Chlamydia pneumoniae in children attending day-care centers in Gavle, Sweden

Background. The epidemiology of Chlamydia pneumoniae in healthy children has not been established. Methods. This investigation used polymerase chain reaction (PCR) to study the epidemiology of C, pneumoniae in presumed healthy children. Four hundred fifty-three children and 142 personnel at 9 day-care centers were investigated for carriage of C, pneumoniae, Children found to be positive by PCR were also investigated with serology, and their family members were tested with PCR, Results. One hundred and three (22.7%) children had a positive PCR, as had 33 (23.2%) personnel. Fourteen percent of the children younger than 3 years had a positive PCR test compared with 26% of the older children (P < 0.01). No correlation was found between respiratory symptoms and carriage of C, pneumoniae, Mothers were more often positive in the PCR test as compared with fathers (relative risk, 2.59; 95% confidence interval, 1.16 to 5.78), Antibodies to C, pneumoniae were found in 27 of 97 PCR-positive children; only 2 of whom were younger than 3 years. Conclusion C. pneumoniae can be commonly found in young children attending day care. Most of the youngest children did not develop specific antibodies, Children may have subclinical infections with C, pneumoniae, The organism seems to be easily communicable among individuals living in close proximity.