STI Statistics 2026: Rates, Trends & Most Common STDs

Sexually transmitted infections (STIs) remain a major global health concern, affecting millions of people every year. The World Health Organization (WHO) estimates that more than 1 million curable STIs are acquired every day worldwide, while infections such as HPV and genital herpes affect hundreds of millions of people. 

In the United States, recent data show a mixed picture. Reported cases of some major STIs have declined, but the overall burden remains high compared with a decade ago. STI statistics also vary by infection, age, sex, and region, making it important to look beyond reported case numbers alone. 

This article examines the latest STI statistics and trends, including global infection estimates, U.S. case numbers, common STIs, age and demographic patterns, testing, and prevention.

Key STI Statistics at a Glance

• Over 1 million curable STIs are acquired every day worldwide.
• WHO estimated 374 million new cases of chlamydia, gonorrhea, syphilis, and trichomoniasis worldwide in 2020.
• An estimated 846 million people aged 15 to 49 were living with genital herpes worldwide in 2020.
• More than 42 million Americans are living with disease-associated HPV infections.
• Approximately 13 million new HPV infections occur in the U.S. each year.
• CDC estimated 26.2 million new STI infections in the U.S. in 2018.
• People aged 15 to 24 accounted for 45.5% of estimated new U.S. STI infections.
• The U.S. reported approximately 1.52 million chlamydia cases in 2024.
• Congenital syphilis cases in the U.S. were nearly 700% higher in 2024 than a decade earlier.
• The EU/EEA gonorrhea notification rate increased by 303% between 2015 and 2024.

General STI/STD Statistics

374 Million New STI Cases Occur Worldwide Each Year

More than 1 million curable sexually transmitted infections (STIs) are acquired every day worldwide. In 2020, the World Health Organization (WHO) estimated 374 million new infections from four major curable STIs: 156 million cases of trichomoniasis, 129 million cases of chlamydia, 82 million cases of gonorrhea, and 7.1 million cases of syphilis. 

Source: World Health Organization

The global burden also includes viral STIs, with more than 520 million people estimated to be living with genital herpes in 2020 and approximately 300 million women living with HPV infections. In addition, WHO estimates that 254 million people were living with chronic hepatitis B in 2022, highlighting the scale of the global STI burden beyond the four commonly reported curable infections.

26.2 Million New STI Infections Were Estimated in the U.S.

The CDC’s most comprehensive estimates of new infections across eight major STIs are based on 2018 data. They estimated 26.2 million new STI infections in the United States that year. 

HPV accounted for the largest number, with an estimated 13.0 million new infections, followed by trichomoniasis at 6.9 million, chlamydia at 4.0 million, gonorrhea at 1.6 million, genital herpes at 572,000, and syphilis at 146,000. These figures are estimates of infections, not 2026 case counts, and they should not be compared directly with annual reported surveillance totals.

Source: CDC Stacks

1.51 Million Chlamydia Cases Were Reported in the U.S. in 2024

Chlamydia is the most frequently reported bacterial STI in the United States. CDC surveillance recorded 1,515,985 reported cases in 2024, down from 1,648,568 in 2023, an 8% decrease. The 2024 rate was 445.7 cases per 100,000 people. 

However, reported cases represent diagnosed infections rather than the total number of infections. CDC’s 2018 modeling estimated approximately 4.0 million new chlamydia infections, showing the large gap between estimated infections and reported diagnoses.

Source: CDC 

543,409 Gonorrhea Cases Were Reported in the U.S. in 2024

The United States reported 543,409 gonorrhea cases in 2024, compared with 601,319 in 2023. This represents a decline of about 10% in one year and marked the third consecutive annual decrease. 

Despite this decline, the number of reported cases remains substantial. CDC previously estimated approximately 1.6 million new gonorrhea infections in 2018, again showing that reported cases capture only a portion of total infections.

The trend in Europe has been very different. EU/EEA countries reported 106,331 confirmed gonorrhea cases in 2024, the highest notification rate since European STI surveillance began in 2009. The notification rate increased by 303% between 2015 and 2024.

