Why Syphilis Is Surging Again

How much has syphilis actually risen?

Syphilis has risen sharply over the past generation. Cases climbed year after year for more than two decades, and in 2023 the United States recorded more than 209,000 syphilis infections across all stages 1Ref 1Centers for Disease Control and Prevention (2025).National Overview of STIs in 2023.The 2023 U.S. syphilis and combined-STI case counts (over 209,000 syphilis and over 2.4 million chlamydia/gonorrhea/syphilis cases), the first decline in primary and secondary syphilis in over two decades, and that nearly half of reported STIs are in people aged 15-24.. That was one piece of a larger surge: over 2.4 million chlamydia, gonorrhea, and syphilis cases combined in a single year, with nearly half of all reported STIs in people aged 15 to 24 1Ref 1Centers for Disease Control and Prevention (2025).National Overview of STIs in 2023.The 2023 U.S. syphilis and combined-STI case counts (over 209,000 syphilis and over 2.4 million chlamydia/gonorrhea/syphilis cases), the first decline in primary and secondary syphilis in over two decades, and that nearly half of reported STIs are in people aged 15-24.. Within that combined total, chlamydia remained the single largest infection, at over 1.6 million reported cases, while gonorrhea actually declined — so the picture is not a uniform surge but a patchwork, with syphilis and its youngest patients among the sharpest edges 1Ref 1Centers for Disease Control and Prevention (2025).National Overview of STIs in 2023.The 2023 U.S. syphilis and combined-STI case counts (over 209,000 syphilis and over 2.4 million chlamydia/gonorrhea/syphilis cases), the first decline in primary and secondary syphilis in over two decades, and that nearly half of reported STIs are in people aged 15-24..

There is one genuinely hopeful line in that data. Primary and secondary syphilis — the earliest, most infectious stages — fell for the first time in over twenty years 1Ref 1Centers for Disease Control and Prevention (2025).National Overview of STIs in 2023.The 2023 U.S. syphilis and combined-STI case counts (over 209,000 syphilis and over 2.4 million chlamydia/gonorrhea/syphilis cases), the first decline in primary and secondary syphilis in over two decades, and that nearly half of reported STIs are in people aged 15-24.. It is a single year, and a fragile one, so it reads better as an early turn than a settled trend. The long arc is still a steep climb up from the near-elimination of syphilis a generation ago.

The U.S. recorded more than 209,000 syphilis cases in 2023 1Ref 1Centers for Disease Control and Prevention (2025).National Overview of STIs in 2023.The 2023 U.S. syphilis and combined-STI case counts (over 209,000 syphilis and over 2.4 million chlamydia/gonorrhea/syphilis cases), the first decline in primary and secondary syphilis in over two decades, and that nearly half of reported STIs are in people aged 15-24..

Why syphilis is so easy to miss

Syphilis earns its old nickname, the great imitator, because most of its stages are quiet or easily mistaken for something else. The first sign is often a single painless sore at the spot where the infection entered — and because it does not hurt and heals on its own, it is easy to ignore 2Ref 2Centers for Disease Control and Prevention (2024).About Syphilis.The staged natural history of syphilis (painless primary sore/chancre, secondary rash, latent silent stage) and that untreated infection can progress to neurosyphilis, ocular syphilis, or otosyphilis at any stage.. That is the whole trap: the body seems to recover while the infection moves inward.

