STD Rates in Illinois
CDC surveillance data for Illinois covering chlamydia, gonorrhea, syphilis, and HIV — with 15-year trends, state rankings, and national comparisons.
Illinois ranks 12th in the country for its combined STD rate — a position that puts it well into the top quarter of states, with a combined rate of 771.6 per 100,000 people. That number is 21% above the US combined median. The state's gonorrhea rate is the part of that picture that doesn't fit neatly into any improving trend narrative: at 202.3 per 100,000, it sits one-third above the national median, and it's been near or above that threshold for several years running.
Chlamydia is Illinois's highest-volume disease by far — nearly 70,000 cases in 2023, translating to a rate of 557.7 per 100,000. That's 18% above the US median of 471.3. The longer view is where the story gets complicated: the rate has climbed 21% since 2008, but the trajectory has flattened recently. After peaking near 639 in 2019, it's been drifting downward, and 2023 marked a 2% drop from 2022. Illinois isn't getting worse on chlamydia right now — but it was never particularly close to the national median to begin with.
Gonorrhea tells a sharper story. Illinois's rate has risen 25.6% since 2008, topping out at 242.4 in 2020 before pulling back. The 2023 rate of 202.3 is down from that peak — and down 3.8% from 2022 — but it still clears the national median of 152.2 by a wide margin. Syphilis, by contrast, is one area where Illinois actually comes in below the US median. At 11.6 per 100,000, it's below the national median of 14.8 — though that number has nearly tripled since 2008, when it sat at 4.3. The rate has been essentially flat for the last two years, which is a different kind of stability than improvement.
HIV diagnoses in Illinois have followed a complicated path since 2017. New cases fell from 1,398 in 2017 to a low of 1,096 in 2020 — a dip almost certainly shaped by pandemic disruptions to testing rather than a real reduction in transmission — then climbed back to 1,294 in 2022. The trend since 2021 is moving in the wrong direction. If you live in Chicago, Aurora, Naperville, or anywhere across Illinois, STDTest.com can help you find a nearby testing location for HIV and all major STDs.
STD Trends in Illinois
Illinois's chlamydia rate has been above the national median for well over a decade, and the gap hasn't closed — it's just stopped widening as quickly. After rising steadily from 460.9 in 2008 to a peak of 639.3 in 2019, the rate has pulled back to 557.7 in 2023, a 2% year-over-year decline. The long-run increase of 21% since 2008 means Illinois entered its current plateau from a high baseline, not a low one.
Illinois's gonorrhea rate has risen 25.6% since 2008 and now sits 33% above the national median of 152.2 — one of the more persistent gaps between a large state and the US middle. The rate peaked at 242.4 in 2020 and has been declining since, falling another 3.8% in 2023, but the pace of that decline is gradual. At 202.3 per 100,000, Illinois remains in well-above-median territory regardless of the downward drift.
Syphilis is the one STD where Illinois actually tracks below the national median — at 11.6 per 100,000 versus a US median of 14.8. But the long-run context matters: the rate was 4.3 in 2008, meaning it has nearly tripled over 15 years even as it stays below average nationally. The rate held flat in 2023 with zero year-over-year change, continuing a plateau that's been in place since roughly 2020.
Illinois HIV data runs through 2022 only, so it doesn't capture the most recent picture. New diagnoses fell from 1,398 in 2017 to 1,096 in 2020, but that drop tracks closely with pandemic-era testing disruptions — not a reliable indicator of reduced transmission. Since 2020, cases have climbed back toward pre-pandemic levels, reaching 1,294 in 2022, a trend that suggests the earlier decline was more about access than incidence.
