Epidemiology of ocular chlamydial infection in a trachoma-hyperendemic area.

The epidemiology of ocular chlamydial infection in a trachoma-hyperendemic area of Tanzania was investigated. Specimens for chlamydial isolation cultures and direct fluorescent antibody cytology were collected from 1085 children aged 1-7 years. Other data included examinations for signs of clinical trachoma and the collection of household data on risk factors. A total of 33% of children had a positive laboratory test for Chlamydia species. The most important factors for predicting chlamydial infection were the presence of a sibling with laboratory evidence of infection, increased number of flies around the house, a household that herded cattle, and practice of a local religion. Younger children and girls were at no increased risk for a positive laboratory test, although these subgroups have more clinical disease. The data are compatible with a model of less frequent episodes of reinfection as children become older.