A chancre is the firm, usually painless ulcer of primary syphilis. Weeks later comes the secondary syphilis stage: a rash that can spread across the body, including the palms and soles, along with fever or swollen glands. It, too, fades without treatment 2Ref 2Centers for Disease Control and Prevention (2024).About Syphilis.The staged natural history of syphilis (painless primary sore/chancre, secondary rash, latent silent stage) and that untreated infection can progress to neurosyphilis, ocular syphilis, or otosyphilis at any stage.. After that the infection enters latent syphilis — the silent stage, with no symptoms at all, sometimes for years. This syphilis symptom mimicry is exactly what fools both patients and clinicians, and it is why the genital sore differential between a syphilis chancre and a herpes blister is worth taking seriously rather than guessing at. What looks like healing is the infection going underground, and left untreated it can eventually reach the brain, eyes, or ears — neurosyphilis, ocular syphilis, or otosyphilis — at any stage 2Ref 2Centers for Disease Control and Prevention (2024).About Syphilis.The staged natural history of syphilis (painless primary sore/chancre, secondary rash, latent silent stage) and that untreated infection can progress to neurosyphilis, ocular syphilis, or otosyphilis at any stage.. Because its rash and flu-like signs copy so many other illnesses, syphilis is often mistaken for a viral rash, an allergic reaction, or nothing worth a second look — which is exactly how it moves from person to person while everyone involved believes it is something else 2Ref 2Centers for Disease Control and Prevention (2024).About Syphilis.The staged natural history of syphilis (painless primary sore/chancre, secondary rash, latent silent stage) and that untreated infection can progress to neurosyphilis, ocular syphilis, or otosyphilis at any stage..

Is the 2023 decline actually good news?

It is genuinely encouraging, and it is also narrow. The drop applies to primary and secondary syphilis — the two earliest, most contagious stages — and it is the first such decline in more than twenty years 1Ref 1Centers for Disease Control and Prevention (2025).National Overview of STIs in 2023.The 2023 U.S. syphilis and combined-STI case counts (over 209,000 syphilis and over 2.4 million chlamydia/gonorrhea/syphilis cases), the first decline in primary and secondary syphilis in over two decades, and that nearly half of reported STIs are in people aged 15-24.. That matters, because those are the stages that drive onward transmission, so a dip there can ripple forward.

But it is one year set against a two-decade climb, and it does not yet touch the parts of the epidemic that worry clinicians most. Total syphilis across all stages stayed above 209,000 cases, and the newborn toll of congenital syphilis has not turned the same corner 1Ref 1Centers for Disease Control and Prevention (2025).National Overview of STIs in 2023.The 2023 U.S. syphilis and combined-STI case counts (over 209,000 syphilis and over 2.4 million chlamydia/gonorrhea/syphilis cases), the first decline in primary and secondary syphilis in over two decades, and that nearly half of reported STIs are in people aged 15-24.. The honest reading is cautious optimism: a possible inflection, not a resolved problem. Whether the line keeps bending depends on exactly the things this page is about — finding the people who have no symptoms, and treating what gets found.

What makes syphilis spread so efficiently?

Several features let syphilis move quietly between partners. The long silent stretch is the biggest: during the latent phase there is nothing to notice, so people pass the infection on without knowing they carry it 2Ref 2Centers for Disease Control and Prevention (2024).About Syphilis.The staged natural history of syphilis (painless primary sore/chancre, secondary rash, latent silent stage) and that untreated infection can progress to neurosyphilis, ocular syphilis, or otosyphilis at any stage.. Timing compounds this — the early sore is painless and short-lived, so the window when someone might seek care often closes before they walk into a clinic.

Protection is also imperfect. Consistent, correct condom use is highly effective against STIs that spread through genital fluids, but it offers only partial protection against syphilis, which passes through direct skin-to-skin contact with a sore that a condom may not cover 3Ref 3Centers for Disease Control and Prevention (2024).Condom Use: An Overview.That consistent, correct condom use is highly effective against STIs spread by genital fluids but provides only partial protection against syphilis, which spreads by skin-to-skin contact.. Layer on the fact that nearly half of reported STIs are among people under 25 — a group not always screened on schedule 1Ref 1Centers for Disease Control and Prevention (2025).National Overview of STIs in 2023.The 2023 U.S. syphilis and combined-STI case counts (over 209,000 syphilis and over 2.4 million chlamydia/gonorrhea/syphilis cases), the first decline in primary and secondary syphilis in over two decades, and that nearly half of reported STIs are in people aged 15-24. — and the result is an infection well suited to spreading faster than the systems built to catch it. None of this makes syphilis unstoppable — each of these features is answered by testing people who feel well and treating whatever turns up — but together they explain why case counts climbed for two decades before they finally budged.