190,242 Syphilis Cases Were Reported in the U.S. in 2024

Syphilis remains a major global STI concern. WHO estimates that 8 million adults aged 15 to 49 acquired syphilis in 2022, compared with 7.1 million estimated new infections in 2020.

In the United States, reported syphilis cases rose sharply during the early 2020s before declining in 2024. There were 190,242 reported syphilis cases in 2024, compared with 209,249 in 2023, representing a decrease of about 9%. However, congenital syphilis continued to increase, with nearly 4,000 reported cases in 2024, marking the 12th consecutive annual increase.

Source: CDC

Overall, these statistics show why reported STI cases should not be treated as the full number of infections. Infections that are frequently asymptomatic or not routinely reported can account for millions of additional cases.

U.S. Congenital Syphilis Cases Reached 3,941 in 2024

Congenital syphilis occurs when syphilis is transmitted from a pregnant person to their baby during pregnancy. In the United States, reported cases have increased steadily over the past several years.

Source: CDC

The United States reported 3,941 congenital syphilis cases in 2024, up from 2,168 cases in 2020. This represents an increase of approximately 82% in four years. CDC reported that 2024 marked the 12th consecutive year of increases, with cases nearly 700% higher than a decade earlier. The rise continued even as reported primary and secondary syphilis cases declined in 2024.

The increase is also a global concern. WHO estimated that approximately 1.1 million pregnant women had syphilis in 2022, contributing to more than 390,000 adverse birth outcomes worldwide. These outcomes include stillbirth, neonatal death, prematurity, and other serious complications.

HPV Statistics

42 Million Americans Are Living With Disease-Associated HPV

Human papillomavirus (HPV) is one of the most common sexually transmitted infections in the United States. CDC estimates that more than 42 million Americans are living with a disease-associated HPV infection. Detailed CDC modeling estimated that 42.5 million people aged 15 to 59 had at least one HPV type associated with HPV-related cancers, precancers, or genital warts in 2018.

13 Million New HPV Infections Occur Each Year

CDC estimates that approximately 13 million new disease-associated HPV infections occur in the United States each year. In its 2018 analysis, CDC estimated that 13 million people acquired a new disease-associated HPV infection.

HPV Accounts for Nearly Half of New STI Infections

HPV represented a major share of the estimated U.S. STI burden in 2018. Of the 26.2 million new infections across eight major STIs, approximately 13 million were HPV infections, meaning HPV accounted for about 50% of all estimated new infections in the analysis.

HPV Vaccination Helps Prevent HPV-Related Diseases

HPV vaccination can prevent infections with HPV types that cause many HPV-related cancers and other diseases. Vaccination, together with recommended screening, plays an important role in reducing the long-term health impact of HPV infections.

Genital Herpes Statistics

846 Million People Were Living With Genital Herpes in 2020

Genital herpes is a major global STI, affecting hundreds of millions of people. WHO estimates that approximately 846 million people aged 15 to 49 were living with genital herpes worldwide in 2020. This means more than 1 in 5 people in this age group had a genital herpes infection.

42 Million New Genital Herpes Infections Occur Each Year

WHO estimates that approximately 42 million people acquire a new genital herpes infection each year worldwide. The high number of new infections reflects the widespread transmission of herpes simplex viruses globally.

572,000 New HSV-2 Infections Were Estimated in the U.S. in 2018

In the United States, CDC estimated approximately 572,000 new genital HSV-2 infections among people aged 15 to 49 in 2018. This figure represents HSV-2 infections specifically and does not capture all cases of genital herpes.

HSV-2 Estimates Do Not Include All Genital Herpes Cases

Genital herpes can be caused by both HSV-1 and HSV-2. Therefore, the U.S. estimate of 572,000 new HSV-2 infections does not represent the total number of new genital herpes infections. Genital infections caused by HSV-1 can also contribute to the overall burden.

Trichomoniasis Statistics

156 Million New Trichomoniasis Infections Occurred Worldwide in 2020

Trichomoniasis is one of the most common curable sexually transmitted infections (STIs), but it receives less attention than chlamydia and gonorrhea because it is not routinely included in U.S. national STI surveillance. 

