Prevalence of antibodies to Chlamydia pneumoniae in an Israeli population without clinical evidence of respiratory infection

Aims: To estimate the occurrence of recent, past, and “persistent” infections with Chlamydia pneumoniae—as indicated by serology—in an Israeli population without clinical evidence of respiratory infection. Methods: Serum samples from 402 subjects (172 children and 230 adults), without known respiratory symptoms, were collected. Antibodies to C pneumoniae (IgG, IgA, and IgM) were evaluated using the microimmunofluorescence (MIF) assay. Antibody prevalence and indication of recent, past, and persistent infections were calculated and their distribution determined according to age, sex, and season. Results: Antibodies to C pneumoniae were detected in 53 children (31%) and 171 adults (74%). Recent infection was indicated in only one of 50 children under 5 years of age, in nine of 122 older children, and in 19 of 230 adults. IgM antibodies were detected in nine children, but only in three adults. Past infection was indicated in six of 96 young children (aged 1–10 years), in 28 of 76 teenagers, and in 128 of 230 adults. Persistent infection was indicated in three young children, in six teenagers, and in 24 adults, with a significantly higher frequency (p = 0.012) in men (18 of 117) than in women (six of 113). No seasonal differences could be detected. Conclusions: Infection with C pneumoniae was detected serologically in children and adults without clinical signs of respiratory disease. These results should serve as a basis for studies on the role of C pneumoniae infections and their sequelae in Israel and contribute to the general understanding of asymptomatic infection with C pneumoniae.