STD Rates in Contra Costa County, California

2023 CDC surveillance data for Contra Costa County, California — chlamydia, gonorrhea, and syphilis rates with state comparisons.

Data Year: 2023 Source: CDC STI Surveillance Population: 1,155,015
Combined
568.8
per 100K
18th / 58
Chlamydia
427.7
per 100K • 4,940 cases
US rate: 490.7
19th of 58 in California
Higher than 72% of US counties
Gonorrhea
127.9
per 100K • 1,477 cases
US rate: 178.2
15th of 58 in California
Higher than 72% of US counties
Syphilis P&S
13.2
per 100K • 153 cases
US rate: 15.8
29th of 58 in California
Higher than 69% of US counties

Contra Costa County reported a combined STD rate of 568.8 per 100,000 residents in 2023, placing it 18th of 58 California counties — in the upper half of the state. Reported infections included chlamydia at 427.7 per 100,000 (4,940 cases, 13% below the state rate), gonorrhea at 127.9 per 100,000 (1,477 cases, 33% below the state rate), syphilis at 13.2 per 100,000 (153 cases, 19% below the state rate). Confidential STD testing is available throughout Contra Costa County — knowing your status is the only way to catch infections that often show no symptoms.

STD Trends in Contra Costa County, 2000–2023

Reported cases per 100,000 residents each year, against the California rate (dashed). In a county this size a handful of cases moves the rate a long way, so read the shape rather than any single year.

Chlamydia
427.7
per 100K in 2023
0.0 in 2000
Peak 537.9 in 2018
Gonorrhea
127.9
per 100K in 2023
0.0 in 2000
Peak 191.3 in 2019
Syphilis (P&S)
13.2
per 100K in 2023
0.1 in 2000
Peak 16.7 in 2021

Source: CDC NCHHSTP AtlasPlus county surveillance, 2000–2023.

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Contra Costa County vs California and the US

Infection Contra Costa County California US vs California vs US Rank in California
Chlamydia 427.74,940 cases 491.1 490.7 12.9% below 12.8% below 19th of 58
Gonorrhea 127.91,477 cases 190.2 178.2 32.8% below 28.2% below 15th of 58
Syphilis (P&S) 13.2153 cases 16.3 15.8 19% below 16.5% below 29th of 58

Rates per 100,000 residents, 2023. Ranks run from the highest rate (1st) among California’s counties. The US rate is all 50 states combined. Comparisons are left out where fewer than 20 cases were reported, because a rate built on so few cases can swing widely from one year to the next.

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FAQs

Contra Costa County ranks 18th of 58 California counties for combined STD rate in 2023, at 568.8 per 100,000 residents.
In 2023, chlamydia was the most frequently reported STD in Contra Costa County, with 4,940 cases at a rate of 427.7 per 100,000 residents.
STDTest.com lists confidential testing locations across Contra Costa County and California. Many offer same-day appointments with results in 1–3 days.
Data sourced from the CDC's annual STI Surveillance Report. Rates are per 100,000 population and reflect reported cases only — actual prevalence is likely higher due to undiagnosed infections. While we strive for accuracy, STDTest.com makes no representations or warranties regarding the completeness or accuracy of this data and is not responsible for any errors or omissions. This page is for informational purposes only and does not constitute medical advice.