An Outbreak of Cryptosporidiosis From Fresh-Pressed Apple Cider

BACKGROUND: Recent waterborne outbreaks have established Cryptosporidium as an emerging enteric pathogen, but foodborne transmission has rarely been reported. In October 1993, an outbreak of cryptosporidiosis occurred among students and staff attending a 1-day school agricultural fair in central Maine. DESIGN: Environmental/laboratory investigation and cohort study. PARTICIPANTS: Attendees of the fair and their household members. MAIN OUTCOME MEASURES: Clinical or laboratory-confirmed cryptosporidiosis. Clinical cryptosporidiosis was defined as 3 days of either diarrhea (three loose stools in a 24-hour period) or vomiting. RESULTS: Surveys were completed for 611 (81%) of the estimated 759 fair attendees. Among attendees who completed the survey, there were 160 (26%) primary cases. Cryptosporidium oocysts were detected in the stools of 50 (89%) of 56 primary and secondary case patients tested. The median incubation period was 6 days (range, 10 hours to 13 days); the median duration of illness was 6 days (range, 1 to 16 days). Eighty-four percent of primary case patients had diarrhea and 82% had vomiting. Persons drinking apple cider that was hand pressed in the afternoon were at increased risk for cryptosporidiosis (154 54% of 284 exposed vs six 2% of 292 unexposed; relative risk, 26; 95% confidence interval, 12 to 59). Cryptosporidium oocysts were detected in the apple cider, on the cider press, and in the stool specimen of a calf on the farm that supplied the apples. The secondary household transmission rate was 15% (53/353). CONCLUSIONS: This is the first large cryptosporidiosis outbreak in which foodborne transmission has been documented. It underscores the need for agricultural producers to take measures to avoid contamination of foodstuffs with infectious agents common to the farm environment.