Seroepidemiological studies of Chlamydia pneumoniae infections in 1-36 months old children with respiratory tract infections and other diseases in Poland.

Presence of specific IgM, IgG and IgA antibodies against Chlamydia pneumoniae was evaluated in children aged 1 week to 36 months to investigate the role of C. pneumoniae in respiratory infections and other diseases. Serum samples were obtained from 150 hospitalized children, including 123 children presenting the clinical symptoms of various respiratory tract infections, two children with acute diarrhoea, two children with meningitis, 14 children with urinary tract infection, and 9 children with non-infectious diseases. Levels of specific C. pneumoniae IgM, IgG and IgA serum antibodies were measured by enzyme-linked immunoassay (ELISA). C. pneumoniae IgM antibodies were detected in 16 (13.0 %) of 123 children with respiratory tract infections. Specific IgG antibodies were found in sera of 11 children under 12 months old. Among 27 children without symptoms of a respiratory tract disease, specific C. pneumoniae IgM were found in two (7.4%) children, including one child with meningitis and another child with urinary tract infection. Specific IgA antibodies were not found in any tested child. All cases of C. pneumoniae infections were identified within two calendar years out of eight that were analyzed, i.e. in 1997 and 2000. The incidence of C. pneumoniae infections varied seasonally, with most children infected in autumn. C. pneumoniae IgM antibodies were detected more often in girls (17.9%) then in boys (7.2%). C. pneumoniae infections occur among small children in central Poland. The results of this study indicate that C. pneumoniae may play a role in the etiology of respiratory tract infections in infants and young children.