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Illinois vs National Average
Comparing 2023 rates against the U.S. median across all 50 states.
| Infection | Illinois | US Median | Difference |
|---|---|---|---|
| Chlamydia | 557.7 | 471.3 | 18.3% above |
| Gonorrhea | 202.3 | 152.2 | 32.9% above |
| Syphilis (P&S) | 11.6 | 14.8 | 21.6% below |
STD Rates by County
County-level data from CDC surveillance. Ranked by combined rate per 100,000.
| County | State Rank | Combined | Chlamydia | Gonorrhea | Syphilis |
|---|---|---|---|---|---|
| Jackson County | #1 of 102 | 1526.7 | 1079.8 | 406.6 | 40.3 |
| Peoria County | #2 of 102 | 1309.2 | 875.4 | 415.2 | 18.6 |
| Alexander County | #3 of 102 | 1278.0 | 766.8 | 511.2 | 0.0 |
| Macon County | #4 of 102 | 1262.6 | 778.4 | 430.5 | 53.7 |
| St. Clair County | #5 of 102 | 1184.4 | 815.5 | 347.4 | 21.5 |
| Cook County | #6 of 102 | 1127.1 | 790.0 | 319.7 | 17.4 |
| Pulaski County | #7 of 102 | 1079.2 | 794.1 | 264.7 | 20.4 |
| Vermilion County | #8 of 102 | 1052.3 | 693.6 | 353.1 | 5.6 |
| Champaign County | #9 of 102 | 935.6 | 700.2 | 227.1 | 8.3 |
| Sangamon County | #10 of 102 | 911.1 | 590.7 | 304.4 | 16.0 |
| Coles County | #11 of 102 | 875.0 | 629.6 | 243.2 | 2.2 |
| Winnebago County | #12 of 102 | 843.2 | 673.1 | 152.7 | 17.4 |
| Mclean County | #13 of 102 | 749.8 | 535.1 | 211.8 | 2.9 |
| Rock Island County | #14 of 102 | 747.8 | 542.4 | 191.9 | 13.5 |
| Mcdonough County | #15 of 102 | 711.7 | 529.1 | 175.1 | 7.5 |
| Logan County | #16 of 102 | 648.8 | 482.1 | 163.1 | 3.6 |
| Kankakee County | #17 of 102 | 625.8 | 457.8 | 164.2 | 3.8 |
| Madison County | #18 of 102 | 619.6 | 441.9 | 160.2 | 17.5 |
| Perry County | #19 of 102 | 614.6 | 390.2 | 195.1 | 29.3 |
| Dekalb County | #20 of 102 | 613.3 | 501.6 | 105.7 | 6.0 |
| Williamson County | #21 of 102 | 581.6 | 424.2 | 133.4 | 24.0 |
| Stephenson County | #22 of 102 | 577.7 | 498.8 | 76.6 | 2.3 |
| Cass County | #23 of 102 | 563.6 | 452.5 | 103.2 | 7.9 |
| Adams County | #24 of 102 | 518.3 | 401.9 | 114.8 | 1.6 |
| Morgan County | #25 of 102 | 491.6 | 398.3 | 84.0 | 9.3 |
| Saline County | #26 of 102 | 463.4 | 332.3 | 118.0 | 13.1 |
| Lake County | #27 of 102 | 461.9 | 382.4 | 75.3 | 4.2 |
| Marion County | #28 of 102 | 455.4 | 368.1 | 87.3 | 0.0 |
| Kane County | #29 of 102 | 445.5 | 370.5 | 71.3 | 3.7 |
| Massac County | #30 of 102 | 439.2 | 285.5 | 153.7 | 0.0 |
| Franklin County | #31 of 102 | 438.9 | 309.7 | 110.4 | 18.8 |
| Will County | #32 of 102 | 432.5 | 337.6 | 90.5 | 4.4 |
| Edgar County | #33 of 102 | 428.6 | 330.6 | 98.0 | 0.0 |
| Randolph County | #34 of 102 | 422.6 | 298.5 | 107.3 | 16.8 |
| Knox County | #35 of 102 | 419.3 | 332.6 | 82.6 | 4.1 |
| Tazewell County | #36 of 102 | 411.4 | 310.3 | 95.7 | 5.4 |
| Montgomery County | #37 of 102 | 404.9 | 267.5 | 133.8 | 3.6 |
| Crawford County | #38 of 102 | 404.4 | 338.8 | 65.6 | 0.0 |
| Jefferson County | #39 of 102 | 393.8 | 300.1 | 85.4 | 8.3 |
| Mason County | #40 of 102 | 391.3 | 287.5 | 95.8 | 8.0 |
| Wabash County | #41 of 102 | 383.9 | 246.8 | 137.1 | 0.0 |
| Richland County | #42 of 102 | 381.0 | 271.2 | 90.4 | 19.4 |
