Prevalence of Chlamydial antibodies in children

V. H. San Joaquin, P. J. Rettig, J. Y. Newton and M. I. Marks

Humoral antibody to Chlamydia trachomatis was determined in 820 infants and children. Of 120 newborns, 63 (52.5%) had indirect immunofluorescence titers of 1:8 or more to C trachomatis (L-2 strain) in the cord blood. Among the 700 infants and children, a progressive increase in seropositivity was observed: 5% for 1- to 2-years-olds, 25% for 3- to 6-year-olds, and 43% for 7- to 15-year-olds. Seropositivity rates were not related to sex or race; however, significantly higher titers were observed in female compared with male subjects and in blacks compared with whites. These data suggest that C trachomatis infection occurs commonly in children. The nature of the illness, if any, preceding seroconversion is unknown and needs to be elucidated.