Chlamydia infection was detected during the 1997-1998 school year among 3% of male students in three Louisiana high schools where a program offering repeated screening and treatment for sexually transmitted diseases (STDs) had been introduced in 1995. By contrast, the prevalence rate was 6% among young men at five schools where an STD program was initiated only that year. The presence of an STD screening and treatment program was not associated with a similar decline in the rate of infection among female students.¹

The three schools that initially introduced the program were located in urban areas, had on-site health centers and had a total enrollment of about 2,200-2,500 students in grades 9-12 each year from 1995 through 1998; 52-65% of students participated in the program each year. The five schools that began the program in 1997 were demographically similar to the original three, but four of these did not have a school-based health center; the 2,652 students in these schools who obtained at least one STD test through the program served as a comparison group for studying the effect of repeated testing. All students in the original three schools were black, as were 98% of students in the comparison group. Approximately two-thirds of each group participated in a free or reduced-fee lunch program.

During the recruitment process, all students were educated about STDs and were encouraged to be tested, whether or not they were sexually active. Students could participate in the screening only if they had parental consent to receive services from the school-based health center or to obtain testing through the STD program. In the 1995-1996 school year, programs used urine tests to screen for chlamydia; in the 1996-1997 and the 1997-1998 academic years they also tested for gonorrhea. Students who tested positive for an infection were counseled and treated with antibiotics. Screening was offered twice annually during the first two years of the program and once during the third year. Researchers calculated prevalence and incidence rates of STDs according to the number of students who participated in testing. They also examined the prevalence of symptoms and students' likelihood of seeking STD services.

In all eight schools combined, the prevalence of chlamydia among students tested for the first time was 12% for young women and 6% for young men. A chlamydia diagnosis was more common among older students than among younger ones. For example, 9% of female ninth graders tested positive for chlamydia when first screened, compared with 14% of young women in grade 12. In grades 9-11, female students were approximately twice as likely to have chlamydia as their male counterparts.

Gonorrhea rates were also higher among young women than among young men. Overall, nearly 3% of young women tested positive for gonorrhea at their first STD test, compared with 1% of young men. Rates were similar among students in different grades (1-2% among male students and 2-3% among females).

Repeated STD screening was associated with a decrease in chlamydia prevalence among young men. During the third year of testing, the chlamydia rate was 3% among males in the schools where screening was offered repeatedly--half the rate in those schools at the start of the program and half the rate in the comparison schools. Gonorrhea prevalence among males was similar at all schools and at all points in the study (about 1%).

The chlamydia rate for women during the third year of testing was 10% at the original three schools, compared with 12% at the schools where STD screening had not initially been offered. The gonorrhea rate among women in the original group of schools declined from 3.3% during 1996-1997 to 1.8% during 1997-1998, differing only slightly from the rate of 2.1% among women at the comparison schools.

The combined incidence of chlamydia diagnoses in the three schools offering repeated testing varied over time from 6.6 to 11.4 new infections per 1,000 person-months for women and from 2.1 to 4.5 per 1,000 person-months for men. Ultimately, the incidence decreased for males between the first and fifth testings (from 4.5 to 2.8), while it increased for females (from 7.2 to 11.4). The incidence of gonorrhea, which was measured only three times, dropped from 1.1 to 0.4 infections per 1,000 person-months among males and from 5.1 to 2.5 per 1,000 person-months among females.

The majority of STD infections diagnosed by the screening programs were asymptomatic. Of those students with chlamydia or gonorrhea for whom researchers had information about symptoms, approximately 90% did not report a symptom. In the final year of testing at the original schools, 3% of students reported having had an STD symptom during the past year, and young women were more than twice as likely as young men to do so.

Among those with STD symptoms in the previous 12 months, 75% of male students and 85% of females had pursued treatment. Among students with no symptoms in the past year, 13% of males and 25% of females said they had been screened for an STD outside the school-based clinic. Young women who reported having been screened for an STD in the past year were about twice as likely to test positive for chlamydia or gonorrhea as were those who had not been tested (20% vs. 10%).

The researchers suggest that the successful implementation of the in-school STD screening and treatment programs was dependent on the support of individual principals and teachers, and that there can be financial barriers to replicating these programs on a wide scale. Further, the researchers note that some students may be having sexual intercourse with partners who are older than high school age and unreached by an in-school program, thus potentially compromising STD treatment. However, they contend that the "continued overall decline in prevalence and incidence [of chlamydia] among boys was very promising," and that "if the United States develops a national strategy to control chlamydia and gonorrhea in adolescents, school-based testing and treatment will be a critical component."--M. Moore

REFERENCE

1. Cohen DA et al., Repeated school-based screening for sexually transmitted diseases: a feasible strategy for reaching adolescents, Pediatrics, 1999, 104(6):1281-1285.