Then why are most Americans unfamiliar with it? For one thing, the bacterium that causes chlamydia could not be easily isolated and studied until 1965. "The bugs couldn't be grown in the laboratory, and people don't want to work with things that are difficult," says Julius Schachter, an epidemiologist at the University of California, San Francisco. Then, too, the presence of chlamydial infections until recently could be detected only by a complicated laboratory test that took up to seven days to complete and was offered at few medical centers in the U.S. As a result, chlamydia was rarely diagnosed. Says Dr. Ward Cates Jr., head of the CDC's division of sexually transmitted diseases: "Most physicians went to medical school when it was not recognized, and would have trouble spelling it, much less treating it."
In addition, chlamydia's signs are sometimes subtle and easily misinterpreted. Men with chlamydia can experience a burning sensation during urination and a mucoid discharge, but their illness is often diagnosed as gonorrhea. In women, chlamydia may also mimic gonorrhea, causing a vaginal discharge, or result in the frequent and sometimes painful urination associated with a urinary-tract infection.
When doctors confronted with chlamydial symptoms mistakenly prescribe penicillin, the usual treatment for gonorrhea, or order the drugs most commonly used for urinary-tract infections, the chlamydial infection rages on. Repeated doses of the antibiotics tetracycline or erythromycin over a period of one week are required to knock out the bug.
If the wrong drugs are used for chlamydia or if it is left untreated, the infection can spread throughout the reproductive tract. In men, it generally / leaves no lasting effects, though many continue to harbor the bacteria and can infect their sexual partners. In women, the bacteria may travel through the uterus into the fallopian tubes, which become inflamed and eventually scarred. While the infection in some cases causes severe lower abdominal pain, thus sending a clear danger signal, the symptoms in other women are barely noticeable. Many of these women remain unaware of their infection. Only after trying unsuccessfully to become pregnant do they discover that their fallopian tubes have been blocked by scar tissue.
Even when the scarring is not severe enough to cause sterility, it can prove troublesome. It can cause a fertilized egg, normally implanted in the uterus, to become embedded and begin dividing in a fallopian tube, leading to a potentially life-threatening condition known as tubal or ectopic pregnancy. Since 1967 the incidence of ectopic pregnancy in the U.S. has tripled. According to Dr. King Holmes, chief of medicine at Harborview Medical Center in Seattle, chlamydia may be a factor in at least one-quarter of the cases.
Women who contract chlamydia during a normal pregnancy face yet another serious problem: transmitting the disease to their babies, who are infected while passing through the birth canal. In infants, chlamydia manifests itself in the form of conjunctivitis, an inflammation of the eye, or as pneumonia. There is also some evidence, Holmes says, that chlamydial infection during pregnancy increases the risks of premature and stillborn births.
Because chlamydia is easy to treat once it is diagnosed, the key to preventing its spread--and its sometimes serious consequences--is better detection. That could be provided by two recently developed diagnostic tests that are both inexpensive and rapid. One, called MicroTrak, has been marketed for a year by the Syva Co. of Palo Alto, Calif., and provides a diagnosis in less than half an hour. The other, devised by Abbott Laboratories of North Chicago, Ill., takes from 3 1/2 to four hours but is better suited for testing large numbers of people. It became available nationwide last week.
Chlamydia is so widespread that some doctors have begun administering the appropriate antibiotics to suspect patients even before the results of diagnostic tests are in. For example, because 40% of women and 20% of men with gonorrhea also have chlamydia, the CDC's Cates recommends that anyone with a confirmed case of gonorrhea be treated for chlamydia as well. Schachter suggests the same policy for women with PID. "You can't just sit around and wait for a lab diagnosis," he says. "The patient could wind up sterile."
Alarmed by the spread of the disease, Washington State's King County, which includes Seattle, last December allocated $120,000 for a community-wide chlamydia-screening program. Says the county health department's Dr. Hunter Handsfield, who heads the effort: "The problem nationwide is that chlamydia is an out-of-sight, out-of-mind phenomenon." Only when more public health officials recognize and face up to it, he says, will the silent epidemic be brought under control.