How Can You Test For Chlamydia ?

Chlamydia cultures have only been widely available in Canada since the mid 1980's. Unfortunately, this type of cell culture is expensive, labour intensive and time consuming. However, this culture, (if performed in a reliable lab) is still the most sensitive test for chlamydia. It takes three to four days to complete. It should ideally be used for screening low risk groups, such as university students or women with only one steady sexual partner. Practically speaking, this culture is not widely available due to expense.

About eight years ago two other screening tests were put on the market. These other tests are quicker and less expensive but not as accurate as the cell culture test. In the first test the direct fluorescent antibody test (DFA), a specially prepared slide is examined under the microscope for EB's. In the second test the ELISA test (enzyme-linked immunoabsorbent assay) the presence of chlamydia is measured using a colour meter.

Both tests are only 75 to 80 percent accurate in detecting chlamydia. This means there can be both false negatives and false positives. A false positive can cause a lot of havoc in a relationship. If you have a positive test, and you are in a low risk group, you should remember that a positive test indicates a heightened risk rather than proving conclusively that you have chlamydia. Also chlamydia can be carried for a long time, certainly more than a year, and the infection could have been acquired in the past and gone unrecognized.

A false negative can cause chlamydia to go untreated and be passed on to other people. Dr. James McSherry, Medical Director of Student Health Services in Kingston, Ontario, feels that these two tests still have an unacceptably high false negative rate.

He feels that it makes sense to treat contacts of people with chlamydia infections even without taking cultures, certainly whether cultures are positive or not.

Both tests are constantly being improved, so these tests may become more accurate in the future.

The DFA test can also be used to test urine (urinary test kits for chlamydia are now available in larger cities). Because of their low sensitivity, urine tests are probably only useful to confirm infection in men who have symptoms. So far the urine tests have not been very valuable as a screening test.

However, a completely new approach for urinary testing is being developed that is much more sensitive; it can measure tiny DNA fragments of the chlamydial cell wall. This testing method is not yet widely available. However, it may end up being useful for testing both men and women who have no symptoms.

Who Is At Risk For Chlamydia ?

Studies of risk profiles show the highest risk if you are under 24, have had a new sex partner within six months and are using no birth control or a non-barrier method of birth control.

When doctors say that sexually active women with many partners are at risk for chlamydia, what this means for all practical purposes is that any woman who has had more than one sexual partner, or whose sexual partner has had more than one sexual partner is at risk.

If you have just been diagnosed with herpes, gonorrhea or another sexually transmitted disease, you have a 30 to 60 percent chance of also having chlamydia.

Says Dr. McSherry, "Widespread use of the pill has set the scene for wholesale spread of chlamydia." The pill causes changes in the cervix that make it more susceptible to chlamydia infection as well as other sexually transmitted diseases. In addition, Dr. Richard Boroditsky, a Winnipeg gynecologist and researcher, points out that breakthrough bleeding while on the pill may be caused by chlamydia and easily missed.

Protecting Yourself

Condoms afford the best protection against chlamydia as well as against gonorrhea, herpes, venereal warts and AIDS. The diaphragm and cervical cap do provide more protection against chlamydia than the pill, but it is not yet certain that their level of protection is as high as the condom.

However, a new study of women with sexually transmitted diseases conducted in Denver, Colorado, showed that women who used diaphragms (or cervical caps) had 65 percent less gonorrhea and 72 percent less chlamydia compared to women who used no birth control.