A newly developed rapid test may help to improve detection rates of chlamydia, a common bacterial infection spread by sexual contact. A study published in the December issue of the British Medical Journal reported on the performance of the test in screening a large population of women for the disease. Researchers evaluated the new test with respect to molecular methods currently in use. As pointed out in the December 12, 2007 issue of Journal Watch Infectious Diseases, “this relatively low-cost test with good sensitivity and specificity and rapid turnaround time could be used in resource-limited settings. In any setting, it would allow same-day treatment of infected persons, thereby potentially limiting morbidity and spread of infection.” Though the test is not yet available for use in clinical settings in the U.S. or approved by the Food and Drug Administration, it may prove to be a useful tool in the screening for and early treatment of the most prevalent sexually-transmitted bacterial infection worldwide.

A new method for screening
The study looked at the ability of the new test to correctly identify infections caused by Chlamydia trachomatis. Researchers collected data from three separate clinics in the United Kingdom that screened 1349 women for the disease. They compared detection rates of the new immunoassay test with those of molecular tests, currently the standard method for detecting chlamydial infections. The rapid method recognizes markers from the bacteria (called lipopolysaccharides) in specimens that may be self-collected vaginal swabs or swabs collected by health care providers. This method can generate results within 30 minutes. Molecular methods often use first-void urine samples (women in the study often had to wait 2 hours before giving a urine sample). Molecular methods generate multiple copies of the bacteria’s genetic material if present (this step is called amplification) and then detect the presence or absence of the genetic material (DNA).

In evaluating the data from the study, the researchers found the new test to have acceptable sensitivity (83.5%) and good specificity (98.9%) compared with molecular testing. They also determined that women who participated in the study felt comfortable collecting samples themselves and that their specimens gave comparable results with specimens collected by doctors. With good reproducible results, ease of specimen collection, and same-day results, the new rapid method could lead to more frequent and improved screening for chlamydia. It may become another important way of limiting the spread of the most common sexually transmitted disease in regions of the world with fewer resources as well as in developed countries such as the US.

Reported cases continue to rise in U.S.
As in other areas of the world, the prevalence of sexually-transmitted diseases and specifically chlamydia continues to be of concern in the United States. According to a recent report by the Centers for Disease Control and Prevention (CDC), the incidence of chlamydial infections in the U.S. continues to grow. The 2006 STD Surveillance Report issued in December stated that the number of chlamydia cases topped 1 million, an increase of 5.6% over the previous year. A portion of the increase may due to greater awareness, more frequent screening, and improved technology for the detection of the disease, but the fact remains that chlamydia is a persistent public health problem.

Chlamydia is often called the “silent disease” because people who are infected often have no symptoms, do not seek treatment, and unknowingly spread the disease to others. If the infection goes untreated, it can cause pelvic inflammatory disease and lead to serious complications such as pelvic pain, infertility, and ectopic pregnancy. For these reasons, the CDC recommends that all women less than 26 years old be screened for the disease annually. The CDC report noted that effective screening programs may help to reduce complications resulting from the disease by as much as 60 percent.

Sources

S1
Mahilum-Tapay L et al. New point of care Chlamydia Rapid Test — Bridging the gap between diagnosis and treatment: Performance evaluation study.BMJ 2007 Dec 8; 335:1190.

S2
Baum S, New Rapid Test for Chlamydia. Journal Watch Infectious Diseases December 12, 2007. (online information, accessed December 2007). Available at: http://infectious-diseases.jwatch.org/cgi/content/full/2007/1212/6

S3
Rauscher M, US Rates of Chlamydia, Gonorrhea, Syphilis up in 2006: CDC Reuters Health Information (available online, accessed January 2008). Available at: http://www.medscape.com/viewarticle/565858

S4
Centers for Disease Control and Prevention: Sexually Transmitted Diseases Surveillance and Statistics, 2006 National Report, Chlamydia (online information, accessed December 2007). Available at: http://www.cdc.gov/std/stats/chlamydia.htm