Campers at a youth camp located in Brainerd, Minnesota became ill with cryptosporidiosis in July 2012. Camp dates were July 22-27. Sixteen cases were identified. Three campers submitted a stool sample to the Minnesota Department of Health (MDH) Public Health Laboratory (PHL). Cryptosporidium hominis subtype HGP4 was identified in all three specimens.

All campers reported swimming in the lake daily while at camp. Swallowing water while swimming was significantly associated with illness (6 of 13 cases vs. 4 of 26 controls; odds ratio 4.7; 95% confidence interval, 1.0 to 21.7; p=0.03). No specific cabin, drinking water exposure, or other camp activity was associated with illness.

The original source of contamination was not identified.