Daycare attendance and risk of first infectious disease.

The health hazards of daycare attendance for the development of upper and lower respiratory tract infections have been well documented; however the importance and the mechanism of this association have not been well defined. In order to ascertain the risk associated with the beginning of daycare (DC) attendance we conducted a survey on 1263 children aged from 3 months to 3 years; the analysis focused on the risk of developing an initial episode of common cold with fever, a first otitis and a first wheezy bronchitis (WB) within the 2 month period following admission to DC. For each 2 month period, the risk of a first infectious event was much higher in children who had just begun attending DC than in children who remained at home; the risk ratio varied from 1.7 to 2.4 for common cold, from 1.5 to 1.9 for otitis and from 1.8 to 3.2 for WB. Because age at onset of the first infectious event may be related to a higher risk of repeated events we consider that admission to DC under 12 months of age should be questioned.