WHO estimated 156 million new trichomoniasis infections worldwide in 2020 among people aged 15 to 49. This made trichomoniasis the most common of the four curable STIs included in WHO’s global estimates.

6.9 Million New Trichomoniasis Infections Were Estimated in the U.S. in 2018

CDC modeling estimated approximately 6.9 million new trichomoniasis infections among people aged 15 to 59 in the United States in 2018. The same analysis estimated that about 2.6 million people were living with the infection at a given time. Because many infections cause no symptoms, routine reporting does not capture the full number of infections.

Trichomoniasis Is the Most Common Nonviral STI

WHO identifies Trichomonas vaginalis as the most common nonviral STI. Of the estimated 156 million new global infections in 2020, approximately 82.6 million occurred in males and 73.7 million in females aged 15 to 49.

STI Trends Over Time

STI trends vary by infection, country, and time period, so there is no single global pattern of cases simply rising or falling. Recent U.S. surveillance shows a decline in several major bacterial STIs, but the longer-term trend remains higher than it was a decade ago.

U.S. Reported Chlamydia, Gonorrhea and Syphilis Cases Declined in 2024

In the United States, reported cases of the three nationally notifiable STIs chlamydia, gonorrhea, and syphilis fell from approximately 2.53 million cases in 2021 to 2.25 million in 2024, a decline of about 11%. The decrease was driven mainly by lower numbers of reported gonorrhea and chlamydia cases in 2024.

U.S. STI Cases Remained 13% Higher Than a Decade Earlier

Despite the recent decline, the long-term U.S. trend remains concerning. CDC reported that the combined number of reported chlamydia, gonorrhea, and syphilis cases in 2024 was 13% higher than in 2014. Congenital syphilis showed an even larger increase, with reported cases nearly 700% higher than a decade earlier.

Gonorrhea Increased 303% in the EU/EEA Between 2015 and 2024

Europe has experienced a stronger increase in several bacterial STIs. Between 2015 and 2024, the EU/EEA gonorrhea notification rate increased by 303%, reaching its highest level since European surveillance began in 2009. Syphilis notification rates also more than doubled during the same period.

Overall, the data show a mixed STI trend: U.S. reported cases have declined recently, while the longer-term burden remains elevated and several European countries have recorded substantial increases in gonorrhea and syphilis.

STI Statistics by Age

Age is a major factor in STI statistics, with younger people accounting for a disproportionately large share of new infections in the United States. CDC modeling estimated that people aged 15 to 24 accounted for 45.5% of all new STI infections, despite making up a much smaller share of the total population. The concentration was particularly high for chlamydia and gonorrhea.

Young People Accounted for 45.5% of New STI Infections

CDC’s comprehensive U.S. incidence estimates found that people aged 15–24 accounted for nearly half (45.5%) of all estimated new STI infections. The proportion varied considerably by infection.

66.5% of New Chlamydia Infections Occurred Among Young People

Chlamydia showed the strongest concentration among younger people. CDC estimated that approximately 2.6 million new chlamydia infections occurred among young people, representing 66.5% of all estimated new chlamydia infections.

55.8% of Reported Chlamydia Cases Were Among 15 to 24-Year-Olds

Routine surveillance shows a similar pattern. In finalized U.S. data for 2023, people aged 15–24 accounted for 55.8% of all reported chlamydia cases. This highlights the particularly high burden of chlamydia among adolescents and young adults.

Overall, the statistics show that young people carry a disproportionately large share of the U.S. STI burden, particularly for chlamydia, gonorrhea, and HPV.

STI Statistics by Sex and Demographic Group

STI rates vary by sex, age, sexual behavior, screening practices, and the type of infection. The pattern is different for each STI, with some infections more frequently reported among women and others more common among men.

Women Accounted for 62% of Reported Chlamydia Cases in 2024

In the United States, women accounted for approximately 943,890 reported chlamydia cases in 2024, compared with 564,489 cases among men. Women therefore represented about 62% of reported cases, while men accounted for about 38%. This difference is partly influenced by screening practices, as CDC recommends routine chlamydia screening for sexually active women under age 25.

