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 2023 in suburban Cook County, there were:
- 10,806 chlamydia cases (472.5 per 100,000 population)
- 3,061 gonorrhea cases (133.8 per 100,000 population)
- 157 PSS cases (6.9 per 100,000 population)
- 12 congenital syphilis cases
In suburban Cook County, chlamydia cases decreased slightly (1.2%) from 2022 to 2023, but the rates were still high. The chlamydia rate in non-Hispanic Black/African American persons was 11 times higher than the rate in non-Hispanic Whites. The rate in Hispanic/Latinx persons was 4.4 times higher than the rate in non-Hispanic Whites. The rate in non-Hispanic Asians was about 33% lower than the rate in non-Hispanic Whites (see Figure 3).
In terms of gonorrhea, there was a 5.6% decrease in reported cases from 2022 to 2023 in suburban Cook County. This is the second year since 2021 that 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.
In suburban Cook County, disparities by race/ethnicity were even greater for gonorrhea than for chlamydia. The rate in non-Hispanic Black/African American persons was 18 times higher than the rate in non-Hispanic Whites. The rate in Hispanic/Latino persons was 3.5 times higher than the rate in non-Hispanic Whites. The rate in non-Hispanic Asians was about 4.7% lower than the rate in non-Hispanic Whites (see Figure 7). Chlamydia and gonorrhea rates were highest in those aged 20-24 years of age (Figures 4 and 8).
The number of PSS cases in suburban Cook County fell slightly from 159 in 2022 to 157 in 2023. The number of PSS cases in 2023 was the lowest since 2015. Although PSS rates in men and women were stable from 2022 to 2023, the number of congenital syphilis cases rose slightly from 10 in 2022 to 12 in 2023.
Trends in Chlamydia and Gonorrhea
Figure 1. Trends in Chlamydia and Gonorrhea Cases, Suburban Cook County, 2014-2023
- Chlamydia case counts fell 1.2% from 2022 to 2023. Although declines were modest, this is the second year since 2021 that chlamydia case counts decreased.
- Gonorrhea case counts fell 5.6% from 2022 to 2023. Like chlamydia, this is the second year since 2021 that gonorrhea cases declined.
- The number of gonorrhea cases reported in 2023 (n=3,061) is the lowest since 2017 (n=2,935).
Figure 2. Trends in Chlamydia Rates by Select Public Health Jurisdictions
- In suburban Cook County, there was a modest 1.2% reduction in the chlamydia rate from 2022 to 2023.
- Chlamydia rates in suburban Cook County are the lowest of the selected jurisdictions from 2019-2023.
- At the time this report was revised, there were no chlamydia data available for Chicago for 2022 or 2023.
Figure 3. Chlamydia Rates by Race/Ethnicity, Suburban Cook County, 2023
- The rate in non-Hispanic Black/African American persons was about 11 times higher than the rate in non-Hispanic Whites.
- The rate in Hispanic/Latino persons was 4.4 times higher than the rate in non-Hispanic Whites.
- The rate in non-Hispanic Asians was 33% lower than the rate in non-Hispanic Whites.
Figure 4. Chlamydia Rates by Sex and Age Group, Suburban Cook County, 2023
- Chlamydial infections are concentrated in younger people, especially those aged 15-24 years of age.
- 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 go to the doctor more often than men and get screened more often.
Figure 5. Trends in Chlamydia Rates by Public Health District, Suburban Cook County, 2019-2023
- Chlamydia rates vary by Public Health District, with rates highest in the South District.