Objectives. Chlamydia trachomatis is the most prevalent bacterial sexually transmitted disease (STD) in the United States, with the highest rates reported among adolescents. Chlamydia has severe consequences including pelvic inflammatory disease and infertility, and is believed to be a cofactor in human immunodeficiency virus transmission. Given that chlamydia is predominantly asymptomatic, most cases are identified through routine screening in health care settings. Over time, screening and treatment appear to be associated with a decrease in the prevalence of disease in areas with consistent chlamydia control programs. The new availability of sensitive and specific urine tests for chlamydia (polymerase chain reaction [PCR] and ligase chain reaction [LCR]) provides the opportunity to screen large numbers of at-risk youth in a noninvasive manner. We used PCR/LCR testing to investigate the feasibility of a school-based chlamydia control program and to determine the prevalence of chlamydia infection among junior and senior high school students.
Design. At three junior/senior high schools, all students, regardless of symptoms or sexual history, were given the opportunity to be tested for chlamydia using urine-based PCR or LCR testing. Only students with parental consent were eligible. Parents could not obtain test results, except if their children told them. During the five 3-week testing periods, throughout the day, classes were escorted to the testing area and each student was individually counseled regarding the opportunity to participate in the testing.
Setting. Three urban public schools in Louisiana.
Participants. A total of 1933 students in grades 7 through 12, including 861 girls and 1072 boys.
Intervention. All students were informed about the test and taught about chlamydia during the homeroom period. Students were asked to provide a first-void urine specimen of not more than 30 mL. Specimens were refrigerated and delivered to the laboratory on the same day. Infected students were counseled and offered treatment with azithromycin, 1 g orally. They were also referred for or offered additional STD and human immunodeficiency virus testing. Infected students were asked to refer their sex partners to the city STD clinic for treatment.
Main Outcome Measure. Prevalence of C trachomatis infection by grade and gender.
Results. Parental consent was obtained for 2849 (86.9%) of the 3278 matriculated students in grades 7 through 12. Fifty-one parents (1.6%) returned consent forms refusing permission for their child to participate in this screening and treatment program. The remaining 378 (11.5%) could not be reached by mail or telephone. Among all students with consent, 1933 (67.8% of those consented and 59.0% of those matriculated) were tested. Girls were less likely to be tested than boys (861/1363 [63.2%] vs 1072/1465 [73.2%]).
The overall prevalence of C trachomatis was 6.5%, with rates among girls more than twice that of boys (9.7% vs 4.0%). Generally, rates of infection increased with age. The prevalence rates among boys were for 7th grade, 2/208 (1%); 8th grade, 2/196 (2%); 9th grade, 10/236 (4.2%); 10th grade, 12/185 (6.5%); 11th grade, 8/146 (5.5%); and 12th grade, 9/101 (8.9%). For boys 15 to 19 year old, the prevalence of chlamydia was 5.7%. Among girls, the prevalence rates were 7th grade, 0/105 (0%); 8th grade, 11/166 (6.6%); 9th grade, 23/218 (10.6%); 10th grade 23/146 (15.8%); 11th grade, 13/118 (11%); and 12th grade, 13/107 (12.1%). Among girls 15 to 19 years old, 12.7% were infected. Of 126 infected students, treatment was provided to 111 (88%).
For this project, the laboratory cost of LCR testing was $17.76 per test. Without considering clinical staff time to collect the specimens, the average laboratory cost per infected student identified was $272. For students 15 to 19 years of age, of whom 104 (8.9%) of 1170 were infected, the laboratory cost was $200 per case identified.
Conclusion. School-based chlamydia screening and treatment is feasible, acceptable, relatively inexpensive, and has a high yield. The higher prevalence among girls might be explained in part by greater incidence of symptoms among boys, prompting earlier diagnosis and treatment. Also, girls may have older, more experienced partners and may have greater exposure to chlamydia early in their sexual lives. The fact that girls are probably more susceptible to infection than boys could play a role as well.
DNA amplification technology as represented by PCR and LCR, the two types of tests currently available, offers the pediatrician who deals with adolescents greater flexibility in diagnosing chlamydia infections. Because the majority of chlamydia infections are asymptomatic and the disease can only be controlled through screening programs, urine-based screening may be the only practical way to accomplish this on a large scale. Schools are settings that can be used to reach the majority of adolescents.
Urine-based screening for chlamydia in school settings should be considered a routine part of programs to control STDs nationally. Because, over time, screening and treatment appear to be associated with a decrease in the prevalence of disease in areas with consistent chlamydia control programs, a national school-based chlamydia control program conceivably could lead to eradication of endemic C trachomatis in the United States.