Men Accounted for 63% of Reported Gonorrhea Cases in 2024

Gonorrhea showed the opposite pattern. CDC recorded approximately 341,667 reported cases among men and 198,932 among women in 2024. Men therefore accounted for about 63% of reported gonorrhea cases, compared with approximately 37% among women.

Men Had More Than Six Times the Syphilis Notification Rate in Europe

Syphilis has a particularly high burden among men, including gay, bisexual, and other men who have sex with men (MSM). In the EU/EEA, the 2024 syphilis notification rate among men was more than six times higher than among women. 

Men aged 25 to 34 had the highest rate, at approximately 46 cases per 100,000 people. Among cases where the transmission category was known, 69% occurred among MSM.

Syphilis Notifications Are Also Rising Among Heterosexual Populations

The increase in syphilis is not limited to MSM. ECDC reported sustained increases in syphilis notifications among heterosexual men and women across adult age groups since 2021. This suggests that the recent European syphilis increase is affecting multiple demographic groups.

Overall, the statistics show that sex and demographic patterns differ substantially by STI. Chlamydia is more frequently reported among women, while gonorrhea and syphilis have higher reported rates among men. Differences in screening, sexual networks, symptoms, and access to testing can also influence these patterns.

STI Statistics by Country and Region

Comparing STI rates between countries requires caution because testing, screening, reporting systems, and surveillance quality differ widely. A country with broader testing may report more infections than a country with limited testing, even when the underlying level of infection is similar.

EU/EEA Reported STI Cases in 2024

Surveillance data from the European Centre for Disease Prevention and Control (ECDC) show a substantial burden of bacterial STIs across the EU/EEA in 2024.

Among countries with consistent reporting, chlamydia notification rates decreased by about 10% between 2023 and 2024, while the gonorrhea rate increased by 4.3%.

England Reported 8,262 Infectious Syphilis Diagnoses in 2025

England recorded 8,262 infectious syphilis diagnoses in 2025, down from 9,553 in 2024. This represents a 13.5% decrease in one year.

Among gay, bisexual, and other men who have sex with men, diagnoses declined by 18.7%, from 6,349 in 2024 to 5,164 in 2025. However, diagnoses among heterosexual and bisexual women who have sex with men increased by 4.8%, from 838 to 878 cases during the same period.

STI Testing Statistics and Recommendations

STI testing has a direct effect on reported case numbers. More testing can lead to more diagnosed and reported infections, even when the actual level of transmission has not increased. Expanded screening can identify infections that would otherwise remain undiagnosed, making reported case numbers a combination of infection levels and detection levels.

Annual Chlamydia and Gonorrhea Testing Is Recommended for Sexually Active Women Under 25

CDC recommends annual chlamydia and gonorrhea screening for all sexually active women younger than 25. Women aged 25 and older should also be tested when they have factors that increase their risk of infection.

Annual STI Testing Is Recommended for Sexually Active MSM

CDC recommends that sexually active gay and bisexual men and other men who have sex with men (MSM) receive testing for syphilis, chlamydia, and gonorrhea at least once a year. People with higher-risk sexual activity, including multiple or anonymous partners, may benefit from testing every 3 to 6 months.

Syphilis Testing Is Recommended During Pregnancy

Pregnancy is another important opportunity for STI screening. CDC recommends syphilis testing at the first prenatal visit. Pregnant people who have an increased risk of syphilis should receive additional testing later in pregnancy.

Many STIs Produce No Symptoms

Testing is particularly important because many STI infections do not cause noticeable symptoms. A person can therefore have and transmit an infection without knowing it. Regular screening helps identify infections earlier and allows treatment to reduce complications and further transmission.

STI Prevention Methods That Reduce Infection Risk

No single prevention method eliminates the risk of every STI. The strongest approach combines regular testing, vaccination, correct condom use, timely treatment, and safer sexual practices. CDC recommends using several of these strategies together to reduce the risk of infection and transmission.

