Published: August 2025 | Last updated: May 2026
Syphilis was the public-health story almost no one was telling during the COVID years. While the pandemic dominated every headline, an old and curable infection that had been quietly declining for half a century was climbing back, fast. By 2022 the United States was reporting more new syphilis diagnoses than at any point since the 1950s, and the steepest line on the chart belonged to congenital syphilis: babies born with an infection their birthing parent never knew they carried.
This piece walks through what actually happened, why pandemic conditions let a sexually transmitted infection spread under the radar, and what the data looks like now that we are several years past the peak. It is written for readers who want the real picture, not reassurance theater, and who want practical answers about where testing fits in for themselves and the people they care about.
Why Syphilis Returned, Louder Than Before
Syphilis is one of the oldest documented sexually transmitted infections, and by the early 2000s public-health agencies in the United States were close to declaring it controlled. In 2000 the country recorded fewer than 6,000 cases of primary and secondary syphilis, the lowest count since reporting began. Then a slow, persistent climb started. By 2017 cases were already double the early-2000s low, driven by gaps in screening, shrinking public-health budgets, and changes in dating and sexual networks.
The pandemic did not start the surge. It accelerated one that was already in motion. When clinics closed or shifted to COVID triage in 2020, the people most likely to be screened for an STI, often as part of routine sexual-health visits or prenatal care, simply stopped coming in. The infections did not stop. They just stopped being counted, and untreated cases kept transmitting.
According to CDC's 2020 STD Surveillance Report, primary and secondary syphilis cases rose 7% from 2019 to 2020 even as overall STI reporting dropped during the first pandemic year. The real underlying increase was almost certainly larger than the reported number, because reported counts depend on people getting tested in the first place. By 2022 the U.S. counted over 207,000 syphilis cases of all stages, the highest annual total in more than 70 years.
What COVID Broke in Sexual-Health Care
Sexual-health care in the U.S. has always run on a thin margin. A network of public-health clinics, school-based programs, and community testing sites carries most of the load for low-cost screening, especially in lower-income and rural communities. When the pandemic hit, that network bent, and in some places it broke.
In the first months of 2020, CDC surveillance data showed STI case counts dropping sharply across most categories even as syphilis kept rising, a signal that screening capacity had collapsed faster than transmission. Public-health staff were reassigned to COVID case investigation and contact tracing. Mobile testing units stopped running. School-based clinics closed entirely. For people whose only realistic access to screening was a Title X clinic or a county health department, that meant no test for months.
Telehealth picked up part of the slack, but only part. Routine sexual-health screening usually requires a sample (blood for syphilis antibody tests, urine or swabs for chlamydia and gonorrhea), and that requires either an in-person visit or a mail-in collection kit. The infrastructure for mail-in sample collection existed in 2020, but it was niche and not widely advertised. Most people did not know it was an option.
The result was a year-long testing gap during a period when transmission did not slow down. Cases accumulated quietly. Many of them only surfaced later, after partners had been exposed and, in some cases, infections had progressed to the secondary or early latent stage.
Reported syphilis counts depend on people walking into a testing site. When in-person visits collapsed in 2020, the 7% rise CDC documented was happening on a denominator of far fewer tests run. The infections that went uncounted that year showed up in later surveillance as secondary, latent, and congenital cases, which is part of why 2021 and 2022 reported numbers kept climbing.
What Syphilis Does in Your Body, Stage by Stage
Syphilis is caused by the bacterium Treponema pallidum, and it moves through the body in distinct stages. Each stage looks different, and the visible signs are easy to miss. That is part of why the infection spreads so effectively when testing is hard to access.
The primary stage typically starts about three weeks after exposure, when a small ulcer called a chancre appears at the site where the bacteria entered the body: genitals, anus, lips, mouth, or sometimes inside the vagina or rectum where it cannot be seen. The chancre is typically firm, round, and painless. Per the CDC's About Syphilis page, the sore usually lasts 3 to 6 weeks and heals on its own whether or not the person receives treatment, which is why so many people miss it entirely.
