Sexually Transmitted Infections
Overview of Sexually Transmitted Infections in Allegheny County, 2025
Sexually transmitted infections (STIs) remain a significant public health burden nationwide and in Allegheny County. In 2024, more than 2.2 million cases of chlamydia, gonorrhea and syphilis were reported in the U.S. 1 Between 2023 and 2024, gonorrhea has decreased by 10% while chlamydia has decreased by 8% in the U.S. Primary and secondary syphilis has decreased 22% while congenital syphilis cases are up by 2%. Cases of unknown duration or late syphilis and early latent syphilis are down by 1.5% and 11.3% respectively. Significant reductions in new cases are not only possible but urgently needed to prevent the many negative long-term consequences associated with these infections.
This summary describes reported cases of four STIs (chlamydia, gonorrhea, syphilis and HIV/AIDS) in Allegheny County, focusing primarily on cases reported in 2025. The purpose of this summary is to inform healthcare providers, policymakers, residents and other community partners about the impact of STIs in the county. All reportable STIs have decreased between 2024 and 2025 (Table 1). Overall, the rate of chlamydia and early syphilis in 2024 (year for which the most recent national data is available) was lower in Allegheny County compared to the United States, while the rate of gonorrhea in Allegheny County was higher than the rate of gonorrhea in the United States(Table 2). Visit the ACHD HIV/STI Dashboard to learn more about rates of STIs and basic demographic information of those with various STIs.
Table 1. Overview of Reportable STIs in Allegheny County, 2024 to 2025
| Infection |
2024 |
2025 |
Change from 2024 to 2025 |
| Chlamydia |
5,190 |
4,744 |
-9% |
| Gonorrhea |
2,574 |
1,850 |
-28% |
Early Syphilis*
|
191 |
109 |
-43% |
| HIV** |
78 |
X |
X |
*Early syphilis includes primary, secondary, and early latent syphilis cases.
**2025 data for HIV is not yet available (as of 4/17/2026)
Table 2. Rates per 100,000 of Reportable STIs in Allegheny County, Pennsylvania, United States, 2024
| Infection |
Allegheny County |
Pennsylvania |
United States |
|
Chlamydia
|
421.3
|
X
|
445.7
|
|
Gonorrhea
|
209.0
|
X
|
159.8
|
|
Early Syphilis
|
15.5
|
X
|
26.2
|
|
HIV1
|
7.5
|
7.1
|
X
|
1HIV rates for individuals 15+ years in Allegheny County, and 13+ years in Pennsylvania and United States.
X — Rates are currently unavailable.
HIV/AIDS
In 2024, there were 78 newly diagnosed cases of HIV reported in Allegheny County. These 78 cases represent an 18% increase from the 66 newly diagnosed cases reported in 2023 (Figure 1). Most cases reported in 2024 were among males (74%) and individuals 15-44 years old (85%). Of the 78 cases, 22 cases (28%) were diagnosed with AIDS within 3 months of the initial HIV diagnosis, signifying late diagnosis of HIV. By comparison, 29% of newly diagnosed cases in 2023 were late diagnoses.
Figure 1. Newly diagnosed HIV cases in Allegheny County by sex at birth, 2014 to 2024
Black individuals made up 54% of new HIV diagnoses in 2024 and have made up the majority of new diagnoses in the last 10 years. However, the total number of diagnoses in both Black and white individuals has decreased since 2015. The rate of new HIV diagnoses per 100,000 population was almost 10 times higher in Black individuals compared with white individuals (Figure 2).
Figure 2. Rate of newly diagnosed HIV cases by race, Allegheny County, 2014 to 2024
Men who have sex with men (MSM) continued to account for a majority (51%) of newly diagnosed HIV cases, and heterosexual contact accounted for 21% of cases in 2023 (Figure 3). The risk factor was unknown for 17% of newly diagnosed cases.
Figure 3. Newly diagnosed cases of HIV in Allegheny County by risk factor, 2024
Syphilis
In 2025, there were 109 reported cases of early syphilis (early latent, primary and secondary syphilis). Total early cases of syphilis decreased from 2024 to 2025 by 26%. The rate of early syphilis in Allegheny County is at its lowest in the last decade (Figure 4).
