STD Rates in Merrimack County, New Hampshire

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

Data Year: 2023 Source: CDC STI Surveillance Population: 157,135
Combined
218.9
per 100K
3rd / 10
Chlamydia
180.1
per 100K • 283 cases
US rate: 490.7
3rd of 10 in New Hampshire
Higher than 23% of US counties
Gonorrhea
33.1
per 100K • 52 cases
US rate: 178.2
3rd of 10 in New Hampshire
Higher than 28% of US counties
Syphilis P&S
5.7
per 100K • 9 cases
Based on 9 cases — interpret with care
US rate: 15.8

Merrimack County reported a combined STD rate of 218.9 per 100,000 residents in 2023, placing it 3rd of 10 New Hampshire counties — in the upper half of the state. Reported infections included chlamydia at 180.1 per 100,000 (283 cases, 8% below the state rate), gonorrhea at 33.1 per 100,000 (52 cases, 21% below the state rate), syphilis at 5.7 per 100,000 (9 cases, too few for a reliable comparison). Confidential STD testing is available throughout Merrimack County — knowing your status is the only way to catch infections that often show no symptoms.

STD Trends in Merrimack County, 2000–2023

Reported cases per 100,000 residents each year, against the New Hampshire 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
180.1
per 100K in 2023
91.4 in 2000
Peak 316.4 in 2017
Gonorrhea
33.1
per 100K in 2023
9.5 in 2000
Peak 38.7 in 2017
Syphilis (P&S)
5.7
per 100K in 2023
0.7 in 2000
Peak 7.1 in 2021

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

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Merrimack County vs New Hampshire and the US

Infection Merrimack County New Hampshire US vs New Hampshire vs US Rank in New Hampshire
Chlamydia 180.1283 cases 196.6 490.7 8.4% below 63.3% below 3rd of 10
Gonorrhea 33.152 cases 41.9 178.2 21% below 81.4% below 3rd of 10
Syphilis (P&S) 5.79 cases 3.9 15.8 Too few cases Too few cases

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

Merrimack County ranks 3rd of 10 New Hampshire counties for combined STD rate in 2023, at 218.9 per 100,000 residents.
In 2023, chlamydia was the most frequently reported STD in Merrimack County, with 283 cases at a rate of 180.1 per 100,000 residents.
STDTest.com lists confidential testing locations across Merrimack County and New Hampshire. 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.