STD Rates in Colorado
CDC surveillance data for Colorado covering chlamydia, gonorrhea, syphilis, and HIV — with 15-year trends, state rankings, and national comparisons.
Colorado sits in the bottom half of states for STD burden, ranking 31st out of 50 on combined rates in 2023. That sounds reassuring — until you look at where the numbers have been going. Two of the three major STDs fell year-over-year, which is genuinely unusual nationally. But the longer arc tells a more complicated story, particularly for syphilis, which has done something almost no other disease trajectory in this dataset does: it's been climbing without interruption for over a decade.
Chlamydia is Colorado's highest-volume STD, as it is nearly everywhere. The state recorded 25,571 cases in 2023, at a rate of 435.1 per 100,000 — comfortably below the national median of 471.3. That gap wasn't always there. Colorado's chlamydia rate crossed 500 in 2018 and 2019 before pulling back during the pandemic years, and it's continued to ease since. The 2023 figure is down 4.6% from 2022, and down meaningfully from the 2019 peak of 517.8. Whether that's a sustained plateau or a temporary dip is the real question.
Gonorrhea fell sharply in 2023 — 14.4% in a single year, from 150.4 to 128.7 per 100,000. That puts Colorado back below the national median of 152.2, after briefly crossing above it in the late 2010s. The long-run picture is still striking: gonorrhea rates nearly tripled between 2014 and 2021, from 59.3 to 182.3. The recent decline is real, but it's recovering from a significant run-up. Syphilis, meanwhile, hasn't shown any sign of easing. At 16.0 per 100,000, it's now above the national median of 14.8 — a rate that was essentially zero (0.3) back in 2000. The long-run increase since 2008 is 515%. That number is not a rounding error.
HIV data through 2022 shows Colorado averaging roughly 400 new diagnoses per year, with a rate of 8.9 per 100,000 in the most recent year available. The 2020 dip to 324 cases almost certainly reflects pandemic-related disruptions to testing access, not an actual reduction in transmission. Rates have since recovered toward pre-pandemic levels. If you're in Denver, Colorado Springs, or Aurora, STDTest.com can help you find a testing location near you — because the only way any of these numbers improve is if more people know their status.
STD Trends in Colorado
Colorado's chlamydia rate has been gradually pulling away from its 2019 peak of 517.8 per 100,000, and at 435.1 in 2023 it now sits about 8% below the national median of 471.3. The decline isn't new — rates have been softening since 2020 — but the pace has been slow, and the long-run rise from 389.2 in 2008 is still a 12% net increase over 15 years. The plateau, not a spike, is the story here.
Gonorrhea in Colorado has pulled back significantly from its 2021 peak of 182.3 per 100,000, dropping to 128.7 in 2023 — a 14.4% single-year decline that pushed the rate below the national median of 152.2. But context matters: the rate was just 46.1 in 2011, meaning it nearly quadrupled before this recent retreat. A two-year decline after a decade-long surge is worth watching, not celebrating.
Syphilis is the outlier in Colorado's data. At 16.0 per 100,000 in 2023, it has crossed above the national median of 14.8 — and it has risen in nearly every year since 2009, when the rate was 2.1. The 515% long-run increase since 2008 is the sharpest trajectory in Colorado's STD dataset by a wide margin, and 2023's 1.9% year-over-year uptick shows no sign of reversal.
Colorado's HIV data covers 2017 through 2022, and over that period new diagnoses have hovered in a fairly narrow band — generally between 397 and 460 per year, with a rate around 8 to 9.5 per 100,000. The 2020 figure of 324 cases is the clear exception, and is almost certainly a product of reduced testing access during the pandemic rather than a true drop in transmission. By 2022, diagnoses had climbed back to 444 — close to the pre-pandemic baseline.
