Published: August 2025 | Last updated: April 2026
Syphilis cases in the United States have climbed to a level not seen in roughly seven decades, with congenital syphilis (passed from a pregnant person to a newborn at delivery) rising sharply alongside the adult numbers. Gonorrhea earned a spot on the World Health Organization's high-priority drug-resistant pathogens list because some strains now resist nearly every antibiotic in the front-line playbook. Chlamydia is still the most-reported bacterial sexually transmitted infection on the planet, often spreading silently for months before a single symptom shows up.
The infections your grandparents feared did not vanish. They came back with tougher genetics, weaker public-health funding to chase them down, and new transmission patterns shaped by hookup apps, lower condom use, and clinic closures. This article explains why the classic STDs are resurging, what antibiotic resistance has changed about treatment, what each infection looks like in 2026, and where routine at-home or clinic testing fits in. The good news: every infection covered here is still detectable, and most are still curable. The bad news: catching them early matters more than at any point since penicillin first arrived in the 1940s.
Are old STDs really making a comeback?
Yes. Syphilis, gonorrhea, and chlamydia are all climbing again in the United States and across Europe. The U.S. <a href="https://www.cdc.gov/sti-statistics/" target="_blank" rel="noopener">CDC's national STI surveillance summary</a> reported more than 2.4 million combined cases of those three infections in 2022, with primary and secondary syphilis at the highest reported rate in roughly 70 years. Antibiotic resistance has made gonorrhea harder to treat, but every classic STD in this article is still curable when caught early. The highest-impact action: test once a year if you are sexually active, every 3 to 6 months if you have new or multiple partners.
Why classic STDs are surging again
Several forces stacked on top of each other in the last fifteen years and the result is the resurgence we see now. None of them is a single villain; together they explain why infections once thought near-eliminated are back in routine clinical care.
- Antibiotic resistance. The bacteria that cause gonorrhea (Neisseria gonorrhoeae) have evolved past nearly every antibiotic class doctors have thrown at them. WHO's drug-resistant gonorrhoea fact sheet documents resistance to penicillins, tetracyclines, sulfonamides, macrolides, and fluoroquinolones, with reduced susceptibility to the current ceftriaxone-based first-line treatment now reported in multiple countries.
- Public-health funding cuts. Many U.S. STI clinics have closed or reduced hours over the last decade. Fewer free or low-cost screening doors mean infections circulate longer before anyone catches them.
- Lower condom use. Survey data show condom use has declined among younger U.S. adults, particularly with the spread of HIV pre-exposure prophylaxis (PrEP), which protects against HIV but not against bacterial STDs.
- Dating apps and shifting sexual networks. More partners reachable per unit time means infections can spread further before symptoms (or any symptoms at all) prompt testing.
- Stigma and missed asymptomatic cases. Most chlamydia and a substantial share of gonorrhea infections cause no obvious symptoms. People who feel fine usually do not test, and the infection silently moves on.
The pattern is familiar: a medical advance (penicillin in the 1940s) creates an era of confidence, public-health investment slips, behavior shifts, and the bacteria evolve. None of those forces alone would produce a 70-year-high syphilis curve.
This article is published by stdrapidtestkits.com, which sells at-home STI testing kits. We recommend products based on what fits the reader's situation, not commercial benefit. Where a clinic visit (or lab confirmation of a positive home test) is the right next step, we say so.
How antibiotic resistance happened
The 1940s arrival of penicillin was the most consequential moment in the history of treating bacterial STDs. Syphilis death rates collapsed within a decade. Gonorrhea, which had been a chronic and disabling infection, became a five-day course of pills. Doctors of that era could reasonably believe these diseases would be eradicated within a generation.
That confidence drove decades of overprescription. Antibiotics were handed out for viral illnesses they could not treat, given without confirmatory cultures, dispensed without prescriptions in some countries, and stopped early by patients who felt better after three days of a seven-day course. Each of those moments gave bacterial populations a chance to evolve. The bacteria that survived a partial dose were the bacteria that reproduced, and the genetics of resistance accumulated.
Gonorrhea is the headline example because it acquires resistance fastest. The U.S. CDC's gonorrhea topic pages describe a roughly 80-year arc in which sulfonamides, penicillins, tetracyclines, fluoroquinolones, and macrolides each entered first-line use, then dropped out as resistance spread. The current standard is a single intramuscular injection of ceftriaxone, and even that drug now shows reduced susceptibility in scattered case reports from Asia, Europe, and (more recently) the U.S.
