In May 1995, the Scientific Institute of Public Health was informed of an o
utbreak of gastrointestinal illness in a congregational school in the Bruss
els area. The field investigation identified 24 cases with mild to severe g
astrointestinal and general symptoms of acute bacterial enterocolitis. Camp
ylobacter coli was detected in the stools of 5 patients. A retrospective co
hort study suggested that a mixed salad (containing ham and feta cheese) wa
s the probable source of infection, but the route of contamination remained
unknown. The rapid investigation of such episodes of collective foodborne
infections is essential for the implementation of adequate control measures
.