An outbreak of gastroenteritis occurred in a school affecting more tha
n 30% of its 535 students. An epidemiological survey questionnaire was
given to all students as well as staff and maintenance personnel. Sto
ol cultures and electronic microscopy were used to detect the presence
of a Norwalk-like virus. Several analysis of water samples were also
done. This outbreak occurred simultaneously in the two wings of the sc
hool (East and South). Those who used the East wing were most affected
by the disease (RR = 1.45, CI 95%: 1,14-1,85). There was no indicatio
n of food or water supply contamination. A Norwalk-like virus was iden
tified in the stool sample of one child. This along with the clinical
characteristics strongly suggested that the pathogen was indeed a Norw
alk-like virus. The analysis suggests transmission via contaminated su
rfaces but also via airborne transport of the infectious agent.