Syphilis is a different organism with different resistance dynamics. Treponema pallidum, the bacterium that causes syphilis, has so far stayed susceptible to penicillin G, the standard treatment for more than 75 years. The reason syphilis is at modern peaks is not that the antibiotic stopped working; it is that infected people are not being diagnosed in time to treat. Resistance to azithromycin (a back-up syphilis treatment for penicillin-allergic patients) is now widespread, but penicillin G itself remains the gold standard.
Chlamydia trachomatis, the bacterium behind chlamydia, has occasional resistance reports but has not yet developed the population-level resistance gonorrhea has. Doxycycline and azithromycin still work for the vast majority of cases. The challenge with chlamydia is mostly diagnostic: it is so often silent that people do not know to take any treatment in the first place.
Syphilis: the renaissance disease back at modern peaks
Syphilis has one of the strangest documented histories of any infection. It exploded across Europe in the 1490s, picked up nicknames like "the Great Pox," and devastated populations that had no effective treatment for the next 450 years. By the late 20th century, U.S. cases had dropped so low that public-health officials briefly debated whether elimination was within reach.
That conversation is over. Per CDC surveillance data through 2023, primary and secondary syphilis are at the highest reported rates since the 1950s, and the U.S. CDC's syphilis topic pages note congenital syphilis (transmitted in utero or during birth) up sharply over the last decade with infant deaths from the infection rising in parallel.
Syphilis progresses in distinct stages, and each one looks different:
- Primary syphilis. A single painless sore (a chancre) appears at the site of infection, typically 10 to 90 days after exposure. It heals on its own in three to six weeks, which is part of why people miss it. "It went away" does not mean the infection went away.
- Secondary syphilis. Weeks to months later, a non-itchy rash appears, often on the palms and soles, sometimes accompanied by mild fever, swollen lymph nodes, and patchy hair loss. This stage also resolves without treatment, while the bacteria continue to circulate.
- Latent syphilis. No outward symptoms. The infection is still present and can be passed during pregnancy or, less commonly, through blood.
- Tertiary syphilis. Years to decades later, untreated infection can damage the heart, brain, nerves, eyes, and other organs. Tertiary syphilis is rare today in countries with widespread testing, but it is what made syphilis terrifying historically.
Penicillin G still cures every stage when given correctly, but treatment cannot reverse damage already done. That is the whole argument for testing during routine sexual-health screening rather than waiting for symptoms.
Gonorrhea ("the clap") and the superbug threat
Gonorrhea has been documented in medical writing since at least the Greek physician Galen in the 2nd century. "The clap" nickname dates from the medieval period and the symptom set is barely changed: painful urination, unusual discharge, and inflammation in the urethra, cervix, throat, or rectum depending on exposure site. What is changing is what happens after diagnosis.
Per the U.S. CDC's clinical guidance on gonorrhea (2021 treatment update), the current standard for uncomplicated infection is a single 500 mg intramuscular injection of ceftriaxone. That is the third or fourth first-line drug class in roughly 80 years, because each previous class lost effectiveness as resistance spread. The bacterium acquires resistance unusually fast: through chromosomal mutations, through plasmid-mediated mechanisms, and by recombining genetic material with related Neisseria species in the throat.
What this means in practice:
- Throat infections matter more than they used to. Pharyngeal (throat) gonorrhea is often asymptomatic, harder to treat, and a common site where resistance evolves. The U.S. CDC clinical guidance specifically notes throat infections require careful follow-up to confirm cure.
- Failed treatment is a flag, not a setback to ignore. If symptoms persist a week after treatment, that is a clinical signal of possible resistance and a reason to return to the prescribing clinic for repeat culture and susceptibility testing.
- Annual screening is now standard for sexually active women under 25, and for older women with new or multiple partners. CDC also recommends annual screening at all anatomical exposure sites for sexually active men who have sex with men.
Many gonorrhea infections cause no symptoms, particularly in the throat and rectum, so screening picks them up before complications do. One scope note worth surfacing: our at-home gonorrhea test is a rapid lateral-flow swab kit using the same self-collected sample type clinics use for first-line genital screening. We do not sell pharyngeal (throat) or rectal swab kits. If your exposure was oral or anal, a clinic visit for a site-specific swab (and, if positive, a culture-based susceptibility test) is the right path. Lateral-flow rapid screening is a useful first step, not a replacement for a culture when treatment-resistance status matters.
Antimicrobial resistance in gonorrhoea has increased rapidly in recent years and has reduced the options for treatment.
Chlamydia: the silent epidemic
Chlamydia is the most-reported bacterial STI in nearly every country that tracks the data. The U.S. CDC's chlamydia topic pages describe over a million reported cases annually in the U.S., and the CDC notes that chlamydia often produces no symptoms at all, so the true number of infections is almost certainly higher than what gets diagnosed and reported.
