Repeat Infections with Chlamydia Trachomatis in High Schools

Background: In clinical populations, the rates of reinfection with sexually transmitted pathogens are high.

Objectives: To determine Chlamydia trachomatis reinfection rates among high school students who were not seeking care in clinical settings.

Methods: Between 1995 and 2005, 7950 students in an urban US high school district were were tested for C trachomatis more than once in an annual school-wide screening using urine DNA amplification tests. Among them, 1500 received at least one one positive test, including 793 who were retested at least once after testing positive. Students testing positive were treated with 1g azithromycin orally under direct observation. Among students retested after testing positive, the rate of reinfection was calculated among 521 (males, 182; females, 339) for whom the date of treatment for their chlamydial infection was known. For students who consecutively tested positive, reinfection was estimated to have occurred half-way between the date of treatment and the following positive test. For students with non-consecutive positive tests, reinfection was estimated to have occurred half-way between their most recent negative test and the following positive test.

Results: Of the 521 students retested after being treated for chlamydia, 47 males and 113 females became reinfected. The repeat infection rate was 26.8/100 person-years (males, 23.5/100 person-years; females, 28.4/100 person-years). The median time between treatment and repeat infection was 5.7 months (males, 6.5 months; females, 5.6 months). 

Conclusions: Adolescent students treated for chlamydia in a school-wide screening program had reinfection rates as high as or higher than shown in high-risk individuals diagnosed and treated for chlamydia in clinical settings.

Implications for Programs, Policy, and/or Research:Adolescents treated for chlamydia as part of high school screening programs should be retested periodically to maximize population benefits of the program. Greater access to STD screening in high schools should be a public health priority in the US.