All sexually active adolescent females should be tested by family doctors not once but twice a year for chlamydia infection, a significant preventable cause of pelvic inflammatory disease and infertility in women in the United States, say Johns Hopkins researchers.
Because the sexually transmitted infection caused by the bacterium Chlamydia trachomatis usually presents no obvious symptoms, the researchers say failure to test and treat with antibiotics during routine checkups is contributing to "the most important preventable cause" of infertility.
"Current guidelines for adolescent primary care call for yearly screenings, but that's not enough," says Gale Burstein, M.D., M.P.H. "Regardless of whether they've previously had sexually transmitted diseases, including chlamydia, or whether they've had a new sex partner or use condoms, these sexually active teenagers need more frequent testing."
In a study of 3,202 sexually active females age 12 through 19 who visited family planning, STD or school-based clinics in Baltimore, Md., 14-year-olds had the highest rate of infection with C. trachomatis.
Although most of the individuals were African-American, other, smaller studies have shown that white teenage females also have high rates of chlamydia, according to Burstein. "Infection rates among this group are generally above 5 to 10 percent in the populations that have been studied," she says.
"We couldn't predict which females in our study would be at increased risk for chlamydia just because they didn't use condoms consistently, or because they had a new sexual partner, or even because they previously had a sexually transmitted disease," says Burstein, a research fellow and adolescent medicine specialist at The Johns Hopkins University School of Medicine. "The only risk factor we found for chlamydia infection was being a teenager."
The Hopkins team also found they couldn't predict whether a female was infected just by determining whether she had symptoms, because chlamydia can occur as a "silent" infection without any obvious signs.
Burstein is the lead author of the study, which appears in the Aug. 12 issue of the Journal of the American Medical Association.
The study, funded by the Centers for Disease Control and Prevention, the Association of Teachers of Preventive Medicine STD Prevention Fellowship, and by the National Institutes of Health, used a new test that let researchers amplify chlamydia DNA in urine, eliminating the need for cervical samples, according to Thomas C. Quinn, professor of medicine and senior author of the paper.
"The ease of this procedure allows more women to be screened for chlamydia without a pelvic exam," he says. "And it lets us detect more infections even in women with silent--or asymptomatic--infections. Early detection can mean early treatment, which reduces complications and further spread of the infection."
The team found the organism in 771 females (24.1 percent) during their first visit to a clinic and in 299 (13.9 percent) during a repeat visit. A total of 933 (29.1 percent) had at least one positive test whether on their first visit to a clinic or on subsequent visits. The rate of infection was highest among 14-year-olds, with 63 of 229 (27.5 percent) who were screened testing positive.
"Using highly sensitive, urine-based DNA tests, we found that greater than fifty percent of those adolescent females who were infected tested positive for chlamydia within six to seven months into the study," says Burstein.
Other authors of the study include Charlotte A. Gaydos, Marie Diener-West, M. Rene Howell, and Jonathan M. Zenilman.
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