STI Quarterly

STI snapshot: Chlamydia leads in national rates — Young most at risk

Americans 15-24 at greatest risk of contracting the infection

According to a just-released analysis of the latest national sexually transmitted infection (STI) surveillance data, 1.4 million new cases of chlamydia were reported in the United States in 2011. This number corresponds to a rate of 457.6 cases per 100,000 population, an increase of 8% compared with the 2010 rate of 423.6.1

The rise in chlamydia cases is most likely due to increased screening, expanded use of more sensitive tests, and more complete national reporting, says the Centers for Disease Control and Prevention (CDC), which released the surveillance report. Seventy percent of the chlamydia cases reported in 2011 were in young adults ages 24 and below, the report notes.

While young men and young women are heavily affected by STIs, young women face the most serious long-term health consequences, the CDC report notes. Left untreated, diseases such as chlamydia and gonorrhea can negatively impact a woman's chance to have children later in life. The CDC estimates that undiagnosed STIs cause 24,000 women to become infertile each year.

The CDC advises annual screening for chlamydia in sexually active women ages 25 and under.2 However, results of a 2012 analysis, indicates 62% — more than 9 million young women — were not screened as recommended.3 The analysis examined data from the 2006-2008 cycle of the National Survey of Family Growth, a nationally representative household survey.

Public health officials also are keeping an eye on increasing rates of gonorrhea. A total of 321,849 cases were reported in 2011. This number corresponds to a rate of 104.2 per 100,000 people, reflecting a 4% increase since 2010. While infection rates remain at near-historic lows, CDC analysts note this is the second consecutive year of increases for the disease. A total of 62% of gonorrhea cases reported in 2011 were in those ages 24 and younger.1

Trend data reported for the first time this year show that primary and secondary (P&S) syphilis rates are increasing among men who have sex with men (MSM), who now account for nearly three-quarters of all infections, while declining among heterosexuals, notes Hillard Weinstock, MD, MPH, a CDC medical epidemiologist.

Our 'shared responsibility'

To truly address the increasing rates of syphilis among gay and bisexual men, the underlying conditions that place some at greater risk for STIs must be confronted, says Weinstock. "Every American has the ability to protect their own health; however, we also have a shared responsibility to tackle the root causes of these disparities," he notes.

While the data in the current report does not address why such increases are occurring, data from other research indicates that risk behavior alone does not explain the disproportionate levels of infection among gay and bisexual men, says Weinstock. Complex issues such as homophobia and stigma also can make it difficult for gay and bisexual men to seek appropriate care and treatment, he states.

A recent CDC analysis, comparing trends in P&S syphilis among MSM by age group and race/ethnicity, shows that sexual networks and a range of social and economic factors (higher rates of STIs, access to healthcare, etc.) place African American and Latino MSM at increased risk, notes Weinstock.4 Previous research also finds other factors, such as poverty, language, and legal barriers, might also play a role, he states.

An average of four in 10 men who have sex with men who are infected with syphilis also are infected with HIV, national surveillance data indicates.1 Syphilis infection can place a person at increased risk for HIV infection, or increase an HIV-infected person's viral load, according to the CDC. Given the high prevalence of HIV in the MSM community, increasing syphilis infections among men who have sex with men are particularly troubling, the agency notes.

Time to take action

What can clinicians do to stem the tide against rising infection rates? Getting more at-risk patients tested is a first step, say CDC officials. (See the boxed item below for CDC screening recommendations.)

