The sexually transmitted disease chlamydia usually comes with no telltale symptoms, so most people don't even know when they are infected. But left untreated, the so-called "silent epidemic" of chlamydia threatens to cause reproductive damage and infertility in many of the 3 million to 4 million Americans who get it each year. "Chlamydia's consequences can be devastating," says Diane Mitchell, M.D., an obstetrician-gynecologist and medical reviewer with the Food and Drug Administration.
Routine chlamydia screening and early, effective treatment are the keys to reducing chlamydia's toll, according to Penny Hitchcock, chief of the National Institutes of Health's sexually transmitted disease branch. Two recent medical advances, she says, constitute "very important breakthroughs" in controlling the rampant disease: a new drug treatment recently approved by FDA to cure chlamydia in a single oral dose, and a urine-based screening test that, unlike other tests, does not require a swab sample of cells from the genital area.
Caused by the Chlamydia trachomatis bacteria and transmitted during vaginal, oral or anal sexual contact with an infected partner, chlamydia is the most reported bacterial infection in the United States and the most common bacterial (and thus curable) sexually transmitted disease by far, ahead of gonorrhea and syphilis.
A person can become infected at any age, but "it's adolescents that we're most worried about," Hitchcock says. "Far and away, the age group most affected are the 15- to 19-year-olds. If you're sexually active and you're in that age group, you're at risk." Studies show that young adults in Lange's age group, 20 to 24, are the second most affected group.
While wearing a condom may help reduce the risk of chlamydia, anyone who is sexually active can get the disease. (See "Condoms and Chlamydia.")
Symptoms of chlamydia, when they occur, usually appear within one to three weeks of exposure. In women, signs can include unusual vaginal discharge or bleeding, burning during urination, or lower abdominal pain. Men, like women, may have pain during urination, or they may notice a burning and itching around or discharge from the penis or pain and swelling in the testicles.
More often, though, chlamydia lives up to its reputation for silence. Experts estimate that up to 75 percent of women and 50 percent of men with chlamydia have no symptoms or symptoms so mild that they don't seek medical attention.
Chlamydia is "a very insidious disease," says Hitchcock. "Because it rarely causes symptoms, people don't know they're infected. So they don't get treated, and they infect their partners, who also don't get treated."
Without treatment, the national Centers for Disease Control and Prevention estimates, chlamydia can lead in up to 40 percent of cases to pelvic inflammatory disease, a serious infection of the woman's fallopian tubes that can also damage the ovaries and uterus. (See "A Threat to Fertility.") Also, women infected with chlamydia may have three to five times the risk of getting infected with HIV if exposed, according to CDC.
It's not known whether chlamydia infection causes fertility problems or other long-term consequences in men. "We are worried -- though we don't have a lot of evidence -- that chlamydia infection could cause chronic problems in men," Hitchcock says. "But as far as we know, the biggest price is paid by young women."
Babies sometimes pay a price, as well. Babies who are exposed to chlamydia in the birth canal during delivery can be born with pneumonia or an eye infection called conjunctivitis, both of which can be dangerous unless treated early with antibiotics.
Because so many people are at risk for chlamydia and because the disease can ravage a woman's reproductive system without so much as a symptom, experts recommend regular, widespread screening to detect the disease. (See "Should You Get Tested?")
Traditional methods of screening require a health professional to collect a swab sample of genital secretions. For women this type of test "minutely prolongs" a pap smear, FDA's Mitchell explains. "At worst, it can feel like a tiny menstrual cramp, but most women don't experience any discomfort." Male samples are obtained by inserting a swab into the end of the penis.
In the past, the sample had to be "cultured" in a laboratory to look for C. trachomatis, and it could take three days or more for results to become available. Also, accuracy of results could vary greatly based on the lab staff's level of expertise and experience.
Today, a number of tests are available to supplement or sometimes replace the relatively expensive and slow traditional culture. The three major types of nonculture tests are:
No one screening method is best, Leone says. "It's a tradeoff. We're constantly balancing what is the cheapest test with what is the most sensitive, what is easiest to get from the patient versus what will pick up the most infections."
At Leone's clinic, Lange was tested using the enzyme immunoassay method. She doubted the results at first, Leone says. "We explained to her that yes, the test was accurate, and she really needed to be treated even though she had no symptoms."
Lange and her boyfriend both took the antibiotic azithromycin (Zithromax), a prescription drug approved by FDA in 1997 to cure chlamydia in one dose. "It's a breakthrough because we can observe therapy rather than depending on people to adhere to a more complicated regimen," Hitchcock says. Doxycycline (sold under several brand names), the other antibiotic approved and commonly used to treat chlamydia, is generally taken twice a day for seven days.