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Colorado vs National Average
Comparing 2023 rates against the U.S. median across all 50 states.
| Infection | Colorado | US Median | Difference |
|---|---|---|---|
| Chlamydia | 435.1 | 471.3 | 7.7% below |
| Gonorrhea | 128.7 | 152.2 | 15.4% below |
| Syphilis (P&S) | 16 | 14.8 | 8.1% above |
STD Rates by County
County-level data from CDC surveillance. Ranked by combined rate per 100,000.
| County | State Rank | Combined | Chlamydia | Gonorrhea | Syphilis |
|---|---|---|---|---|---|
| San Juan County | #1 of 61 | 1496.3 | 1371.6 | 124.7 | 0.0 |
| Denver County | #2 of 61 | 1232.2 | 851.0 | 338.8 | 42.4 |
| Adams County | #3 of 61 | 774.2 | 588.2 | 168.2 | 17.8 |
| Pueblo County | #4 of 61 | 772.7 | 523.0 | 208.4 | 41.3 |
| Arapahoe County | #5 of 61 | 709.1 | 528.2 | 159.7 | 21.2 |
| El Paso County | #6 of 61 | 585.7 | 452.4 | 118.8 | 14.5 |
| Alamosa County | #7 of 61 | 522.4 | 438.3 | 72.1 | 12.0 |
| Morgan County | #8 of 61 | 511.4 | 436.9 | 67.7 | 6.8 |
| Prowers County | #9 of 61 | 485.0 | 425.5 | 25.5 | 34.0 |
| Otero County | #10 of 61 | 479.7 | 341.9 | 126.8 | 11.0 |
| Lake County | #11 of 61 | 475.3 | 393.8 | 81.5 | 0.0 |
| Rio Grande County | #12 of 61 | 464.8 | 357.5 | 62.6 | 44.7 |
| Garfield County | #13 of 61 | 462.5 | 413.0 | 41.5 | 8.0 |
| Conejos County | #14 of 61 | 452.1 | 292.5 | 79.8 | 79.8 |
| Mesa County | #15 of 61 | 450.9 | 350.1 | 81.4 | 19.4 |
| Bent County | #16 of 61 | 422.4 | 334.4 | 70.4 | 17.6 |
| Moffat County | #17 of 61 | 420.2 | 360.2 | 60.0 | 0.0 |
| Summit County | #17 of 61 | 420.2 | 364.4 | 52.5 | 3.3 |
| Weld County | #19 of 61 | 415.9 | 343.3 | 66.5 | 6.1 |
| Jefferson County | #20 of 61 | 411.7 | 299.8 | 103.4 | 8.5 |
| Boulder County | #21 of 61 | 405.8 | 326.2 | 74.4 | 5.2 |
| La Plata County | #22 of 61 | 397.1 | 304.9 | 76.2 | 16.0 |
| Eagle County | #23 of 61 | 369.6 | 312.6 | 51.5 | 5.5 |
| Broomfield County | #24 of 61 | 363.0 | 274.5 | 84.6 | 3.9 |
| Saguache County | #25 of 61 | 358.8 | 328.9 | 29.9 | 0.0 |
| San Miguel County | #26 of 61 | 355.9 | 355.9 | 0.0 | 0.0 |
| Las Animas County | #27 of 61 | 355.5 | 306.7 | 20.9 | 27.9 |
| Montezuma County | #28 of 61 | 339.2 | 241.2 | 90.5 | 7.5 |
| Larimer County | #29 of 61 | 329.5 | 274.8 | 50.4 | 4.3 |
| Huerfano County | #30 of 61 | 311.8 | 269.3 | 28.3 | 14.2 |
| Costilla County | #31 of 61 | 303.2 | 248.1 | 55.1 | 0.0 |
| Kit Carson County | #32 of 61 | 300.3 | 214.5 | 71.5 | 14.3 |
| Routt County | #33 of 61 | 295.2 | 259.3 | 31.9 | 4.0 |
| Pitkin County | #34 of 61 | 294.4 | 246.4 | 24.0 | 24.0 |
| Gunnison County | #35 of 61 | 282.9 | 254.0 | 28.9 | 0.0 |
| Logan County | #36 of 61 | 281.2 | 223.1 | 53.3 | 4.8 |
| Fremont County | #37 of 61 | 254.3 | 230.5 | 23.8 | 0.0 |
| Montrose County | #38 of 61 | 253.6 | 217.4 | 29.4 | 6.8 |
| Gilpin County | #39 of 61 | 253.2 | 219.4 | 16.9 | 16.9 |
| Washington County | #40 of 61 | 247.2 | 226.6 | 20.6 | 0.0 |
| Cheyenne County | #41 of 61 | 231.6 | 115.8 | 57.9 | 57.9 |
| Douglas County | #42 of 61 | 230.9 | 186.8 | 39.9 | 4.2 |
| Crowley County | #43 of 61 | 230.6 | 177.4 | 53.2 | 0.0 |
| Jackson County | #44 of 61 | 229.2 | 229.2 | 0.0 | 0.0 |
| Phillips County | #45 of 61 | 201.1 | 201.1 | 0.0 | 0.0 |
| Delta County | #46 of 61 | 189.1 | 157.5 | 28.4 | 3.2 |
| Yuma County | #47 of 61 | 182.5 | 172.4 | 10.1 | 0.0 |
| Elbert County | #48 of 61 | 180.6 | 149.3 | 27.8 | 3.5 |
| Clear Creek County | #49 of 61 | 174.9 | 164.0 | 10.9 | 0.0 |
| Baca County | #50 of 61 | 149.5 | 149.5 | 0.0 | 0.0 |
| Kiowa County | #51 of 61 | 144.5 | 144.5 | 0.0 | 0.0 |