The secondary stage follows weeks to months later and is the body's systemic response. Common signs include a non-itchy rash, often on the palms or soles, along with fever, sore throat, swollen lymph nodes, patchy hair loss, and broad weight loss or fatigue (the NHS syphilis page has detailed stage descriptions). These symptoms also resolve without treatment, and many people interpret them as a virus or stress. The bacteria is highly transmissible during both the primary and secondary stages.
The latent stage is the quiet middle. There are no outward symptoms, but the bacteria persists. Early latent syphilis (within 12 months of infection) is still considered transmissible; late latent typically is not, but it can damage organs silently for years. The tertiary stage, which can develop a decade or more after untreated infection, affects the heart, blood vessels, brain, nerves, and other organs. Damage at this stage is often permanent even when the infection itself is eventually cleared.
Primary and secondary: highly infectious through direct contact with chancres, mucous patches, or the secondary rash. Early latent (within 12 months of infection): still considered transmissible to sexual partners. Late latent: typically not transmissible through sex, but can still pass from a pregnant person to the fetus and continues to damage organs silently. Tertiary: not contagious, but the cardiovascular and neurological damage at this stage is often irreversible.
Congenital Syphilis: The Most Heartbreaking Cost
Congenital syphilis happens when a pregnant person passes the infection to the fetus, usually across the placenta. It is fully preventable with prenatal screening and a single course of penicillin, and it is one of the most reliable indicators of how well a country's sexual-health system is functioning. The U.S. number has been moving in the wrong direction for almost a decade.
According to the CDC's About Congenital Syphilis page, cases have more than tripled in recent years, with nearly 4,000 cases reported in 2024, the highest annual count since 1994. CDC's 2023 MMWR Vital Signs review of 2022 cases found that 88% of congenital syphilis cases were attributable to missed prevention opportunities: no testing during pregnancy, no prenatal care, inadequate treatment after a positive test, or late seroconversion that was not caught by retesting.
The consequences for newborns are severe. Stillbirth and early infant death are the most extreme outcomes, but surviving babies can develop bone deformities, severe anemia, jaundice, hearing loss, vision damage, neurological injury, and delayed developmental milestones. Treatment with intravenous penicillin can clear the infection but cannot fully reverse damage that occurred before birth. Prevention through screening is the only reliable strategy.
Treatment: Early Is One Shot, Late Is Years of Care
One of the genuinely encouraging facts about syphilis is that the treatment has not changed much since the 1940s, and it still works. Benzathine penicillin G remains the first-line therapy, and it is highly effective when the infection is caught in its early stages.
Per CDC's STI Treatment Guidelines for primary and secondary syphilis, the recommended regimen is benzathine penicillin G 2.4 million units IM in a single dose. That is one injection, one visit. Most people are non-infectious within 24 to 48 hours after treatment and considered cured after follow-up bloodwork at 6 and 12 months confirms a falling antibody titer.
Late latent and tertiary syphilis are treated with three doses of benzathine penicillin G given one week apart. Neurosyphilis (involvement of the central nervous system) requires intravenous aqueous penicillin for 10 to 14 days, usually in a hospital or infusion clinic. People with severe penicillin allergy may be desensitized so they can still receive penicillin, because no oral antibiotic has been shown to work as reliably for syphilis in pregnancy or in late-stage disease.
If the test is done early, treatment is a single shot. If the test is delayed, the infection may still be curable, but months or years of stealth damage may have already happened.
Who Should Test, and How Often
The simple, slightly oversimplified rule: if you are sexually active and not in a long-term mutually-tested monogamous relationship, you should be screened for syphilis at least once a year. CDC's screening recommendations are more granular, and they have tightened since 2022.
For most sexually active adults under 25, annual screening for chlamydia and gonorrhea is the baseline, and syphilis screening is recommended for anyone with risk factors. For men who have sex with men, CDC recommends syphilis testing at least annually, and every 3 to 6 months for people with multiple partners or any partner whose status is unknown. For people living with HIV, syphilis screening is recommended at every routine HIV care visit.
Pregnancy carries its own protocol, and it has been updated. CDC now recommends syphilis testing at the first prenatal visit for everyone, with retesting at 28 weeks and at delivery for people who live in counties with high syphilis rates or who have other risk factors. The reason is direct: catching seroconversion during pregnancy is the only way to prevent congenital syphilis, and infection can happen at any point in pregnancy.
