An outbreak of foodborne giardiasis.

G LAMBLIA is recognized as an important cause of acute illness in human beings. Community-wide waterborne outbreaks of giardiasis . have been documented with increasing frequency,' ' and backpackers have become ill after drinking water from mountain streams. 6 ' 7 Giardiasis has also occurred among travelers to foreign countries, although the methods of transmission in these situations are not clear." Person-to-person transmission has been demonstrated in mental institutions," " in day-care centers," 15 and among male homosexuals.' 6' 8 To our knowledge, fecally contaminated food has not been documented to be a vehicle for the transmission of giardiasis, even though the fecal-oral route of transmission has been well established." We report here an outbreak of foodborne giardiasis. On December 13, 1979, a physician notified the Minnesota Department of Health (MDH) that two employees of the Goodhue, Minnesota Public School System were being treated for giardiasis. The physician also reported that the ill employees had estimated that more than half the other employees of the school had a similar diarrheal illness. After a discussion with local school and public-health officials, the MDH initiated an investigation. Goodhue is a farming community in southeastern Minnesota with a population of 630. The major employer in the community is the consolidated rural school system, which serves 649 students in kindergarten through grade 12 and retains 60 employees. The community is served by a chlorinated but unfiltered public water system. The source of the water is a municipal well; there was no evidence of contamination during the two years before the outbreak. The school consists of one building built in 1935 and three additions that were built in 1953, 1960, and 1970. The employees have access to either of the two employee lounges, designated for smokers and nonsmokers. One is located in the original building, and the other is in the section added in 1960. A central kitchen facility, located in the building, provides approximately 500 daily lunches for employees and students in all grades. The school is connected to the public water system.