STD Rates in New Castle County, Delaware

2023 CDC surveillance data for New Castle County, Delaware — chlamydia, gonorrhea, and syphilis rates with state comparisons.

Data Year: 2023 Source: CDC STI Surveillance Population: 578,611
Combined
814.6
per 100K
2nd / 3
Chlamydia
610.6
per 100K • 3,533 cases
US rate: 490.7
2nd of 3 in Delaware
Higher than 86% of US counties
Gonorrhea
184.1
per 100K • 1,065 cases
US rate: 178.2
1st of 3 in Delaware
Higher than 82% of US counties
Syphilis P&S
19.9
per 100K • 115 cases
US rate: 15.8
1st of 3 in Delaware
Higher than 80% of US counties

New Castle County recorded a combined STD rate of 814.6 per 100,000 residents in 2023, ranking 2nd of 3 counties in Delaware. Reported infections included chlamydia at 610.6 per 100,000 (3,533 cases, 10% above the state rate), gonorrhea at 184.1 per 100,000 (1,065 cases, 21% above the state rate), syphilis at 19.9 per 100,000 (115 cases, 14% above the state rate). Routine testing is the surest way to catch STDs early, since many produce no symptoms. New Castle County has confidential testing locations available.

STD Trends in New Castle County, 2000–2023

Reported cases per 100,000 residents each year, against the Delaware 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
610.6
per 100K in 2023
350.2 in 2000
Peak 645.7 in 2018
Gonorrhea
184.1
per 100K in 2023
236.7 in 2000
Peak 236.7 in 2000
Syphilis (P&S)
19.9
per 100K in 2023
0.4 in 2000
Peak 25.9 in 2022

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

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New Castle County vs Delaware and the US

Infection New Castle County Delaware US vs Delaware vs US Rank in Delaware
Chlamydia 610.63,533 cases 552.7 490.7 10.5% above 24.4% above 2nd of 3
Gonorrhea 184.11,065 cases 151.9 178.2 21.2% above 3.3% above 1st of 3
Syphilis (P&S) 19.9115 cases 17.4 15.8 14.4% above 25.9% above 1st of 3

Rates per 100,000 residents, 2023. Ranks run from the highest rate (1st) among Delaware’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

New Castle County ranks 2nd of 3 Delaware counties for combined STD rate in 2023, at 814.6 per 100,000 residents.
In 2023, chlamydia was the most frequently reported STD in New Castle County, with 3,533 cases at a rate of 610.6 per 100,000 residents.
STDTest.com lists confidential testing locations across New Castle County and Delaware. 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.