Prevalence of antibodies to Chlamydia trachomatis in Japanese persons determined by microimmunofluorescence using reticulate bodies as single antigen.

The incidence of humoral antibodies to Chlamydia trachomatis was determined in 1005 Japanese individuals of various ages. Formalin-fixed purified reticulate bodies of C. trachomatis (L2(434) strain) were used as antigens in the microimmunofluorescence test. Of 137 pregnant women, 25 (18.2%) had antibody titers of 1:10 or larger. Of 120 cord blood specimens from newborns, 16 (13.3%) were positive. Among 565 infants and children a progressive, age-related increase in seropositivity was observed except in 6- to 8-year-olds: 9.2% for infants under 1 year old; 20.8 to 25.0% for 1-to 5-year-olds; 11.7 to 17.6% for 6- to 8-year-olds; and 26.1 to 32.3% for 9- to 15-year-olds. Among 183 adults the seropositivity rate was between 20.0 and 26.7%, and a progressive increase in seropositivity was not clearly observed. These data suggest that C. trachomatis infection occurs commonly in Japanese adults and children.