Sexually Transmitted Infections Surveillance Report

2024-2025

Abbreviations, Acronyms & Definitions

Asian: Refers to non-Hispanic Asian persons.

Black/AA: Refers to non-Hispanic Black/African American persons.

CCDPH: Cook County Department of Public Health. Jurisdiction includes all areas in Cook County, Illinois excluding Chicago, Evanston, Oak Park, Skokie, and Stickney Township.

CDC: Centers for Disease Control and Prevention.

CS: Congenital Syphilis, when a mother infected with syphilis passes it to her baby.

CT: Chlamydia trachomatis, the bacterium that causes chlamydia.

GC: Neisseria gonorrhoeae, the bacterium that causes gonorrhea.

Hispanic/Latino: Refers to Hispanic or Latino persons.

PSS, P&S Syphilis: Primary or secondary syphilis; highly infectious stages of syphilis.

STI: Sexually Transmitted Infection. Generally, this refers to chlamydia (Chlamydia trachomatis), gonorrhea (Neisseria gonorrhoeae) or syphilis (Treponema pallidum) infection.

White: Refers to non-Hispanic White persons.

Executive Summary

In 2025 in suburban Cook County, there were:

• 8,972 chlamydia cases (390.3 per 100,000 population)
• 2,530 gonorrhea cases (110.1 per 100,000 population)
• 107 PSS cases (4.7 per 100,000 population)
• 13 congenital syphilis cases

In 2024 in suburban Cook County, there were:

• 9,684 chlamydia cases (421.7 per 100,000 population)
• 2,949 gonorrhea cases (128.4 per 100,000 population)
• 92 PSS cases (4 per 100,000 population)
• 9 congenital syphilis cases

In suburban Cook County, the number of reported chlamydia cases decreased (10.9%) from 2023 to 2024, then decreased further (7.4%) from 2024 to 2025. While rates of chlamydia were still high, sustained decreases in rates have been observed since 2023. Amidst this decrease in cases, disparities in the burden among different racial and ethnic groups persist throughout suburban Cook County, with non-Hispanic Black/African American persons and Hispanic/Latino persons experiencing disproportionate burden of STI when compared to non-Hispanic White persons. The chlamydia rate in non-Hispanic Black/African American persons was nearly 10 times higher than the rate in non-Hispanic Whites. The rate in Hispanic/Latino persons was 3.2 times higher than the rate in non-Hispanic Whites. The rate in non-Hispanic Asians was about 2 times lower than the rate in non-Hispanic Whites (see Figure 3).

Similarly, there was a 3.8% decrease in reported gonorrhea cases from 2023 to 2024, then a further decrease (14.2%) from 2024 to 2025 in suburban Cook County. This continues a persistent trend of decreasing incidence of reported gonorrhea cases declined. It is not clear whether this is simply variation in reporting, or whether this is the beginning of a sustained decrease in transmission. While there may be a range of factors influencing the trends observed for chlamydia and gonorrhea, it is possible that new prevention methods like DoxyPEP may be contributing. Learn more about DoxyPEP here.

While declines in the number of reported gonorrhea cases is encouraging, racial and ethnic disparities persist for gonorrhea. The rate in non-Hispanic Black/African American persons was over 14 times higher than the rate in non-Hispanic Whites. The rate in Hispanic/Latino persons was 3 times higher than the rate in non-Hispanic Whites. The rate in non-Hispanic Asians was about have that observed among non-Hispanic Whites (see Figure 7). Chlamydia and gonorrhea rates were highest in those aged 20-24 years of age (Figure 4 and Figure 8).

Syphilis continues to be problematic for suburban Cook County, with much of our focus being on the most infectious primary and secondary stages of syphilis (PSS) and congenital syphilis. The number of PSS cases in suburban Cook County fell by nearly 37.9% from 2023 (157 cases) to 2025 (107 cases). Disparities in PSS by racial or ethnic group are even more apparent than those seen for chlamydia and gonorrhea, with the 2025 rate being nearly 16 times higher among non-Hispanic Black/African Americans and 6 times higher among Hispanic/Latinos when compared to non-Hispanic Whites. Although PSS rates trend higher among men than women, the number of congenital syphilis cases remain high in suburban Cook County when compared to counts prior to 2020.

 

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Trends in Chlamydia and Gonorrhea

Figure 1. Trends in Chlamydia and Gonorrhea Cases, Suburban Cook County, 2016-2025

Figure 1

 

• Chlamydia case counts fell 7.4% from 2024 to 2025.
• Gonorrhea case counts fell 14.2% from 2024 to 2025.

