LONGITUDINAL-STUDY OF THE MICROBIOLOGY OF ENDEMIC TRACHOMA

Abstract

A longitudinal study of trachoma in 100 members of nine Tanzanian families was conducted to assess the sources of variation in the laboratory identification of trachoma and the changes that might occur over time. Multiple conjunctival swabs were collected every 3 months for 1 year and examined by direct fluorescent-antibody cytology (DFA), enzyme immunoassay, or microimmunofluorescence serology for tear antichlamydial antibodies. DFA specimens collected 5 min apart had a discordance rate of 10% and this is attributable to sampling variation. DFA specimens collected 2 days or more apart show a 25% discordance rate. This suggests a biologic variation in shedding in addition to sampling variati..