| Wayne County | #43 of 102 | 374.4 | 209.4 | 165.0 | 0.0 |
| Scott County | #44 of 102 | 360.9 | 276.0 | 63.7 | 21.2 |
| Fulton County | #45 of 102 | 347.3 | 264.3 | 79.9 | 3.1 |
| Kendall County | #46 of 102 | 345.8 | 282.2 | 59.3 | 4.3 |
| Boone County | #47 of 102 | 342.0 | 300.7 | 33.8 | 7.5 |
| Marshall County | #48 of 102 | 325.2 | 222.5 | 102.7 | 0.0 |
| Dupage County | #49 of 102 | 321.6 | 261.8 | 57.4 | 2.4 |
| Greene County | #50 of 102 | 320.6 | 268.6 | 43.3 | 8.7 |
| Clark County | #51 of 102 | 318.1 | 225.3 | 92.8 | 0.0 |
| Iroquois County | #52 of 102 | 317.7 | 256.4 | 53.6 | 7.7 |
| Whiteside County | #53 of 102 | 313.8 | 256.9 | 45.9 | 11.0 |
| Cumberland County | #54 of 102 | 311.9 | 253.4 | 58.5 | 0.0 |
| Ford County | #55 of 102 | 309.5 | 249.1 | 60.4 | 0.0 |
| Putnam County | #56 of 102 | 305.7 | 269.7 | 36.0 | 0.0 |
| Macoupin County | #57 of 102 | 304.4 | 240.8 | 56.8 | 6.8 |
| Bond County | #58 of 102 | 304.0 | 212.8 | 85.1 | 6.1 |
| Union County | #59 of 102 | 294.0 | 228.0 | 54.0 | 12.0 |
| Lasalle County | #60 of 102 | 291.8 | 232.7 | 55.4 | 3.7 |
| Jo Daviess County | #61 of 102 | 280.3 | 206.8 | 73.5 | 0.0 |
| De Witt County | #62 of 102 | 279.9 | 201.8 | 78.1 | 0.0 |
| Fayette County | #63 of 102 | 278.9 | 203.2 | 66.2 | 9.5 |
| Lawrence County | #64 of 102 | 276.8 | 229.5 | 47.3 | 0.0 |
| Lee County | #65 of 102 | 264.4 | 205.0 | 47.5 | 11.9 |
| Effingham County | #66 of 102 | 259.2 | 209.7 | 49.5 | 0.0 |
| Christian County | #67 of 102 | 258.8 | 180.6 | 78.2 | 0.0 |
| Moultrie County | #68 of 102 | 258.0 | 209.2 | 48.8 | 0.0 |
| Livingston County | #69 of 102 | 254.8 | 223.7 | 31.1 | 0.0 |
| Washington County | #70 of 102 | 251.2 | 206.9 | 44.3 | 0.0 |
| Pike County | #71 of 102 | 251.0 | 209.2 | 41.8 | 0.0 |
| Hancock County | #72 of 102 | 250.2 | 215.3 | 34.9 | 0.0 |
| Clay County | #73 of 102 | 246.2 | 200.0 | 46.2 | 0.0 |
| Woodford County | #74 of 102 | 245.5 | 193.3 | 49.6 | 2.6 |
| Piatt County | #75 of 102 | 245.3 | 209.4 | 35.9 | 0.0 |
| Ogle County | #76 of 102 | 238.0 | 204.8 | 27.3 | 5.9 |
| Mchenry County | #77 of 102 | 233.3 | 203.0 | 26.5 | 3.8 |
| Clinton County | #78 of 102 | 228.3 | 182.1 | 46.2 | 0.0 |
| Jersey County | #79 of 102 | 227.5 | 184.9 | 37.9 | 4.7 |
| Hardin County | #80 of 102 | 224.2 | 112.1 | 84.1 | 28.0 |
| Henry County | #81 of 102 | 222.9 | 187.8 | 33.0 | 2.1 |
| Schuyler County | #82 of 102 | 222.8 | 148.5 | 74.3 | 0.0 |
| Warren County | #83 of 102 | 216.3 | 185.4 | 30.9 | 0.0 |
| Bureau County | #84 of 102 | 201.7 | 171.1 | 30.6 | 0.0 |
| Grundy County | #85 of 102 | 201.6 | 179.2 | 22.4 | 0.0 |
| White County | #86 of 102 | 201.5 | 149.2 | 44.8 | 7.5 |
| Mercer County | #87 of 102 | 200.2 | 148.5 | 51.7 | 0.0 |
| Douglas County | #88 of 102 | 198.7 | 188.5 | 10.2 | 0.0 |
| Shelby County | #89 of 102 | 194.5 | 170.2 | 19.4 | 4.9 |
| Gallatin County | #90 of 102 | 192.7 | 149.9 | 42.8 | 0.0 |
| Edwards County | #91 of 102 | 184.3 | 134.0 | 33.5 | 16.8 |
| Johnson County | #92 of 102 | 180.1 | 172.6 | 7.5 | 0.0 |
| Jasper County | #93 of 102 | 174.9 | 98.4 | 65.6 | 10.9 |
| Monroe County | #94 of 102 | 168.8 | 114.4 | 54.4 | 0.0 |
