A study published in the Sept. 10, 1998, issue of The New England Journal of Medicine suggests that age is the best criterion on which to base a screening program for chlamydial infection in women military recruits. In a study of 13,204 women recruits, the overall prevalence of infection was 9.2 percent, with a peak of 12.2 percent among the 17-year-olds who volunteered for the study.
"The study showed that a screening program for all women 25 years of age or younger would have identified 95.3 percent of infected women," says senior author Thomas Quinn, M.D., of the Laboratory of Immunoregulation at the National Institute of Allergy and Infectious Diseases (NIAID), and the Division of Infectious Diseases at the Johns Hopkins University.
Such programs are possible because of the new DNA amplification tests called ligase chain reaction (LCR) assays. LCR assays are based on technology similar to the older, more familiar polymerase chain reaction (PCR) assays. The sensitivity of LCR has made it possible to screen for chlamydial infection using only a urine sample with up to 95 percent accuracy.
"More than 4 million Chlamydia trachomatis infections occur each year, many in women, and often without symptoms," comments NIAID Director Anthony S. Fauci, M.D. "With improved, simpler and accurate screening methods, health care professionals can reach more people with silent infections and prevent the consequences of chlamydial disease: pelvic inflammatory disease, tubal scarring, infertility and ectopic pregnancy."
"Although the LCR tests are slightly more expensive than traditional nonculture tests," says Dr. Quinn, "the savings associated with not performing a pelvic examination, the enhanced ability to detect infections and to prevent pelvic inflammatory disease, plus the advantage of using urine as the diagnostic specimen all outweigh the extra cost of the LCR test."
In the current study, researchers found several risk factors independently associated with chlamydial infection: having ever had vaginal sex (93.1 percent); being 25 years of age or less (87.9 percent); having had more than one sex partner in the previous 90 days (26.7 percent); having had a new partner in the previous 90 days (31.4 percent); having had a partner in the previous 90 days who did not always use a condom (83.1 percent); and having ever had a sexually transmitted disease (STD). Of the volunteers who reported ever having had an STD, 9.1 percent had been diagnosed with chlamydia; 3.3 percent had had gonorrhea; 0.6 percent had had syphilis; and 4.6 percent had had a trichomonas infection.
Ethnicity was also a factor. Among black recruits, prevalence of chlamydial infection was 14.9 percent; for whites, the prevalence was 5.5 percent; and for all other ethnicities, the total prevalence was 8.1 percent.
In addition, there was a geographic variation in prevalence of infection. More than 15 percent of the recruits from five southern states - South Carolina, Georgia, Alabama, Louisiana and Mississippi - tested positive for chlamydia. The states with the lowest incidence, less than 5 percent, were Washington, Oregon, Minnesota, Arizona and Massachusetts.
The investigators also documented a 1.4 percent rate of chlamydial infection among the 914 volunteers who denied being sexually active, and an 8.4 percent rate among those who reported that their partners consistently used condoms. "These data," says Dr. Quinn, "underscore the wisdom of screening based on age rather than on self-reported sexual behavior."
In addition to Dr. Quinn, authors are: Charlotte A. Gaydos, Dr.P.H., M. Rene Howell, M.S., and Barbara Pare, M.S., all of the Division of Infectious Diseases, Johns Hopkins University, Baltimore, Md.; Kathryn L. Clark, M.D., M.P.H., of the Walter Reed Army Institute of Research, Washington, D.C.; Joel C. Gaydos, M.D., M.P.H., of the Walter Reed Army Institute of Research, Washington, D.C., and the Henry M. Jackson Foundation, Rockville, Md.; Dorothy A. Ellis, B.S.N., M.P.H., and Rose Marie Hendrix, D.O., M.P.H., both of the United States Army Medical Activity, Fort Jackson, S.C.; and Kelly T. McKee, Jr., M.D., M.P.H., of the Womack Army Medical Center, Fort Bragg, N.C. The study was also supported by a grant from the Department of the Army.
NIAID is a component of the National Institutes of Health (NIH). NIAID conducts and supports research to prevent, diagnose and treat illnesses such as HIV disease and other sexually transmitted diseases, tuberculosis, malaria, asthma and allergies. NIH is an agency of the U.S. Department of Health and Human Services.
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