Only 38 percent of the 16 million American women aged 15 to 25 who are sexually active were screened for chlamydia in the prior year, putting them at risk for chronic pain, life-threatening pregnancies and infertility, US health experts said on Tuesday. Chlamydia is the most commonly reported sexually transmitted disease in the United States, with 1.3 million new cases reported to the US Centers for Disease Control and Prevention in 2010. But because the infection often has no symptoms, the actual rate of new infections may be more than twice that, or nearly 2.8 million new infections each year, Dr. Gail Bolan, the CDC’s director of STD Prevention, told reporters in a conference call from the National STD Prevention Conference in Minneapolis. If caught early, chlamydia is easily cured with antibiotics. That’s why the CDC recommends annual screening for all sexually active women and retesting three months after treatment for those found to be infected. But according to studies presented at the meeting, many women are not following these recommendations. “The new data make it clear we are missing far too many opportunities to protect young women,” Bolan told the briefing. In one study presented at the meeting, Karen Hoover of the CDC studied data from 2006 to 2008 taken from a nationally representative survey. She found that 38 percent of young women aged 15 to 25, or more than 9 million young women who were sexually active in the prior year, were screened for chlamydia as recommended. Testing rates were higher, however, among certain groups, including among women aged 20 to 25, 42 percent of whom had been tested; black women, 55 percent of whom had been tested, and those who had multiple sexual partners, with 47 percent saying they had been tested in the prior year. Even when women are tested, however, they often do not get retested to make sure they have not been reinfected by a sexual partner. According to an analysis by Kelly Morrison Opdyke of Cicatelli Associates, a non-profit group that trains health and social service workers, lab data on more than 63,000 men and women in New York, New Jersey and the US Virgin Islands found that just 11 percent of men and 21 percent of women were retested within six months of being treated for chlamydia. Untreated chlamydia infections can spread into the uterus or fallopian tubes and cause pelvic inflammatory disease. Undetected infections in the upper genital tract can damage the fallopian tubes, uterus, and surrounding tissues, causing chronic pain, infertility and potentially fatal ectopic pregnancies, in which the egg implants in the fallopian tubes. And like other sexually transmitted diseases, chlamydia may also make a woman more vulnerable to HIV infections if exposed. “It is critical that health care providers are not only aware of the importance of testing sexually active young women every year for chlamydia infections, but also of retesting anyone who is diagnosed,” Bolan said in a statement.