Chlamydia trachomatis, the bacterium responsible, has been infecting people for thousands of years, but it was only formally identified in the 20th century. The infection is often called "silent" because many people, particularly women, have no symptoms. Without symptoms, there is no prompt to test, and the bacterium quietly moves on to new partners.
The complications are not silent. In women, untreated chlamydia ascends from the cervix into the upper reproductive tract and causes pelvic inflammatory disease (PID), which can scar the fallopian tubes. PID is one of the leading preventable causes of tubal infertility and ectopic pregnancy. In men, untreated chlamydia can cause epididymitis (a painful inflammation near the testicle) and, less commonly, fertility problems. In newborns delivered through an infected birth canal, chlamydia can cause conjunctivitis and pneumonia.
Treatment is straightforward: a 7-day course of doxycycline (or a single dose of azithromycin in specific situations) clears the infection in nearly every case. Resistance is rare. The CDC recommends annual chlamydia screening for all sexually active women under 25 and for older women with new or multiple partners. The same recommendation applies to sexually active men who have sex with men, with screening at each anatomical exposure site.
Most chlamydia infections produce no obvious symptoms, especially in women. Untreated infection can ascend into the upper reproductive tract and cause pelvic inflammatory disease (PID), which is a leading preventable cause of tubal infertility and ectopic pregnancy. The U.S. CDC's annual screening recommendation for sexually active women under 25 is the single most consequential prevention step, because it catches infections during the silent window before complications start.
Mycoplasma genitalium and other newer resistance threats
Not every STI in the resurgence story is centuries old. Mycoplasma genitalium (often abbreviated Mgen) was identified in the early 1980s and is now recognized as a meaningful cause of urethritis in men, cervicitis in women, and a contributor to PID. The U.S. CDC STD Treatment Guidelines for Mycoplasma genitalium describe rapidly increasing resistance to azithromycin, the historical first-line drug, and recommend moxifloxacin (typically a 14-day course of moxifloxacin 400 mg orally daily) for confirmed macrolide-resistant infections.
Mgen is harder to test for than chlamydia or gonorrhea. The diagnosis usually requires nucleic-acid amplification testing in a clinical lab, and treatment is increasingly a multi-step process based on susceptibility results.
The broader pattern matters: bacterial STIs do not stay frozen in their treatment-era state. The classic three (chlamydia, gonorrhea, syphilis) plus Mgen, taken together, are why routine screening, completing every prescribed course of antibiotics, and partner notification are not optional public-health rituals; they are the only tools that slow the resistance curve.
If you have persistent urethritis (in men) or cervicitis (in women) that did not clear after standard treatment for chlamydia or gonorrhea, ask a clinician specifically about Mycoplasma genitalium testing. Diagnosis requires a clinical-lab nucleic-acid amplification test (NAAT). At-home rapid lateral-flow kits, including ours, are not validated for this organism and a negative panel does not rule it out.
Rare historical STDs that still circulate
The headline three (chlamydia, gonorrhea, syphilis) account for the overwhelming majority of bacterial-STI cases in high-income countries, but several historical infections still circulate, and global travel keeps them showing up in unexpected places. They are uncommon enough that many clinicians may not recognize them on first look.
| Infection | Where it is most common today | Key signs | Often confused with |
|---|---|---|---|
| Chancroid (Haemophilus ducreyi) | Parts of Africa and Asia, sporadic in the U.S. | Painful soft genital ulcer, often with tender swollen lymph nodes in the groin | Genital herpes, primary syphilis (which is painless) |
| Lymphogranuloma venereum (LGV) | Tropical regions historically, rising again in Europe and North America among men who have sex with men | Small painless genital ulcer, then markedly swollen tender lymph nodes; rectal infection can cause severe proctitis | Inflammatory bowel disease, anal fissure, other proctitis causes |
| Donovanosis (granuloma inguinale) | Parts of India, southern Africa, Papua New Guinea; rare in the U.S. | Slow-growing painless beefy-red ulcers that bleed easily on contact | Genital cancer, late-stage syphilis, atypical mycobacterial infection |
How to protect yourself
The strategy has not changed much since the late 20th century. What has changed is how easily each piece of it can be done from home.
- Test routinely, not only when worried. The U.S. CDC recommends at least annual screening for sexually active women under 25, for sexually active men who have sex with men, and for anyone with new or multiple partners. Every 3 to 6 months is appropriate for higher-risk situations.
- Use external (or internal) condoms and dental dams consistently. They reduce transmission of every infection covered here, although they do not eliminate the risk of skin-to-skin infections like syphilis and herpes that can be transmitted from areas the condom does not cover.
