Rates of chlamydia, gonorrhea, and syphilis went up in 2016, the third year in a row, according to the Centers for Disease Control and Prevention’s recently released annual report on sexually transmitted diseases. 

In total, more than 2 million cases of these three bacterial STDs were reported in the U.S. last year, the highest number ever, according to the CDC report. A majority of the cases—1.6 million—were chlamydia.

Chlamydia infections rose by 4.7 percent in one year, gonorrhea by 18.5 percent, and syphilis by 17.6 percent.

More on STDs

While these conditions can usually be cured with antibiotics, according to the CDC, if left untreated they can lead to serious health consequences, including pelvic inflammatory disease, infertility, stillbirth, and increased risk of HIV transmission.

A question that’s arisen is whether the CDC statistics reflect a true escalation in infections.

Better reporting may play a role, notes Philip Chan, M.D., an assistant professor of medicine at Brown University and medical director at the Rhode Island STD Clinic at The Miriam Hospital in Providence. “But a lot of us suspect there is a real increase as well.”

What might be causing a genuine increase isn't clear at this point. People could be using fewer condoms and having more partners, says Chan, who adds that researchers don’t yet have a lot of evidence that condom use is falling.

As we await additional data, here's what to know to protect yourself and those you love from STDs.

Who Is at Risk

Anyone who has sex can be at risk for an STD, but the chances are higher for those who have multiple sex partners and don’t practice safe sex, says Tamika Auguste, M.D., an obstetrician-gynecologist and associate professor at Georgetown University in Washington, D.C.

According to a statement by Gail Bolan, M.D., the CDC’s director of STD prevention, that accompanied the report, people age 15 to 24 made up most of the reported chlamydia and gonorrhea infections. About half of all new cases of STDs occur in people 15 to 24, the report found. And one in four sexually active adolescent females has an STD.

This group is also experiencing increases in syphilis, Auguste says. That's a concern, in part because mothers with syphilis can pass on the disease to their babies during pregnancy. While this remains rare, the 628 cases reported in the CDC report mark a 27.6 percent increase since 2015. These cases led to 40 deaths and severe complications in newborns.

Health experts are also concerned about gay and bisexual men of all ages. The CDC report found that a majority of the new cases of syphilis occur in men who have sex with men.

How to Stay Safe

Given that STDs sometimes have no symptoms, people who are sexually active should be screened annually, Chan says.

When it comes to specific STDs, the CDC advises that everyone between the age of 13 and 64 be tested for HIV at least once and at least yearly if they have risk factors.

For chlamydia and gonorrhea, the CDC recommends annual screening for all sexually active women under age 25 and for women 25 and older who have new or multiple sex partners, or a sex partner with an STD.

Pregnant women should be screened for HIV and syphilis, and for chlamydia and gonorrhea if they are at risk for those conditions. For men who have sex with men, the CDC recommends screening at least once a year for chlamydia, gonorrhea, and syphilis.

And if you think you've aged out of risk factors, think again. Auguste says she is seeing more STDs in older women. “Even if you think ‘I’m not in one of those traditional age groups that has to be worried about this,’ people need to get tested," she says, "especially if you have a healthy sex life.” Ask new partners about their testing history, too.

Consider these five additional steps as well:

  • Use condoms when it's appropriate; they can reduce the risk of STDs, including HIV.
  • Protect younger people. Have them get vaccinated against the human papillomavirus (HPV) infection. And take note of what the CDC’s March 10 Morbidity and Mortality Weekly Report said about rules allowing children to stay on their parents’ health insurance until age 26: “Although these provisions likely facilitate access to the healthcare system, adolescents and young adults might not seek care or might delay seeking care for certain services because of concerns about confidentiality, including fears that their parents might find out.”
  • Be honest with your doctor. It’s important to discuss your behavior—and your partner's—with your healthcare practitioner, says Auguste, so he or she can give you proper advice. “We’re all human,” she notes. “There may be slipups.”
  • Go to a doctor or health clinic for testing if you suspect an STD. While STDs often have no visible signs, at least initially, you may experience symptoms such as pain and/or a burning sensation when urinating, a fever, or swollen glands. Skip drugstore and online tests for diagnosing STDs because they’re unreliable, Chan says.
  • Get treated properly. If you are diagnosed with chlamydia, gonorrhea, or syphilis, your doctor will prescribe antibiotics. Make sure your partners are treated, too, the CDC says. Because some strains of gonorrhea are becoming resistant to the antibiotics that have traditionally been used to treat them, most medical experts currently recommend a two-drug approach: ceftriaxone plus azithromycin.