If you have had a recent partner with a positive STI test, if you have noticed a sore or rash that came and went, or if it has been more than a year since your last test, the default answer is to test. Cost should not be a barrier; most state health departments offer free or low-cost screening, and at-home rapid tests are an option for people who want results without an office visit.
Clinic, Mail-In, or At-Home: Honest Trade-Offs
There are three real ways to test for syphilis in 2026, and each one has a fit. The right choice depends on what you need and how fast you need it.
Clinic-based testing is the gold standard. A provider draws blood, the lab runs a treponemal antibody test (typically EIA or CIA) followed by a non-treponemal confirmation (RPR or VDRL), and the results come back as a quantitative titer that can be tracked over time to confirm treatment success. Sensitivity and specificity for the laboratory algorithm are very high, and the results are immediately usable for treatment decisions and partner notification.
Mail-in testing is a hybrid. You collect a sample at home (usually a dried blood spot or a fingerstick blood collection card) and ship it to a partner laboratory that runs the same kind of treponemal and non-treponemal algorithm a clinic would. Results take a few days but use lab-grade chemistry. This is a good option for people who want lab-grade accuracy without an in-person visit, but it is not instant.
At-home rapid testing uses lateral-flow technology, the same chemistry as a home pregnancy test or a rapid COVID test. A drop of fingerstick blood is applied to a cassette, and a line indicates the presence (or absence) of antibodies to T. pallidum. Results appear in about 15 minutes. The strength of rapid tests is speed, privacy, and access; the limitation is that they screen rather than confirm. A reactive (positive) rapid test should always be followed by a clinic-administered confirmation and titer before starting treatment, because the rapid test cannot quantify how active the infection is.
All three approaches have a place. For ongoing routine screening, clinic visits or annual mail-in tests are ideal. For a faster check after a possible exposure, or for people in places where a clinic is far away, an at-home rapid test bridges the gap.
Why “I Don’t Have Symptoms” Isn’t a Safe Bet
The most common reason people skip syphilis screening is that they feel fine. With most infections, feeling fine is reasonable evidence that nothing is wrong. With syphilis, it is not. The infection is built, biologically speaking, to be quiet.
The primary chancre is small, often painless, and frequently inside the vagina, the anus, or the back of the throat where it cannot be seen. People who notice it at all often dismiss it as a friction sore or an ingrown hair. Within a few weeks it heals on its own, and the visible reminder is gone, but the bacteria has already moved into the bloodstream.
The secondary stage’s rash on the palms and soles is one of the most recognizable signs of syphilis in dermatology, but it does not look alarming. It is usually flat, non-itchy, and brownish-red. People who see a clinician for it are often told it might be a viral rash, an allergic reaction, or psoriasis, and unless syphilis is specifically tested for, the diagnosis can be missed for months.
The latent stage is where the asymmetry becomes most dangerous. There are no visible signs. The person feels healthy. They may continue having sex, and in the first year after infection they may still be transmitting the bacteria. The only way to know is a blood test.
Where We Stand in 2025-2026
The most recent surveillance data shows the first signs of stabilization. CDC's provisional 2024 STI Surveillance Report, released in September 2025, recorded that primary and secondary syphilis cases dropped 22% over two years, marking the second consecutive year-over-year decline after more than a decade of increases. That is the good news.
The less good news is that congenital syphilis cases were still rising into 2024, with nearly 4,000 reported cases (up about 2% from 2023). The reason for the lag is mechanical: congenital cases reflect prenatal screening from roughly nine months earlier, so the curve will not bend until upstream screening fully catches up. Most state public-health departments have made congenital syphilis prevention a priority budget line, and many have expanded same-day treatment access in maternity care.
At the federal level, regulators have expanded acceptance of at-home diagnostic testing across several STI categories, and state Medicaid programs in some jurisdictions have started covering home test kits. Telehealth-prescribed syphilis treatment, while still developing, is a real option in most states.
