Syphilis Rates by State 2023: Where Cases Are Rising Fastest

In 2023 the US primary and secondary (P&S) syphilis rate reached 15.8 per 100,000 CDC AtlasPlus, 2023. Rates vary enormously by state. South Dakota, Washington DC, New Mexico, and Mississippi topped the list at several times the national average, while Idaho and Maine ran lowest. Where you live shapes how often you should be screened for syphilis.

The national surge: how fast and why

Syphilis has climbed for more than a decade, and the pace has accelerated. The country recorded roughly 53,000 primary-and-secondary cases in 2023 CDC STI Surveillance, 2023, the infectious stages that surveillance tracks most closely because they spread the disease. The quieter late and unknown-duration stage rose even faster, jumping from about 14 to nearly 30 per 100,000 between 2020 and 2023. Infections are being caught later and circulating longer.

Several forces drive the surge. Heterosexual transmission has expanded the affected population well beyond the men-who-have-sex-with-men networks where syphilis once concentrated. Methamphetamine and heroin use are tied to delayed care and missed treatment. Inconsistent condom use, multiple partners, and gaps in screening let the bacterium Treponema pallidum move silently, since its first sore is often painless and easy to miss, so people pass it on without knowing. For the broader picture across infections, see our overview of STD rates by state.

Primary & secondary syphilis by state (ranked)

P&S syphilis is the most infectious stage, so its state rate is the cleanest signal of where active transmission is highest. The District of Columbia led the list, followed by a cluster of Southern and Western states. Here are the highest and lowest reporting jurisdictions in the 2023 CDC data.

Note the overlap with gonorrhea: DC, Alaska, Louisiana, and Georgia also report some of the country's highest gonorrhea rates (DC at 853.3, Alaska at 310.9 per 100,000). Both bacteria travel through the same sexual networks, so a high rate of one usually flags a high rate of the other in the same community.

Congenital syphilis: the downstream crisis

The most alarming consequence of rising syphilis in women is congenital syphilis, infection passed from a pregnant person to the baby across the placenta. National cases reached 3,882 in 2023, up from 2,163 in 2020, a roughly 79% jump in three years and the highest level in decades CDC AtlasPlus. This curve mirrors the surge in P&S syphilis among women, which has climbed sharply since 2015 as heterosexual transmission expanded.

The stakes are severe. Untreated syphilis in pregnancy harms the baby in 50 to 80% of cases: stillbirth, premature birth, newborn death, or a live-born infant with congenital infection WHO. Nearly all of this is preventable with a timely blood test and penicillin. The USPSTF urges screening at the first prenatal visit, with a repeat test later in pregnancy in high-prevalence areas USPSTF screening. We dig deeper into the data and the prevention failures behind it in our report on the congenital syphilis crisis.

Who is most affected

Syphilis is not spread evenly across the population. The recognized risk factors include having multiple partners, men who have sex with men, trading sex for money or drugs, methamphetamine or heroin use, and inconsistent condom use. Drug use matters partly because it's linked to delayed care; people present later, after the infection has progressed and spread.

The demographic story has shifted. Syphilis was historically concentrated among men who have sex with men, and that group still carries a high burden. The recent increase in case counts has been driven heavily by heterosexual transmission, which fuels rising infections in women of reproductive age and, downstream, in their newborns. Anyone with syphilis also carries roughly double the risk of acquiring HIV, because genital sores create an easy entry point for the virus.

What a high state rate means for your testing decisions

State-level rates change the math on your personal risk. If you live in DC, Arkansas, Alabama, Louisiana, Arizona, or Alaska, the background prevalence is high enough that periodic syphilis screening is reasonable even when you'd rate your own risk as modest. In a high-prevalence area, the pool of potentially infected partners is larger, so any given exposure carries more weight.

Screening is straightforward. The first-line test is an RPR or VDRL, a simple blood draw with results typically in one to three days; a positive is confirmed with a separate treponemal test StatPearls. There's no swab and no special prep. If you want the full walkthrough of the tests and what the titers mean, read our guide to syphilis testing, and to recognize the warning signs at each phase, see syphilis symptoms by stage.

Syphilis is curable with penicillin at any stage, and early infection clears with fewer doses than late disease. A single benzathine penicillin injection treats early syphilis; three weekly injections cover late or unknown-duration disease. No oral pill dependably substitutes. Catching it early through routine screening is the difference between one shot and a months-long follow-up. You can get tested without symptoms, which is what screening is for.