 91 cases reported in 1999 and a 34% increase from the mean annual number of cases reported from 1996 to 1999 (mean, 147 cases; range, 81 to 242 cases).
Demographic characteristics of cases in 2000 were similar to previous years. Sixty (30%) cases were from southeastern Minnesota, and 43 (22%) were from the seven-county metropolitan area. Cases ranged in age from 3 months to 81 years, with a median of 9 years. Children less than 10 years of age accounted for 52% of cases, while children less than 5 years of age accounted for 30%. Seventy-eight percent of cases had onset during July through October. Twelve percent of cases were hospitalized.
Seven outbreaks of cryptosporidiosis were identified in 2000, accounting for 48 (24%) confirmed cases. Four outbreaks were associated with swimming pools, two were associated with beaches, and one was associated with contact with ill calves at a day camp. Excluding outbreak-associated cases, there still was a substantial increase in cases reported in 2000 (149 cases) compared to 1999 (81 cases).