NONOCULAR CHLAMYDIA INFECTION AND RISK OF OCULAR REINFECTION AFTER MASS TREATMENT IN A TRACHOMA HYPERENDEMIC AREA

Purpose. The presence of nasal discharge on a child's face increases the risk of active trachoma, suggesting that Chlamydia trachomatis in nasal secretions may be a possible source of ocular reinfection. The prevalence of chlamydia in nasal secretions and the risk of reinfection after mass treatment was investigated in a hyperendemic area of Tanzania. Methods. In one village a total of 232 children aged 1 to 7 years were followed before and after mass treatment. Clinical trachoma, and microbiologic evidence of chlamydia, were assessed at baseline, 2 and 4 weeks into mass treatment, and 4 weeks after treatment stopped. The presence of chlamydia in ocular and nasal secretions was determined by polymerase chain reaction-enzyme immunoassay techniques. Results. Of the 232 children, 59% had clinical trachoma and 27% had nasal specimens positive for chlamydia. Children with positive ocular chlamydia specimens and/or clinical trachoma were significantly more likely to have positive nasal specimens. At the end of mass treatment, only 4% of children had positive ocular specimens. However, 1 month after treatment stopped, the incidence of new infection was 2 1%. The rate of new ocular infections in those who had-negative ocular specimens after treatment was similar between those who had positive and those who had negative nasal specimens at baseline. Positive ocular specimens at baseline was not a predictor of risk of new infection after treatment (odds ratio = 1. 18, 95% confidence interval = 0.58, 2.40), suggesting these new infections were not the result of latent or persistent organism. Conclusions. These data do not support a role for nasal secretions in causing reinfection after treatment. One mass topical treatment alone is unlikely to be effective in trachoma hyperendemic areas as shown by the rapid re-emergence of infection.