| Pope County | #95 of 102 | 161.9 | 161.9 | 0.0 | 0.0 |
| Carroll County | #96 of 102 | 154.5 | 109.5 | 38.6 | 6.4 |
| Menard County | #97 of 102 | 150.6 | 125.5 | 25.1 | 0.0 |
| Henderson County | #98 of 102 | 147.8 | 131.4 | 16.4 | 0.0 |
| Stark County | #99 of 102 | 134.2 | 57.5 | 57.5 | 19.2 |
| Hamilton County | #100 of 102 | 113.7 | 101.1 | 0.0 | 12.6 |
| Calhoun County | #101 of 102 | 69.5 | 69.5 | 0.0 | 0.0 |
| Brown County | #102 of 102 | 31.8 | 15.9 | 15.9 | 0.0 |
What the numbers mean — and what to do about them
Nearly 97,000 Illinois residents were diagnosed with chlamydia, gonorrhea, or syphilis in 2023. At a combined rate of 771.6 per 100,000, Illinois isn't an outlier — it's a large, dense state with the STD numbers that tend to come with that — but it does sit 21% above the US combined median and ranks 12th nationally. That's not a marginal gap. For a state of 12.5 million people, the case volume translates into a disease burden that touches communities across the state, not just its largest city.
The trend most worth watching in Illinois is gonorrhea. It peaked at 242.4 per 100,000 in 2020 and has been declining since, but it remains one-third above the national median — and gonorrhea is particularly prone to asymptomatic spread. Most people who have it don't know. The same is true for chlamydia, where Illinois's rate of 557.7 has been elevated for years. When infections go undetected, they keep moving. Routine testing is the mechanism that interrupts that — not symptoms, because symptoms often don't come.
If you're in Chicago, Aurora, Naperville, or anywhere else in Illinois, testing is straightforward and widely available. You don't need a doctor's referral. Most results come back within a few days. Illinois's gonorrhea rate has been above the national median for the better part of a decade — not because people aren't concerned, but because the infections don't announce themselves. STDTest.com can show you exactly where to get tested today.
WHO SHOULD GET TESTED
Sexually active adults in Illinois are testing into a state with above-median rates for both chlamydia and gonorrhea. Anyone with new or multiple partners, or who hasn't tested in the past year, fits the profile where routine screening matters most. Illinois's gonorrhea rate is 33% above the national median — that risk doesn't distribute itself evenly, but it doesn't stay confined to any single group either.
HOW OFTEN
Annual testing is a reasonable baseline for sexually active adults given Illinois's sustained above-median rates. If you have multiple partners or a new partner, every three to six months is more appropriate. Illinois's chlamydia and gonorrhea rates have been elevated for over a decade — frequency matters more than any single test.
WHAT TO EXPECT
STD testing in Illinois is fast and low-friction. Depending on what you're testing for, it typically involves a urine sample, a swab, or a blood draw — sometimes a combination. Most results are returned within a few days. Clinics across Chicago, Aurora, and Naperville offer confidential testing, and many don't require insurance.
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