Figure 4. Rate (per 100,000) of newly diagnosed Early Syphilis cases reported in Allegheny County, Pennsylvania and the United States 2016 to 2025
Seventy nine percent of early syphilis cases were among males, an overall rate of 14.3 cases per 100,000 population compared to a rate of 3.7 cases per 100,000 among females (Figure 5). The highest rate was among individuals 35 – 44 years.
Figure 5. Rate of early syphilis cases per 100,000 reported in Allegheny County by sex and age group, 2025
Black individuals represented 42% of early syphilis cases, which is down from 48% in 2024. While white individuals represented 45% of early syphilis cases, the rate of early syphilis per 100,000 population in Black individuals is 5.8 times that of white individuals.
Chlamydia
In 2025, there were 4,744 new cases of chlamydia reported in Allegheny County. The rate of new chlamydia cases was 385.1 cases per 100,000 population, which is an 8.6% decrease from 2024. Despite this decrease chlamydia rates have remained relatively stable since 2016 (Figure 6). Chlamydia affected Black individuals at a rate 12 times that of white individuals (Figure 6).
Figure 6. Rate per 100,000 of chlamydia cases by race reported in Allegheny County, 2016 to 2025
Of all reported cases, 62% were among females. Rate of cases in females has remained consistently higher than the rate of cases in males over the last 10 years. The rates among males and females decreased slightly from levels in 2016, after achieving a peak in 2019. (Figure 7).
Figure 7. Rate per 100,000 of chlamydia cases reported in Allegheny County by sex, 2025
From 2016 to 2025, the rate of new chlamydia cases decreased by 608 cases per 100,000 population among individuals 15 to 24 years old. In that same period, there were slight increases among individuals 35 years and older (Figure 8).
Figure 8. Rate of chlamydia cases per 100,000 reported in Allegheny County by age group, 2016 to 2025
Note: the age group 0-14 years has similarly small rates to the 45+ age group which is why it is difficult to see the overlapping lines.
Gonorrhea
There were 1,850 new cases of gonorrhea reported in Allegheny County in 2025. The rate of new cases of gonorrhea was 150.2 per 100,000 population, representing a 28% decrease from 2024, and is the lowest rate of gonorrhea in the last 10 years (Figure 9). Rate of gonorrhea has remained consistently higher in Black residents compared to White residents. In 2025, the rate of new gonorrhea cases for Black individuals was 9 times that of White individuals (Figure 9).
Figure 9. Rate of gonorrhea cases by race per 100,000 reported in Allegheny County, 2016 to 2025
More cases occurred among males (67%) than among females (33%) in 2025. The rate of new cases among males was 207.2 per 100,000 population, down from a rate of 278.9 cases per 100,000 in 2024 (Figure 10).
Figure 10. Rate of newly diagnosed gonorrhea cases per 100,000 reported in Allegheny County by sex, 2016 to 2025
The highest rate of gonorrhea cases was in individuals 15-24 years (Figure 11). The rate of new cases is at the lowest level in 10 years for individuals 15 to 24 years and 25 to 34 years, however, case rates are higher for individuals 35 years and older, compared to case rates in 2016 for the same age group.
Figure 11. Rate of gonorrhea cases per 100,000 reported in Allegheny County by age group, 2016-2025
Resources
Screening and Treatment
Prevention
- To reduce the risk of HIV and STI transmission use condoms. Free condoms are available through the ACHD Condom Distribution Program.
- Pre-Exposure Prophylaxis (PrEP) is a medication that is taken daily to lower chances of getting HIV. It is designed for individuals who are at high risk for getting HIV. Taking PrEP before you are exposed to HIV can reduce your risk of contracting the disease. Learn more about PrEP here: AIDS Free Pittsburgh PrEP Information.
- If you are an injection drug user, use sterile syringes and works. Learn more about accessing these materials: Prevention Point Pittsburgh Injection Supplies
Trends in HIV/STI Cases
AIDS Free Pittsburgh
AIDS Free Pittsburgh is a collaborative initiative comprised of government agencies, healthcare institutions, and community-based organizations that strive to support and improve the care of people living with HIV/AIDS, as well as communities most at-risk for HIV.
References
- Centers for Disease Control and Prevention. Sexually Transmitted Infections Surveillance 2023. Atlanta: US Department of Health and Human Services; 2025.