STD Rates in California
CDC surveillance data for California covering chlamydia, gonorrhea, syphilis, and HIV — with 15-year trends, state rankings, and national comparisons.
California ranks 20th out of 50 states for combined STD burden — squarely in the upper half, with a combined rate of 697.6 per 100,000 people. That ranking alone isn't the story, though. What's more telling is the direction things are moving: after years of climbing, California's rates for all three major STDs dropped in 2023. Gonorrhea and syphilis fell the most. Whether that's a turning point or a single-year fluctuation is the open question.
Chlamydia is California's highest-volume disease by far — 191,357 cases in 2023, at a rate of 491.1 per 100,000. That puts the state just above the national median of 471.3, but only barely. The more notable fact is what happened over time: chlamydia rates rose steadily from 280 per 100,000 in 2000, peaked near 600 in 2019, then fell sharply in 2020 — almost certainly a testing artifact from the pandemic — and have been plateauing since. The 0.5% dip in 2023 keeps the trend flat rather than reversing it.
Gonorrhea tells a sharper story. Since 2008, California's gonorrhea rate has risen 169% — from 70.6 to 190.2 per 100,000. That puts the state 25% above the national median of 152.2. The rate peaked at 233.1 in 2021 and has been pulling back since, with a 7.5% drop in 2023. Syphilis followed a similar arc: it climbed from 6 per 100,000 in 2008 to a high of 22.2 in 2021, then fell to 16.3 by 2023 — an 18.9% single-year decline, and now just above the national median of 14.8. Two diseases rising sharply, then retreating in tandem — that's not a coincidence, and it's worth watching.
HIV data runs through 2022. California recorded 4,899 new diagnoses that year, at a rate of 14.8 per 100,000 — nearly back to 2017 levels after a brief drop during the pandemic years. New diagnoses fell to a low of 4,138 in 2020, but that dip almost certainly reflects disrupted testing rather than reduced transmission. If you're in Los Angeles, San Francisco, or San Diego — cities that have historically driven California's HIV and STD numbers — STDTest.com can help you find a testing location nearby.
STD Trends in California
California's chlamydia rate has been essentially flat for three years, hovering just above the national median of 471.3. The plateau follows a long climb — rates nearly doubled between 2000 and 2019 — but the 2023 figure of 491.1 represents a 0.5% decline, the second consecutive year without meaningful growth. The long-run rise of roughly 20% since 2008 is modest compared to gonorrhea and syphilis, suggesting chlamydia trends in California have stabilized even as other diseases continued climbing.
Gonorrhea has been California's fastest-moving STD over the past 15 years. The rate rose 169% from 2008 to its 2021 peak, and even after two years of decline, it sits at 190.2 per 100,000 — 25% above the US median of 152.2. The 7.5% drop in 2023 is real, but it follows a period of such sustained growth that California remains well above where it was a decade ago.
Syphilis in California surged from 6 per 100,000 in 2008 to 22.2 in 2021 — nearly four times the starting rate in 13 years. The recent reversal has been sharper than the other diseases: an 18.9% drop in 2023 brought the rate to 16.3, just above the national median of 14.8. That's a notable shift, but the rate is still nearly three times what it was in 2008.
California's HIV data covers 2017 through 2022. New diagnoses fell from 4,920 in 2017 to a low of 4,138 in 2020, but that drop lines up with pandemic-era testing disruptions rather than a genuine reduction in transmission — the number climbed back to 4,899 by 2022. The overall trend since 2017 is essentially flat, with the state recording a rate of 14.8 per 100,000 in 2022, nearly identical to where it started.
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California vs National Average
Comparing 2023 rates against the U.S. median across all 50 states.
| Infection | California | US Median | Difference |
|---|---|---|---|
| Chlamydia | 491.1 | 471.3 | 4.2% above |
| Gonorrhea | 190.2 | 152.2 | 25% above |
| Syphilis (P&S) | 16.3 | 14.8 | 10.1% above |
What the numbers mean — and what to do about them
Nearly 272,000 Californians were diagnosed with chlamydia, gonorrhea, or syphilis in 2023. That's a combined rate of 697.6 per 100,000 — ninth-largest state population in terms of raw numbers, and a disease burden that puts California in the upper half nationally. The good news, if you want to call it that, is that all three rates fell in 2023. The less comfortable truth is that gonorrhea is still 25% above the national median, and syphilis — despite its sharp recent decline — is nearly three times its 2008 rate.
The trend that matters most clinically is gonorrhea's long rise. A 169% increase since 2008 doesn't happen because people are getting more symptomatic infections — it happens because gonorrhea frequently produces no symptoms at all, especially in women, and infections go undetected without testing. The same applies to chlamydia, which accounts for the majority of California's STD case volume. When rates climb that steadily over that long a period, the gap between diagnosed cases and actual infections tends to grow quietly alongside them.
If you live in California — especially in Los Angeles, San Francisco, or San Diego, where STD and HIV case counts are concentrated — regular testing is one of the few ways to know where you actually stand. California's gonorrhea rate spent more than a decade climbing while most people had no idea. STDTest.com can show you where to get tested today, so you're not one of the cases that goes undetected.
WHO SHOULD GET TESTED
Sexually active adults in California — particularly those in Los Angeles, San Francisco, and San Diego, where STD rates are highest. California's gonorrhea rate is 25% above the national median, and chlamydia remains above average, making routine screening relevant even for people without symptoms. Gay and bisexual men face elevated risk for both gonorrhea and syphilis given California's historical case distribution.
HOW OFTEN
At least once a year if you're sexually active. Given that California's gonorrhea and syphilis rates — even after recent declines — remain above national medians, twice-yearly testing makes sense if you have multiple partners. The post-2021 declines in syphilis and gonorrhea are real, but rates are still well above where they were a decade ago.
WHAT TO EXPECT
Testing is straightforward — typically a urine sample and a blood draw, sometimes a swab depending on the test. Most results come back within a few days. Many clinics in California offer same-day appointments and confidential results. If a test comes back positive, treatment for chlamydia, gonorrhea, and syphilis is available and effective.
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