Check CDC screening STI recommendations

  • Annual chlamydia screening for all sexually active women age 25 and under, as well as older women with risk factors such as new or multiple sex partners.
  • Yearly gonorrhea screening for at-risk sexually active women (e.g. those with new or multiple sex partners, and women who live in communities with a high burden of disease).
  • Syphilis, HIV, chlamydia, and hepatitis B screening for all pregnant women, and gonorrhea screening for at-risk pregnant women at the first prenatal visit, to protect the health of mothers and their infants.
  • Screening at least once a year for syphilis, chlamydia, gonorrhea, and HIV for all sexually active gay men, bisexual men, and other men who have sex with men (MSM). MSM who have multiple or anonymous partners should be screened more frequently for sexually transmitted infections (STIs) (i.e., at three- to six-month intervals). In addition, MSM who have sex in conjunction with illicit drug use (particularly methamphetamine use) or whose sex partners participate in these activities should be screened more frequently.

Source: Centers for Disease Control and Prevention. Sexually transmitted diseases treatment guidelines, 2010. MMWR 2010; 59(No. RR-12).

"Too many people – including men who have sex with men – are unaware of their infection," says Weinstock. "In addition to disparities among MSM, we also find that youth are particularly affected by STIs and bear the highest rates of gonorrhea and chlamydia."

Clinicians can help bring the "hidden epidemic" of STIs into the spotlight, says Weinstock. Many Americans are reluctant to discuss sexual health issues, though STIs are very common, he notes. Clinicians can aid in bringing these conversations out of the shadows, Weinstock states.

The CDC offers a "Let's Talk About Sexual Health" video to highlight the importance of a healthy dialogue between youth and providers concerning their sexual health. Produced by "Be Smart. Be Well," the video is a joint effort of Blue Cross and Blue Shield of Illinois, Blue Cross and Blue Shield of New Mexico, Blue Cross and Blue Shield of Oklahoma, and Blue Cross and Blue Shield of Texas. The video features CDC Epidemiologist Elizabeth Torrone, PhD, MSPH. (Access the video at Under "What's New," select "Let's Talk About Sexual Health.")

Also, providers can take tips from a 2012 CDC podcast offered by Gail Bolan, MD, director of the CDC's Division of STD Prevention, to help boost STI awareness among youth. (To access the podcast, go to On the left side of the page, select "Publications & Products," "Videos & Podcasts," then "STD Awareness — Reaching Youth.") It is important to build and maintain a culture of privacy and confidentiality for your adolescent patients in setting the stage for STI talks, she noted.

Bolan calls for clinicians to discuss the five "Ps" with their patients:

  • partners;
  • practices;
  • protection from STIs;
  • past history of STIs;
  • pregnancy prevention.

Be sure to encourage STD testing among sexually active young people, says Bolan.

Everyone has a role to play in the fight against STIs, notes Weinstock. Clinicians should talk to their patients about testing and assess their patients' risk for STIs and test them accordingly, while individuals should talk openly with their doctor and partners about STIs and testing, he asserts. MSM who are sexually active should be tested at least annually for STIs and HIV.

Discuss that consistent condom use and mutual monogamy also can decrease risk, says Weinstock. Talk with patients about such web sites as and the CDC's toll-free number, 800-CDC-INFO, to get more information on testing.

"Community leaders can use family-centered approaches ensuring that parents are educated about STDs [sexually transmitted diseases] and are able to talk to their children and teenagers about the facts and STD prevention," Weinstock advocates. "They can also help by speaking out about STDs and fighting stigma."


  1. Centers for Disease Control and Prevention. Sexually Transmitted Disease Surveillance 2011. Atlanta: U.S. Department of Health and Human Services; 2012.
  2. Workowski KA, Berman S; Centers for Disease Control and Prevention. Sexually transmitted diseases treatment guidelines, 2010. MMWR 2010; 59(RR-12):44.
  3. Tao G, Hoover KW, Leichliter JS, et al. Self-reported Chlamydia testing rates of sexually active women aged 15-25 years in the United States, 2006-2008. Sex Transm Dis2012; 39(8):605-607.
  4. Su JR, Beltrami JF, Zaidi AA, et al; Primary and secondary syphilis among black and Hispanic men who have sex with men: case report data from 27 states. Ann Intern Med 2011; 155(3):145-151.