Curing chlamydia: new screening test and one-dose drug

The price of sex

Chlamydia is the most common bacterial (and thus curable) sexually transmitted disease in the United States, by far, ahead of gonorrhea and syphilis. It is caused by the Chlamydia trachomatis bacteria and transmitted during vaginal, oral or anal sexual contact with an infected partner.

"Far and away, the age group most affected are the 15- to 19-year-olds," says Hitchcock. Studies show that young adults in Lange's age group, 20 to 24, are the second most affected group.

Wearing a condom may help reduce the risk of contracting chlamydia, but "protected" sex with a condom can't completely prevent transmission of chlamydia or some other STDs, though experts recommend consistent condom use to reduce the chances of getting an STD.

Symptoms of chlamydia

When they occur, symptoms of chlamydia 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 may also 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 Centers for Disease Control and Prevention (CDC) estimates that in up to 40 percent of cases chlamydia can lead to pelvic inflammatory disease, a serious infection of the woman's fallopian tubes that can also damage the ovaries and uterus leading to infertility. It's not known whether chlamydia infection causes fertility problems or other long-term consequences in men.

Simple screening and treatment

Because so many people are at risk for chlamydia and the disease can ravage a woman's reproductive system without so much as a symptom, experts recommend regular, widespread screening to detect the disease.

The old way

• Traditional methods of screening require a health professional to collect a swab sample of genital secretions. For women, this can be done as part of a pap smear with little or no 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, 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.

The new ways

Today, a number of tests are available to supplement or replace the relatively expensive and slow traditional culture. The three major types of nonculture tests are:

• Direct fluorescent antibody test (DFA)
• This test uses a scientific method called staining to make chlamydia easier to spot under a microscope. DFA can give quicker results than culture and can be performed on specimens taken from the eye, cervix or penis.
• Enzyme immunoassays
• This test comes in some forms that can be used in small, unsophisticated laboratories that don't have special lab equipment. Because testing can be done where the specimen is collected, results are more rapid than with culture, access to testing is increased, and costs can be lower.
• Tests to detect the genes of C. trachomatis in urine and genital samples
• These tests can accurately identify even very small numbers of genes in a specimen. These tests can be expensive, but are becoming more popular among public and other labs because of their accuracy and the relative ease of collecting urine samples.

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."

Should you get tested?

The CDC 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:

• are less than 25 years old
• don't use barrier contraceptives consistently
• have new or multiple sex partners
• have signs of a possible cervical infection
• have previously had an STD

"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, a chlamydia researcher at Johns Hopkins University. She and other chlamydia experts have recently questioned whether that is even enough.

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, Burstein says. "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."

New medication: a one shot deal

Lange and her boyfriend both took the antibiotic azithromycin (Zithromax), a prescription drug approved by the 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.

Is a vaccine next?

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 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.