Why congenital syphilis is the most alarming part of the rise

The steepest human cost of the resurgence is congenital syphilis — the infection passing from a pregnant person to the fetus. Untreated, it can cause miscarriage, stillbirth, death shortly after birth, and severe, lifelong damage to a baby who survives 4Ref 4Centers for Disease Control and Prevention (2024).About Congenital Syphilis.That syphilis can pass to a fetus during pregnancy, causing miscarriage, stillbirth, infant death, and severe outcomes, and that penicillin given during pregnancy is the only treatment proven to prevent congenital syphilis.. As adult cases climbed, congenital cases climbed alongside them, for a simple reason: a syphilis infection in pregnancy that is never found is never treated.

The prevention here is unusually definitive. Penicillin given during pregnancy is the only treatment proven to prevent congenital syphilis 4Ref 4Centers for Disease Control and Prevention (2024).About Congenital Syphilis.That syphilis can pass to a fetus during pregnancy, causing miscarriage, stillbirth, infant death, and severe outcomes, and that penicillin given during pregnancy is the only treatment proven to prevent congenital syphilis.. That is why the timing of prenatal screening carries so much weight — a test early in pregnancy, and again later for those at higher risk, is what stands between a treatable infection and a preventable tragedy. Anyone thinking through congenital syphilis is looking at the part of this epidemic that public-health officials describe as the most urgent to reverse.

Who should be screened for syphilis?

Because syphilis hides, screening — testing people who have no symptoms — is the main way it gets caught. The US Preventive Services Task Force gives its strongest rating, a Grade A recommendation, to screening asymptomatic, nonpregnant adolescents and adults who are at increased risk of infection 5Ref 5US Preventive Services Task Force (2022).Syphilis Infection in Nonpregnant Adolescents and Adults: Screening.The 2022 USPSTF Grade A recommendation to screen for syphilis in asymptomatic, nonpregnant adolescents and adults who are at increased risk of infection.. A Grade A means the benefit is well established, and clinicians generally fold it into routine sexual-health care rather than waiting for a symptom to appear.

Pregnancy is handled separately and more broadly, since the stakes there are congenital syphilis 4Ref 4Centers for Disease Control and Prevention (2024).About Congenital Syphilis.That syphilis can pass to a fetus during pregnancy, causing miscarriage, stillbirth, infant death, and severe outcomes, and that penicillin given during pregnancy is the only treatment proven to prevent congenital syphilis.. For everyone else, what counts as "increased risk" is a conversation worth having plainly with a clinician rather than self-diagnosing — it turns on sexual history, partners, and local rates, not on how anyone feels. The reassuring part is that the test itself is a simple blood draw, and a positive result at an early stage points toward a straightforward cure.

What actually lowers the risk

Two things drive the numbers down: catching infections and preventing them. Syphilis remains fully treatable — penicillin is the standard, and treatment early in the disease is far simpler than treating its later complications 4Ref 4Centers for Disease Control and Prevention (2024).About Congenital Syphilis.That syphilis can pass to a fetus during pregnancy, causing miscarriage, stillbirth, infant death, and severe outcomes, and that penicillin given during pregnancy is the only treatment proven to prevent congenital syphilis.. Finding cases early through screening is therefore prevention in its own right, because a treated infection cannot be passed on.