Widespread chlamydia screening among women can get results, as was demonstrated in a recent study supported by NIH. Researchers at Seattle's Group Health Cooperative of Puget Sound and the University of Washington found that symptomless women who were screened and treated for chlamydial infection were almost 60 percent less likely than unscreened women to develop pelvic inflammatory disease.
With such effective tools for screening and treatment, why has it proved so difficult to stop the spread of this microorganism? The answer, experts agree, is that not enough at-risk young people are getting tested.
"There are about a million reasons people don't get tested," Mitchell says. "They might feel uncomfortable, or not have insurance, or just not know they should be tested for chlamydia."
Also, doctors often fail to discuss the issue of sexually transmitted diseases with their young patients, according to Gale Burstein, M.D., a chlamydia researcher at Johns Hopkins University. "Physicians have to make a commitment to ask all of their adolescent patients if they are sexually active. But doctors are sometimes uncomfortable pursuing that line of questioning," Burstein says, adding that "a sexually active adolescent woman is more likely to test positive for chlamydia than for tuberculosis, yet TB tests are done much more routinely."
Beyond encouraging more young people to get routinely screened for chlamydia, experts are searching for other avenues to control this sexually transmitted disease. Recently, researchers at Stanford University and the University of California at San Francisco uncovered new information about the chromosomes of C. trachomatis, providing promising leads for developing new antibiotics and even a vaccine. Hitchcock, whose agency supported the study, says she and other STD experts at NIH are "very excited about the new opportunities for vaccine development."
Until the hope of a vaccine is realized, those who choose to be sexually active should use condoms -- for what they're worth. "Condom use clearly prevents HIV infection and gonorrhea, as well as pregnancy," Hitchcock says. "Use a condom, but not with blinders on, either. Don't kid yourself that condoms make sex risk-free."
Tamar Nordenberg is a staff writer for FDA Consumer.
Condoms and Chlamydia
The only sure-fire way to avoid getting chlamydia and other sexually transmitted diseases is by abstaining from sex or being in a mutually monogamous relationship with an uninfected partner. Having multiple partners increases your risk of getting the disease, according to experts.
Anna Lange was especially surprised when she was diagnosed with chlamydia because, besides not having any symptoms, she had been in a monogamous relationship for six months. "We explained to her that the diagnosis didn't mean that either she or her current boyfriend had been unfaithful," says Peter Leone, M.D., medical director at Anna's STD clinic. "We couldn't tell her when or from whom she'd gotten infected. But she did have a history of unprotected sex for a couple of years previously, and she could have become infected at any time during this period."
While even "protected " sex with a condom can't completely prevent transmission of chlamydia or some other sexually transmitted diseases, experts recommend correct and consistent condom use to reduce the chances of getting chlamydia or other STDs.
Should You Get Tested?
The national Centers for Disease Control and Prevention recommends annual chlamydia screening for all sexually active adolescent girls and for other females who may be at high risk for chlamydial infection, such as those who:
"Females who are at risk because of their age and sexual activity need to get screened at least once a year," says researcher Gale Burstein, M.D. She and other chlamydia experts have recently questioned whether that is even enough.
Based on a study they conducted in 1998, Burstein and her colleagues at Johns Hopkins University recently recommended a twice-yearly screening of sexually active female adolescents. In tracking more than 3,000 sexually active Baltimore high school girls for three years, they found that more than a quarter of them tested positive for chlamydia at least once in that time frame.
Routine screening is recommended for pregnant women, also, because of the risk that their babies will become infected with chlamydia at birth.
There are no recommendations for routine screening among males, which Burstein says makes it especially likely that their chlamydial infection will be overlooked. "There is a lot of chlamydia in men that we're missing, and they are a major reservoir of infection. We're really only putting a band-aid on the problem because, even if we're screening the women, some are going back to their partners and getting reinfected."
Another Chlamydia Making Headlines
The Chlamydia trachomatis bacteria that cause the sexually transmitted disease should not be confused with Chlamydia pneumoniae. These other bugs, which can cause colds and pneumonia, have been in the news because investigators are researching their possible link with atherosclerosis, a clogging of the arteries that causes most heart attacks and strokes. Add this type of chlamydia to smoking, a bad diet, and a sedentary lifestyle as possible contributors to heart disease.
Pelvic inflammatory disease is caused when the C. trachomatis bacteria move from the cervix (where they enter during sexual intercourse) to the uterus and fallopian tubes, in some cases scarring the tubes enough to make fertilization impossible.
"These women may never be able to have children," says Penny Hitchcock, an expert in sexually transmitted diseases, "unless the problem can be surgically corrected, which is uncommon and expensive."
Even if the fallopian tubes are not completely blocked, scarring can interfere with the passage of the fertilized egg into the uterus. A blocked egg may instead implant in the fallopian tube, creating an ectopic or tubal pregnancy, which endangers the mother's life and results in loss of the fetus.