Sexually transmitted infections are quite common in the United States (U.S.), and rates have increased steadily, with millions of new infections occurring yearly. According to a recent Centers for Disease Control and Prevention surveillance report on STIs, over 2 million chlamydia, gonorrhea, and syphilis cases were reported in 2020.

This article reviews the latest statistics on the most common STIs and discusses how to reduce your risk.

How Many People Have STIs?

In 2018, the CDC estimated that one in five people in the U.S., or 20% of the population, had a sexually transmitted infection (STI). These STIs include chlamydia, gonorrhea, syphilis, hepatitis B, herpes simplex virus type 2, human immunodeficiency virus (HIV), human papillomavirus (HPV), and trichomoniasis.

Most Common STIs

Chlamydia, gonorrhea, and syphilis are the most commonly notifiable sexually transmitted infections in the U.S. Though HIV is more common than gonorrhea or syphilis, it is often considered its own category of disease.

Chlamydia

Chlamydia was the most common notifiable STI in the U.S. in 2020. It is most prevalent among adolescents and young adults between 15 and 24 and transmitted through oral, vaginal, or anal sex, as well as passed from an infected mother to a baby during childbirth.

Chlamydia is often asymptomatic; when symptoms are present, it’s usually five to 14 days after infection. Symptoms of chlamydia include:

Abnormal dischargeBurning when peeing Pain or swelling of the testicles (in men)

Symptoms of a rectal chlamydia infection include:

Pain DischargeBleeding

Chlamydia is a treatable STI; your healthcare provider can prescribe medicine and monitor for repeated infection. If left untreated, chlamydia can cause permanent damage to women’s reproductive organs and make it more challenging for them to get pregnant.

Gonorrhea

The second most common notifiable STI in the U.S. is gonorrhea, which can cause infection in the genitals, rectum, and throat. Young people ages 15 to 25 are disproportionately affected. Like chlamydia, it’s transmitted through oral, vaginal, or anal sex and can be passed down during childbirth. 

Gonorrhea is often asymptomatic. Symptoms of gonorrhea, when present, include:

Pain or burning when peeing Vaginal discharge and bleeding between periods (in women)White, yellow, or green penile discharge (in men)Painful or swollen testicles (in men)

Symptoms of gonorrhea in women may be confused with a bladder or vaginal infection.

Symptoms of rectal gonorrhea infection include:

DischargeItchingSorenessBleedingPain during bowel movements 

Gonorrhea can lead to health complications if left untreated; women can develop pelvic inflammatory disease, and men can develop pain and potential infertility. Gonorrhea is treatable; a healthcare provider can prescribe medicine to cure the infection. 

Syphilis

Syphilis is the third most common notifiable STI in the U.S., with rates increasing nearly every year since 2001. Syphilis spreads through contact with syphilis sores during vaginal, anal, or oral sex.

A mother can also spread syphilis to her baby during pregnancy, which is called congenital syphilis. In 2020, 149 stillbirths and infant deaths were attributed to congenital syphilis.

Syphilis has four stages: primary, secondary, latent, and tertiary; symptoms vary by stage. Syphilis stages include:

Primary stage: One or more sores in, on, or around the penis, vagina, anus, rectum, and lips or mouth  Secondary stage: Skin rash or sores in the mouth, vagina, or anus, rough, red, or a reddish-brown rash most commonly in the palm of the hands or bottoms of the feet (but can appear anywhere), fever, swollen lymph glands, sore throat, patchy hair loss, headaches, weight loss, muscle aches, and fatigue Latent stage: No visible symptoms Tertiary stage: Can affect organ systems, but most people do not develop this stage

Syphilis is treatable with antibiotics. Left untreated, syphilis can affect the brain, nervous symptoms, eyes, or ears.

STI Statistics

The below statistics represent the STI surveillance data collected during COVID-19 in 2020. Health authorities advise interpreting the data cautiously, as the pandemic has affected screening and data collection.

Chlamydia

1. 6 million cases of chlamydia were reported, a 13% decrease from 201961% of all cases were among adolescents and young adults (15 to 24 years old)

Gonorrhea

677,769 cases of gonorrhea were reported, a 5. 7% increase from 2019

Syphilis

133,945 cases of syphilis and 2,148 congenital syphilis were reported, up 6. 8% and 15% from 2019

STI Prevention

All sexually transmitted infections are preventable and treatable, and some are curable. Testing can help with timely treatment and prevent spreading the infection to others.

Over half (53%) of reported cases of STIs in 2020 were among adolescents and young adults aged 15 to 2432% of all cases of chlamydia, gonorrhea, and primary and secondary syphilis were among non-Hispanic Black populations

It is important to note that these disparities are not reflective of sexual behaviors but access to quality sexual health care and other systemic inequities.

The Importance of Prevention

STI rates are increasing and adolescents, young adults, and men who have sex with men are at an increased risk. Additionally, having a sexually transmitted infection places people at a higher risk for HIV.

Prevention can avoid irreversible health complications, including:

Reproductive problems Fetal and perinatal complicationsCancerFacilitation of HIV transmission

How to Prevent STIs

There are several ways to prevent STIs, including:

Abstinence from vaginal, oral, and anal sex Vaccination to prevent hepatitis and HPV  Reducing your number of sexual partners  Regularly getting tested and sharing results with sexual partners Using male, latex condoms or female condoms correctly and consistently during oral, anal, and vaginal sex  Practicing monogamy (a long-term, mutually exclusive relationship with one partner) 

Summary

Rates of sexually transmitted infections (STIs) are rising in the U.S., especially among adolescents and young adults. Individuals with STIs like chlamydia and gonorrhea can be asymptomatic, so taking measures to prevent contracting and spreading STIs is important.

STIs are preventable and treatable but may lead to serious complications if left untreated. 

A Word From Verywell

If you have concerns or think you may have symptoms of an STI, talk to your healthcare provider about getting screened. All STIs are treatable, and many are curable. Early treatment can avoid further complications in the future.