| Teller County | #52 of 61 | 134.1 | 97.5 | 24.4 | 12.2 |
| Chaffee County | #53 of 61 | 131.0 | 101.9 | 9.7 | 19.4 |
| Park County | #54 of 61 | 115.9 | 88.3 | 27.6 | 0.0 |
| Grand County | #55 of 61 | 112.9 | 94.1 | 18.8 | 0.0 |
| Mineral County | #56 of 61 | 105.9 | 105.9 | 0.0 | 0.0 |
| Archuleta County | #57 of 61 | 105.7 | 91.6 | 14.1 | 0.0 |
| Rio Blanco County | #58 of 61 | 60.9 | 60.9 | 0.0 | 0.0 |
| Ouray County | #59 of 61 | 58.0 | 58.0 | 0.0 | 0.0 |
| Lincoln County | #60 of 61 | 54.7 | 18.2 | 36.5 | 0.0 |
| Custer County | #61 of 61 | 54.2 | 36.1 | 18.1 | 0.0 |
What the numbers mean — and what to do about them
Colorado's combined STD rate of 579.8 per 100,000 translates to more than 34,000 diagnosed cases of chlamydia, gonorrhea, and syphilis in a single year — in a state of just under 6 million people. Ranking 31st nationally means Colorado is neither an outlier nor a model. It sits in the middle of the pack on volume, but the internal trends are moving in different directions depending on which disease you're looking at.
The most clinically significant trend is syphilis. A 515% increase over 15 years is not a statistical artifact — it reflects real, ongoing transmission in a disease that is entirely curable if caught early and potentially serious if not. Syphilis is also frequently asymptomatic in early stages, which means most people carrying it have no idea. The same is true for the majority of chlamydia and gonorrhea infections. Colorado's gonorrhea rate fell 14.4% in 2023, which is encouraging on a spreadsheet — but the rate is still 70% higher than it was in 2008, and a two-year decline doesn't erase a decade of accumulation in a population where many infections go undetected and untreated.
If you live in Denver, Colorado Springs, or Aurora, the practical implication is simple: routine testing is the only way to know your status, because symptoms usually aren't. Colorado's syphilis rate crossed the national median in 2023 for the first time — a quiet shift that won't make the news but matters if you're sexually active and haven't been tested recently. STDTest.com can show you exactly where to get tested in your city today, with no appointment barriers and results that give you something symptoms never will: certainty.
WHO SHOULD GET TESTED
Any sexually active adult in Colorado should consider routine STD screening, but particularly those in the Denver metro and Front Range corridor where case volume is highest. Given that Colorado's syphilis rate now exceeds the national median and gonorrhea remains well above its pre-2015 baseline, people with new or multiple partners face meaningfully elevated risk — regardless of symptoms.
HOW OFTEN
Once a year is a reasonable floor for most sexually active adults in Colorado. Given the sustained rise in syphilis — up nearly every year since 2009 — and gonorrhea rates that are still 70% above where they were 15 years ago, anyone with multiple partners or inconsistent protection should consider testing every three to six months. Frequency should match actual risk, not assumptions about it.
WHAT TO EXPECT
Standard STD testing in Colorado typically involves a urine sample or swab, sometimes a blood draw for syphilis and HIV. Most visits take under 30 minutes. Results usually come back within a few days. Testing is confidential, and many locations in Denver, Colorado Springs, and Aurora offer sliding-scale fees or accept insurance. If something comes back positive, treatment for chlamydia, gonorrhea, and syphilis is straightforward with antibiotics.
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