Per CDC's syphilis and surveillance guidance, the infection is preventable, treatable, and curable, and the most reliable tools to interrupt transmission remain unchanged: routine screening, prompt treatment, and partner notification. The 2024 provisional decline in adult primary and secondary cases is being treated as encouraging but provisional, not as evidence that the broader surge is over.
Frequently asked questions
- Why did syphilis cases rise during the COVID years?
- Clinics closed or shifted to COVID care, public-health staff were reassigned, and routine sexual-health screening volume dropped sharply during 2020. Infections did not stop; they just stopped being counted and continued to transmit, which let primary, secondary, and congenital case counts climb every year through 2022.
- Is syphilis still increasing in 2026?
- Adult primary and secondary cases showed a 22% decline over the two years ending in 2024, per CDC's provisional 2024 surveillance report. Congenital syphilis cases were still rising into 2024 because prenatal-screening improvements take roughly nine months to show up in delivery-room data. The overall trend is improving but slowly.
- How is syphilis passed from a pregnant parent to a baby?
- Most commonly across the placenta during pregnancy, and sometimes at delivery through contact with a chancre. CDC recommends syphilis testing at the first prenatal visit, with retesting at 28 weeks and at delivery for people at higher risk. Treatment during pregnancy with penicillin can prevent congenital syphilis when given at least 30 days before birth.
- Can I test for syphilis at home?
- Yes. A home rapid test gives a result in about 15 minutes from a fingerstick drop of blood, no appointment, lab visit, or insurance step required. A reactive result needs a clinic follow-up to confirm and stage the infection before treatment starts; a non-reactive result on a routine annual check is reassuring on its own.
- Does syphilis spread before symptoms appear?
- Yes. The primary chancre is often painless and located in places people cannot see (inside the vagina, anus, or mouth), and the secondary rash is easy to mistake for a viral illness. People are highly infectious during both stages and during the first year of latent infection, even when no visible signs are present.
- Is one penicillin shot really enough to cure syphilis?
- For primary, secondary, and early latent syphilis (acquired within 12 months), yes: a single intramuscular dose of benzathine penicillin G 2.4 million units is the CDC-recommended treatment. Late latent, tertiary, and neurosyphilis require longer courses. Follow-up bloodwork at 6 and 12 months confirms the treatment worked.
- Should I still test if I am in a monogamous relationship?
- If both partners tested negative at the start of the relationship and have remained monogamous since, retesting for syphilis is not routinely necessary. If either partner has not been tested, or if the relationship started without baseline testing, screening once for both partners is reasonable. Syphilis can stay quietly latent for years after exposure.
- Where can I get a test that covers more than just syphilis?
- Combination kits screen for the most common bacterial STIs in a single test session. The 3-in-1 kit covers chlamydia, gonorrhea, and syphilis using a self-collected swab for the first two and a fingerstick blood sample for syphilis. Comprehensive multi-test kits add HIV and hepatitis tests to the panel.
- U.S. Centers for Disease Control and Prevention. STI Surveillance, annual reports including the 2024 provisional surveillance summary, used here for U.S. case-count and trend data.
- U.S. Centers for Disease Control and Prevention. 2020 STD Surveillance Report press release, used for the 7% primary and secondary syphilis rise from 2019 to 2020.
- U.S. Centers for Disease Control and Prevention. About Syphilis (CDC topic page), used for primary and secondary stage descriptions, chancre characteristics, and stage timing.
- U.S. Centers for Disease Control and Prevention. About Congenital Syphilis (CDC topic page), used for the 'more than tripled in recent years' framing and the 'nearly 4,000 cases reported in 2024, highest since 1994' headline figure.
- U.S. Centers for Disease Control and Prevention. MMWR Vital Signs: Missed Opportunities for Preventing Congenital Syphilis, United States 2022, used for the 88% missed-opportunities figure.
- U.S. Centers for Disease Control and Prevention. STI Treatment Guidelines, Primary and Secondary Syphilis section, used for the benzathine penicillin G 2.4 million units single-dose regimen.
- World Health Organization. Sexually transmitted infections fact sheet, used for global context on syphilis as one of the four curable bacterial STIs and worldwide incidence framing.
- NHS. Syphilis topic page, used for patient-facing symptom descriptions and stage-by-stage clinical framing.