 

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Figure 2. Trends in Chlamydia Rate by Select Public Health Jurisdictions

Figure 2

*Both CDC and IDPH migrated data reporting platforms in 2024 and, as a result, 2024 US rates are provisional and data for state and local jurisdictions are delayed.

 

• Chlamydia rates in the CCDPH jurisdiction are the lowest of the selected jurisdictions for all years in which data was avilable for comparison.

 

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Figure 3. Chlamydia Rates by Race/Ethnicity, Suburban Cook County, 2025

Figure 3

 

• The rate in non-Hispanic Black/African American persons was about 10 times higher than the rate in non-Hispanic Whites.
• The rate in Hispanic/Latino persons was 3.2 times higher than the rate in non-Hispanic Whites.
• The rate in non-Hispanic Asians was 44% lower than the rate in non-Hispanic Whites.

 

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Figure 4. Chlamydia Rates by Sex and Age Group, Suburban Cook County, 2025

Figure 4

 

• Chlamydia infections are concentrated in younger people, especially those aged 15-24 years.
• Because symptoms are not common in persons infected with chlamydia, many do not seek care.
• We believe rates are higher in women partially because they have more opportunities for routine screening.

 

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Figure 5. Trends in Chlamydia Rates by Public Health Region, Suburban Cook County, 2021-2025

Figure 5

 

• Chlamydia rates vary by Public Health Region, with rates highest in the South Region.

 

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NoteAttention Providers!

Please click here for a fillable PDF of the Illinois Morbidity Report form for STIs.

Please fax completed morbidity report forms to (708)836-5450.

You may receive a fax or call from CCDPH if certain information on a reported case is missing, like race/ethnicity and/or treatment. It is important to provide this information as soon as possible. Staff may also reach out to ask for additional information such as symptoms, reason for visit, history of syphilis (including past labs), and possibly other questions (i.e. HIV status and pregnancy).

If you have any questions, please contact our Syndemics Program Manager at (708) 836-8617.

 

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Map 1. Chlamydia Rates by Municipality (three-year averages, 2023-2025) per 100,000 Population

 

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Figure 6. Trends in Gonorrhea Rates by Select Public Health Jurisdictions, 2019-2023

Figure 6

*Both CDC and IDPH migrated data reporting platforms in 2024 and, as a result, 2024 US rates are provisional and data for state and local jurisdictions are delayed.

 

• In the CCDPH jurisdiction, there was a 14.3% reduction in the gonorrhea rate from 2024 to 2025.
• Since 2021, the gonorrhea rate in the CCDPH jurisdiction declined 48.1%.

 

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Figure 7. Gonorrhea Rates by Race/Ethnicity, Suburban Cook County, 2025

Figure 7

 

• The rate in non-Hispanic Black/African American persons was about 14.4 times higher than the rate in non-Hispanic Whites.
• The rate in Hispanic/Latino persons was 3 times higher than the rate in non-Hispanic Whites.
• The rate in non-Hispanic Asians was 39% lower than the rate in non-Hispanic Whites.

 

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Figure 8. Gonorrhea Rates by Sex and Age Group, Suburban Cook County, 2025

Figure 8

 

• Gonorrhea rates are highest in both males and females aged 20-24 years.
• Gonorrhea rates are higher in men over 24 years of age compared to women, but all rates decrease in older age groups.

 

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Figure 9. Trends in Gonorrhea Rates by Public Health Region, Suburban Cook County, 2021-2025

Figure 9

 

• Although gonorrhea rates were highest in the South Region, rates declined 44% 2021 to 2025.
• Rates in the West, Southwest and North Regions have been relatively stable from 2021-2025.

 

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Map 2. Gonorrhea Rates by Municipality (three-year averages, 2023-2025) per 100,000 Population

 

NoteAttention Providers!

Are you providing Expedited Partner Therapy to your patients, also known as EPT? Why not?!! EPT is legal in Illinois and highly encouraged! Click here for more information on EPT.

 

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Trends in Primary and Secondary Syphilis (PSS) & Congenital Syphilis

 

Figure 10. Trends in Primary and Secondary Syphilis (PSS) Rates, Suburban Cook County, 2016-2025

Figure 10

 

• Primary and secondary syphilis (PSS) cases increased from 2024 (n=92) to 2025 (n=107).