On the prevention side, condoms lower but do not erase risk, given the skin-to-skin route 3Ref 3Centers for Disease Control and Prevention (2024).Condom Use: An Overview.That consistent, correct condom use is highly effective against STIs spread by genital fluids but provides only partial protection against syphilis, which spreads by skin-to-skin contact.. A newer tool is doxy-PEP: the 2024 CDC guideline recommends counseling and offering a single dose of the antibiotic doxycycline, taken within 72 hours after sex, to gay and bisexual men and transgender women who have had a bacterial STI — syphilis, chlamydia, or gonorrhea — in the previous year, paired with STI testing every three to six months 6Ref 6Bachmann LH, Barbee LA, Chan P, et al. (Centers for Disease Control and Prevention) (2024).CDC Clinical Guidelines on the Use of Doxycycline Postexposure Prophylaxis for Bacterial Sexually Transmitted Infection Prevention, United States, 2024.The 2024 CDC recommendation to counsel and offer doxy-PEP (a single doxycycline dose within 72 hours after sex) to gay and bisexual men and transgender women who had a bacterial STI in the prior 12 months, with STI testing every 3-6 months.. It is one of the few prevention tools designed directly in response to the rise in bacterial STIs, and it is not for everyone; who actually benefits is a specific clinical conversation.

Syphilis is curable, and screening people who feel fine is the main lever for bending the curve back down.

How is syphilis diagnosed and treated?

Syphilis is diagnosed with a blood test — and usually two of them, read together. A first, inexpensive screening test flags a possible infection, and a second, more specific test confirms it, because the screening test can sometimes react for reasons other than syphilis 7Ref 7Workowski KA, Bachmann LH, Chan PA, et al. (Centers for Disease Control and Prevention) (2021).Sexually Transmitted Infections Treatment Guidelines, 2021.That syphilis is diagnosed with sequential blood tests (a screening test confirmed by a more specific test) and that penicillin given by injection is the recommended treatment, with the regimen varying by stage of infection.. In particular situations — an active sore, or concern about the brain, eyes, or ears — a clinician may test fluid from the sore or the spinal fluid directly. The practical point is that no single result diagnoses syphilis; it is a pattern of tests interpreted together, which is why diagnosis belongs with a clinician rather than a home guess.

Treatment is well established and highly effective. Penicillin, given by injection, is the standard treatment at every stage, and the CDC's treatment guidelines lay out how the regimen changes with how long the infection has been present — a short course for early disease, and more for late or neurological infection 7Ref 7Workowski KA, Bachmann LH, Chan PA, et al. (Centers for Disease Control and Prevention) (2021).Sexually Transmitted Infections Treatment Guidelines, 2021.That syphilis is diagnosed with sequential blood tests (a screening test confirmed by a more specific test) and that penicillin given by injection is the recommended treatment, with the regimen varying by stage of infection.. A treated infection stops progressing and can no longer be passed to anyone else, so catching it early does double duty as both cure and prevention. People with a penicillin allergy are managed individually by their clinician rather than left untreated.

Caught early, syphilis is straightforwardly curable — the danger comes from the years it can hide, not from the treatment.

What to do if you think you were exposed

The first move is testing, not watching for symptoms — because with syphilis there often are none to watch for, which is also true of the asymptomatic STI majority more broadly 2Ref 2Centers for Disease Control and Prevention (2024).About Syphilis.The staged natural history of syphilis (painless primary sore/chancre, secondary rash, latent silent stage) and that untreated infection can progress to neurosyphilis, ocular syphilis, or otosyphilis at any stage.. A blood test is what confirms or rules out syphilis, and it is offered through primary care, sexual-health clinics, and many community programs. Anyone who is pregnant, or whose partner has tested positive, is a reason to be seen promptly rather than to wait and see.

If a recent sore, a rash across the palms and soles, or a partner's diagnosis is what prompted the question, that is a reason to test now and to say plainly what happened, so the right tests are ordered. Treatment early is simple. The cost of waiting is that syphilis keeps moving through its stages toward the brain, eyes, and ears 2Ref 2Centers for Disease Control and Prevention (2024).About Syphilis.The staged natural history of syphilis (painless primary sore/chancre, secondary rash, latent silent stage) and that untreated infection can progress to neurosyphilis, ocular syphilis, or otosyphilis at any stage.. With this infection, testing is nearly the whole game — there is no version of it where waiting helps, because the sooner syphilis is found, the simpler it is to cure and the fewer people it reaches.