Evidence base of incubation periods, periods of infectiousness and exclusion policies for the control of communicable diseases in schools and preschools

Background. The optimal control of communicable diseases requires accurate information on incubation periods, periods of infectiousness and the effect iveness of exclusion. We collected the available evidence for a wide range of infections and infestations and produced evidence-based guidelines for t heir control in schools and preschools. Methods. A thorough MEDLINE literature search was conducted on the incubati on period, period of infectiousness and effectiveness of exclusion for 41 i nfections. The quality of the information obtained was indicated by levels of evidence. The information was used to produce guidelines on exclusion, a nd the recommendations were graded according to the levels of evidence avai lable. Grades A, B and C represented strongly, reasonably and poorly eviden ce-based recommendations, respectively. Results. The quality of data obtained was highly variable. Information on i ncubation periods was obtained for all 41 infections and was generally of g ood quality. Information on periods of infectiousness and effectiveness of exclusion was of a lesser quality and was found for only 11 and 4 condition s, respectively. There were 3 Grade A, 17 Grade B and 21 Grade C recommenda tions on exclusion. Examples of exclusion periods include: 5 days for chick enpox, measles, mumps, rubella, pertussis and scarlet fever; and 24 h from the cessation of diarrhea for most gastrointestinal diseases. In contrast t o existing guidelines exclusion was not recommended for school age children with hepatitis A. Conclusions. We have been able to present the best available data on the in cubation periods and periods of infectiousness of 41 childhood infections. It was possible to produce strongly or reasonably evidence-based guidelines on exclusion periods for approximately one-half of the infections.