Do infants increase the risk of re-emergent infection in households after mass drug administration for trachoma?

PURPOSE Mass treatment with azithromycin for trachoma endemic communities typically excludes infants under age 6 months, whose parents are provided with tubes of tetracycline to administer daily over 4 to 6 weeks. The authors sought to determine whether infants aged <6 months are a source of re-emergent infection in their families after mass treatment in trachoma-endemic communities. METHODS In a longitudinal study of all children aged less than 10 years in four communities, the authors identified 91 infants aged <6 months living in 86 of 1241 households. All children aged <ten years in all households were examined for trachoma and ocular infection with C. trachomatis at baseline, and 6 months after mass drug administration. RESULTS The prevalence of infection at baseline in the infants was 5.9%. At 6 months post mass drug administration, the rate of infection among children older than 6 months and less than 10 years who resided in households with infants was 6.0% compared with 11.1% in children in households without infants (P = 0.18). After adjustment for age, sex, baseline infection status, and treatment, residing in a household with an infant was not associated with infection at 6 months (odds ratio [95% confidence interval] 0.50 [0.20-1.22]). CONCLUSIONS This prospective study did not find evidence that living in a household with an infant increased the risk of infection 6 months post mass drug administration in other children residing in the household.