Narrator: This is Science Today. Chlamydia is our most common sexually transmitted disease. Dr. Julius Schacter of the University of California, San Francisco says there about four million cases a year in the U.S. Most men and some women have symptoms, so it gets treated.

Schacter: But many of these women actually with chlamydial infections have no signs or symptoms of the disease, and that is the horror story here...

Narrator: ...because undiagnosed chlamydia can lead to sterility and ectopic pregnancy. But a new test recently evaluated by Schacter may help prevent that.

Schacter: In the past, to diagnose chlamydial infection required collecting a swab from the involved anatomic site. This was usually the urethra in men and the cervix in females. But what's happened now is we have found that you can diagnose chlamydial infection from men or women by testing urine specimens.

Narrator : Which means that more infections will be found and treated before it's too late. For Science Today, I'm Steve Tokar.