• Regular STI Testing Helps Detect Undiagnosed Infections: Many STIs can cause few or no noticeable symptoms, so people may not know they are infected. Testing based on age, sexual activity, and individual risk factors can identify infections that might otherwise go undiagnosed.
• Condoms Reduce the Risk of Many STIs: Using condoms correctly and consistently can reduce the risk of transmitting or acquiring many STIs. However, protection is not the same for every infection because condoms provide less coverage for infections that can spread through skin-to-skin contact outside the area covered by the condom.
• Vaccination Can Prevent HPV and Hepatitis B: Vaccination provides effective protection against some sexually transmitted infections. HPV vaccination helps prevent infections that can cause genital warts and several types of cancer, while hepatitis B vaccination can prevent hepatitis B virus infection.
• STI Testing During Pregnancy Can Prevent Serious Outcomes: Testing during pregnancy is particularly important for syphilis because untreated maternal infection can be transmitted to the baby. Early diagnosis and treatment can reduce the risk of congenital syphilis, stillbirth, and other serious complications.
• Retesting After Treatment Helps Identify Reinfection: Treating an STI does not necessarily prevent a person from becoming infected again. CDC recommends that people treated for chlamydia or gonorrhea be retested about three months after treatment because reinfection is common.
• HIV Prevention Is Also Part of STI Prevention: Some STIs can increase the risk of acquiring or transmitting HIV. Combining STI testing and treatment with appropriate HIV prevention strategies can therefore provide broader protection against sexually transmitted infections.

FAQs

1. What is the most common STI?

HPV is generally considered the most common STI. CDC estimates that more than 42 million Americans have a disease-associated HPV infection, with about 13 million new infections each year. Genital herpes is also very common worldwide, with WHO estimating that 846 million people aged 15 to 49 were living with genital herpes in 2020.

2. How many STI cases occur each year?

WHO estimates that more than 1 million curable STIs are acquired every day worldwide. In 2020, there were an estimated 374 million new infections from chlamydia, gonorrhea, syphilis, and trichomoniasis. The total burden is higher when viral infections such as HPV and herpes are included.

3. Are STIs increasing in the United States?

Recent data show a decline, but the longer-term picture remains concerning. Reported chlamydia, gonorrhea, and syphilis cases fell by about 9% between 2023 and 2024. However, the combined number remained 13% higher than a decade earlier, while congenital syphilis cases were nearly 700% higher than a decade ago.

4. What is the most commonly reported STI in the United States?

Chlamydia is the most commonly reported nationally notifiable STI in the U.S. There were approximately 1.52 million reported chlamydia cases in 2024, compared with about 543,000 gonorrhea cases and 190,000 total syphilis cases.

5. Is syphilis still increasing?

It depends on the country and population. In the U.S., total reported syphilis cases fell from 209,249 in 2023 to 190,242 in 2024. However, congenital syphilis increased for the 12th consecutive year. In the EU/EEA, syphilis notification rates more than doubled between 2015 and 2024.

6. Can condoms prevent all STIs?

No, condoms do not prevent all STIs. When used correctly and consistently, they can greatly reduce the risk of infections such as HIV, chlamydia, and gonorrhea. However, they provide less protection against infections such as HPV, genital herpes, and syphilis, which can spread through skin-to-skin contact in areas that a condom does not cover.

Wrapping Up

STI statistics show that sexually transmitted infections will remain an important public health challenge in the coming years. More than 1 million curable STIs are acquired every day worldwide, while infections such as HPV and genital herpes continue to affect hundreds of millions of people. 

Recent declines in some U.S. STI cases are encouraging, but the overall burden remains higher than it was a decade ago, and congenital syphilis continues to be a major concern. Future progress will depend on earlier testing, better access to treatment, vaccination, consistent condom use, and stronger public health surveillance. 

Improving STI data collection will also help identify infections that currently go undiagnosed or unreported. As testing and prevention become more accessible, health systems can detect infections earlier, reduce transmission, and prevent serious complications.