National Overview of STIs in 2023

As in past years, there were significant disparities in reported STIs. In 2023, almost half (48.2%) of reported cases of chlamydia, gonorrhea, and syphilis (all stages) were among adolescents and young adults aged 15–24 years. Additionally, gay, bisexual and other men who have sex with men (MSM) are disproportionally impacted by STIs, including gonorrhea and primary and secondary (P&S) syphilis, and co-infection with HIV is common; in 2023, 37.2% of MSM with P&S syphilis were men diagnosed with HIV. In 2023, 32.4% of all cases of chlamydia, gonorrhea, and P&S syphilis were among non-Hispanic Black or African American persons, even though they made up only 12.6% of the US population. Rates of both P&S syphilis and congenital syphilis were highest among American Indian or Alaska Native persons in 2023.

It is important to note that these disparities are unlikely to be fully explained by differences in sexual behavior and may reflect differential access to quality sexual health care, as well as differences in sexual network characteristics. For example, in communities with higher prevalence of STIs, with each sexual encounter, people face a greater chance of encountering an infected partner than those in lower prevalence settings do, regardless of similar sexual behavior patterns. Acknowledging inequities in STI rates as well as their root causes is a critical first step toward empowering affected groups and the public health community to collaborate in addressing systemic inequities in the burden of disease — with the goal of minimizing the health impact of STIs on individuals and populations.

In 2023, 209,253 cases of syphilis (all stages including congenital syphilis) were reported which is the greatest number of cases reported since 1950 and an increase of 1.0% since 2022. There were:

• 53,007 cases of P&S syphilis (10.2% decrease compared to 2022),

• 53,573 cases of early non-primary non-secondary syphilis (5.9% decrease compared to 2022),

• 98,791 cases of unknown duration or late syphilis (12.8% increase compared to 2022), and

• 3,882 cases of congenital syphilis (3.0% increase compared to 2022).

Although the number of reported cases of syphilis (all stages) increased 1.0% when comparing 2023 to 2022, the rate of reported cases of syphilis per 100,000 persons was relatively stable (<1% change, 61.1 to 61.3 per 100,000); however, trends varied by stage of syphilis. From 2022 to 2023, the rate of P&S syphilis decreased 10.7%, which is the first substantial decrease in P&S syphilis since 2001. Rates of P&S syphilis decreased among men and women, most age groups, and all race/Hispanic ethnicities, and decreased in 41 states and the District of Columbia.

Concurrently, rates of unknown duration or late syphilis increased 12.2% (from 26.3 to 29.5 per 100,000). Cases of syphilis staged for surveillance as unknown duration or late syphilis reflect diagnoses that likely occurred after the infectious period (i.e., more than a year earlier) and are often identified through routine screening. Recent increases in cases staged as unknown duration or late syphilis may, in part, reflect delayed diagnosis of infections occurring during the COVID-19 pandemic when STI prevention and care services were disrupted.

In 2023, MSM accounted for one-third (32.7%) of all P&S syphilis cases, and 57.5% of P&S syphilis cases among men with known sex of sex partners. From 2022 to 2023, the number of P&S syphilis cases among MSM decreased 13.4%, representing the first substantial decrease in P&S syphilis among MSM in over 15 years. Decreases were observed among both HIV-negative MSM (8.5% decrease) and HIV-infected MSM (11.4% decrease).

In 2023, 3,882 cases of congenital syphilis were reported, including 279 congenital syphilis-related stillbirths and neonatal/infant deaths. This is the largest number of cases of congenital syphilis since 1992. The national congenital syphilis rate of 105.8 cases per 100,000 live births in 2023 represents a 3.0% increase relative to 2022. Although the majority of congenital syphilis cases were reported from a few states, in 2023, almost all jurisdictions (48 states and the District of Columbia) reported at least one case of congenital syphilis. From 2022 to 2023, rates of congenital syphilis increased in most race/Hispanic ethnicities and in 30 states.

Because perinatal transmission can occur during any stage of syphilis, increases in congenital syphilis often mirror increases in syphilis among reproductive aged women. From 2022 to 2023, the rate of syphilis (all stages) increased 6.8% among women aged 15–44 years, with increasing rates in 39 states and the District of Columbia.

In 2023, a total of 601,319 cases of gonorrhea were reported, making it the second most common nationally notifiable STI in the United States for that year. After reaching a historic low in 2009, rates of reported gonorrhea increased through 2021; however, the overall rate of gonorrhea decreased 9.2% from 2021 to 2022 and then decreased 7.7% from 2022 to 2023. From 2022 to 2023, rates decreased among men and women, most age groups, and most race/Hispanic ethnicities, and decreases were observed in 40 states. Decreases were most pronounced among women (14.1% decrease), reflecting substantial decreases among women aged 20 to 24 years (14.6% decrease) and aged 25 to 29 years (19.2% decrease), as well as among women diagnosed in non-sexually transmitted disease (STD) clinic settings (13.0% decrease). Because gonococcal infections can be asymptomatic, trends in case reports are influenced by both changes in incidence and screening coverage; recent declines in rates of reported gonorrhea may reflect declines in new infections, as well as reduced screening.

Since 2013, rates of reported gonorrhea have been higher among men compared to women, likely reflecting cases identified in both MSM and men who have sex with women only. Although there are limited data available on sexual behaviors of persons reported with gonorrhea at the national level, enhanced data from jurisdictions participating in a sentinel surveillance system, the STI Surveillance Network (SSuN), suggest that approximately half of gonorrhea cases occurred among MSM in 2023; however, this proportion varied across jurisdictions participating in SSuN.

In 2023, a total of 1,648,568 cases of Chlamydia trachomatis infection were reported, making it the most common nationally notifiable STI in the United States for that year. The rate of reported chlamydia in 2023 (492.2 per 100,000) was similar to the rate in 2021 (495.0 per 100,000). From 2022 to 2023, the rate of reported chlamydia increased among men (1.3%) and decreased among women (1.7%). Rates of reported chlamydia remain highest among adolescents and young adults and in 2023, 55.8% of all cases of chlamydia were reported among persons aged 15–24 years.

As chlamydial infections are usually asymptomatic, case rates are heavily influenced by screening coverage. During the COVID-19 pandemic, many health care clinics limited in-person visits to patients with symptoms or closed entirely, and preventive health care visits where STI screening usually happens, such as annual reproductive health visits for young women decreased. During 2020, the number of chlamydia cases decreased substantially, likely reflecting disruptions in STI-related care during the initial shelter in place orders. Although rates have increased since 2020, the national rate of reported chlamydia in 2023 is still lower than the rate in 2019, suggesting that reductions in chlamydia screening coverage may persist.