Serological evidence of the three chlamydial species in an aboriginal community in the Northern Territory.

Abstract

OBJECTIVE: To determine the pattern of seropositivity to the three species of Chlamydia in women and children from a single community. DESIGN: Testing of blood samples obtained during a prospective study of mothers and infants. For each individual, the sample giving the highest titre of antichlamydial antibody was included in the analysis. SETTING: The only health centre for a small rural community in the Top End of the Northern Territory. This served all 1200 or so residents, almost 95% of whom were Aboriginal. PARTICIPANTS: Sixty-one pregnant Aboriginal women at routine antenatal clinic visits, and 114 of their children aged between one and six years at the time of sampling. MAIN OUTCOME MEASURE: Specific IgG or IgM antibody to any of the three species of Chlamydia at titres > or = 32, as determined by micro-immunofluorescence. RESULTS: IgG antibody to one or more chlamydial species was found in 83.6% of mothers and 42.1% of their children. IgM antibody was found in five mothers and four children, in each case against only one chlamydial species. IgG antibody to C. trachomatis was found in 55.7% of mothers and 28.9% of children, to C. pneumoniae in 59.0% of mothers and 19.3% of children, and to C. psittaci in 29.5% of mothers and 17.5% of children. Log linear modelling gave positive correlations between seropositivity for C. trachomatis and C. pneumoniae (chi 2 = 9, P < 0.01), and for C. trachomatis and C. psittaci (chi 2 = 15, P < 0.001). Cross-reactivity was more evident in children than in mothers. CONCLUSIONS: This is the first Australian report providing serological evidence of exposure to the three chlamydial species in one community. The seropositivity patterns suggest complex interactions when all species are present.