 

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Figure 11. Trends in PSS Rates by Select Public Health Jurisdictions, 2019-2023

Figure 11

*Both CDC and IDPH migrated data reporting platforms in 2024 and, as a result, 2024 US rates are provisional and data for state and local jurisdictions are delayed.

 

• In the CCDPH jurisdiction, there was a 20.5% increase in the PSS rate from 2024 to 2025.
• PSS rates in the CCDPH jurisdiction are the lowest of the selected jurisdictions from 2021-2025.

 

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Figure 12. Comparison of PSS Rates by Sex and Year of Report, Suburban Cook County, 2023-2025

Figure 12

 

• Reported syphilis rates are consistently higher among males.

 

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Figure 13. PSS Rates by Race/Ethnicity, Suburban Cook County, 2025

Figure 13

 

• The rate in non-Hispanic Black/African American persons was 16.1 times higher than the rate in non-Hispanic Whites.
• The rate in Hispanic/Latino persons was 6.4 times higher than the rate in non-Hispanic Whites.
• No primary and secondary syphilis cases were reported among non-Hispanic Asian residents in 2025.

 

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Figure 14. Percent of Reported PSS Cases by Age Group, Suburban Cook County, 2025

Figure 14

 

• Most PSS cases (53.9%) are reported among people aged 25-39 years, with the largest proportion aged 25-29, 35-39 years (20.8%).

 

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Figure 15. Counts of Congenital Syphilis Cases, Suburban Cook County, 2016-2025

Figure 15

*To protect confidentiality, years with 1-4 cases have been set to n=4 and are shown in light pink.

 

• Thirteen (13) congenital syphilis cases were reported in 2025.

 

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Figure 16. Trends in PSS by Public Health Region, Suburban Cook County, 2019-2023

Figure 16

 

• PSS rates increased for 3 of the public health regions from 2024 to 2025.

 

NoteContinued Shortage of Bicillin L-A

Bicillin L-A® (Benzathine Penicillin G) continues to be in short supply nationally. Healthcare providers should keep track of their current stock and save this medication for pregnant patients with syphilis and newborns with congenital syphilis. Benzathine Penicillin G is the only recommended treatment for these patients, and alternative treatments are available for other groups. The FDA is temporarily allowing importation of Lentocilin©, an equivalent injectable medication, to help address the shortage. See the CDC’s full recommendations for guidance on alternative treatments, accessing Bicillin L-A®, and syphilis management.

 

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Map 3. PSS Rates by Municipality (three-year averages, 2021-2023) per 100,000 Population

NoteTechnical Notes & Limitations

Cook County Department of Public Health Jurisdiction

The jurisdiction of the Cook County Department of Public Health excludes Chicago, Evanston, Oak Park, Skokie and Stickney Township, each of which has its own state-certified local health department. In this document, we use the terms “CCDPH Jurisdiction” and “Suburban Cook County” interchangeably. We have also intentionally omitted municipalities or portions with 0 population or with so few residents that calculating rates is impractical.

Data Methodology

Healthcare providers and laboratories within suburban Cook County are required by law to report positive cases of chlamydia, gonorrhea, and syphilis to the Cook County Department of Public Health within 7 days of diagnosis. The case reports are entered into a secure database hosted by the Illinois Department of Public Health, providing the basis for the information presented in this report.

Rates were calculated using annualized intercensal estimates for population from the US Decennial Census.

Limitations

This report includes all reported cases of chlamydia, gonorrhea, and syphilis but does not represent the entire population of persons infected. This is because not all infected persons have been tested or reported. Additionally, persons with asymptomatic STIs, such as chlamydia, may be underrepresented in surveillance reports because they may not seek care, may remain undiagnosed, and, consequently, are unreported.

In addition to these limitations, it is important to consider that variations in reported cases may represent true increases or decreases; however, these variations may also be a result of improved surveillance due to increased awareness or educational campaigns, more (or less) complete reporting, or similar phenomena that can affect reporting and surveillance.

Data Lags

CCDPH works to release complete and accurate STI data as quickly as possible after data are finalized for CDC submission. This means surveillance data may not be available for all comparison jurisdictions (Chicago, Illinois, and the U.S.) at the time of this report’s publication. Whenever possible, our reports will be revised and re-published when data for these jurisdictions is made available.

Hover over figures to highlight individual data points.

Copyright Information

All materials contained in this report are in the public domain and may be used and reprinted without special permission; citation as to source, however, is appreciated.

Suggested Citation

Cook County Department of Public Health. 2025 Annual STI Surveillance Report, Forest Park, IL 2026