- Finish every prescribed antibiotic course, even if you feel fine after three days. Stopping early is one of the strongest drivers of resistance. The bacteria most likely to survive a partial course are the bacteria that pass on resistance traits.
- Notify partners after a positive result. This is the single highest-impact public-health action a person with a positive test can take. Many U.S. health departments offer anonymous partner-notification services if a direct conversation feels too hard.
- Confirm and treat positives through a clinician. A reactive at-home result is a screening signal, not a final diagnosis. Lab confirmation and a prescription for the correct antibiotic at the correct dose is what actually clears the infection.
- Talk to your provider about HPV and hepatitis B vaccination. Two of the few sexual-health threats that have working vaccines, both with strong real-world impact data.
Which kit fits which situation
The right at-home test depends on the exposure, the symptom picture, and how many infections you want to cover at once. A rough decision tree:
- One specific concern after a known exposure: a single-infection rapid test (chlamydia, gonorrhea, syphilis, HIV) is the cheapest and fastest answer for that one question.
- New partner, no symptoms, want a baseline check: a 2-in-1 chlamydia + gonorrhea swab covers the two most-co-occurring bacterial STIs.
- Comprehensive screen, multiple partners or after a longer gap since last test: a 6-in-1 or 7-in-1 combination kit covers the bacterial swab tests plus the blood-borne fingerstick tests in a single panel.
For any of these, a reactive result is the start of the conversation, not the end. Lab confirmation and a clinician-supervised treatment plan, including the right antibiotic at the right dose for the right duration, is what clears the infection and slows the resistance curve for everyone else.
Frequently asked questions
- Are old STDs really making a comeback?
- Yes. Primary and secondary syphilis cases in the U.S. have climbed to their highest reported rate in roughly 70 years per CDC surveillance data through 2023, and congenital syphilis (transmitted from a pregnant person to a newborn at delivery) is rising fastest. Annual screening for sexually active adults catches most resurgent infections before complications start.
- What is "super gonorrhea" and should I be worried?
- "Super gonorrhea" is the informal name for gonorrhea strains resistant to multiple antibiotic classes, including reduced susceptibility to ceftriaxone (the current first-line drug). Cases are uncommon but documented in Asia, Europe, and the U.S. The practical takeaway is to complete every prescribed antibiotic course, return to the clinic if symptoms persist a week after treatment, and get re-tested after treatment for any throat or rectal infection.
- Does penicillin still cure syphilis?
- Yes. Penicillin G has remained the first-line treatment for every stage of syphilis since the 1940s, and Treponema pallidum (the bacterium that causes syphilis) has not developed meaningful penicillin resistance. The reason syphilis cases are at modern peaks is that infections are not being diagnosed and treated in time, not that the antibiotic stopped working.
- Can chlamydia really cause infertility if untreated?
- Yes. PID from untreated chlamydia is one of the most preventable causes of blocked fallopian tubes and ectopic pregnancy. Because the infection is silent in most women, the damage accumulates without any prompt to treat. In men the main risk is epididymitis. Annual screening is the single highest-impact intervention because it catches the infection before any of this starts.
- How often should I get tested for STIs?
- The U.S. CDC recommends at least annual chlamydia and gonorrhea screening for all sexually active women under 25, and for older women with new or multiple partners. Sexually active men who have sex with men should screen at least annually at every anatomical exposure site. Anyone with a new partner has a reasonable case for testing. People at higher risk (multiple partners, condomless sex, partners with known STIs) should test every 3 to 6 months.
- Can condoms fully prevent these infections?
- Condoms greatly reduce transmission of every infection covered in this article, but they do not eliminate the risk completely. Syphilis and herpes can be passed by skin-to-skin contact in areas the condom does not cover. The strongest protection is condoms used consistently plus routine screening plus open conversation with partners. None of those tools alone is enough.
- What is Mycoplasma genitalium and how is it different?
- Mycoplasma genitalium (Mgen) is a more recently identified bacterial STI that causes urethritis in men, cervicitis in women, and contributes to pelvic inflammatory disease. It is harder to test for (most diagnosis requires lab nucleic-acid testing), and resistance to azithromycin (the historical first-line drug) is now common; CDC treatment guidelines now recommend moxifloxacin for confirmed macrolide-resistant infections. People with persistent urethritis or cervicitis after standard treatment for chlamydia and gonorrhea should ask a clinician specifically about Mgen testing.
- If I test positive at home, what should I do next?
- Treat a reactive at-home result as a screening signal, not a final diagnosis. The next steps: contact a clinician for confirmatory lab testing (often the same sample type), get the right antibiotic at the right dose, finish the entire course, notify recent sexual partners so they can test, and avoid sex until both you and your treated partners have completed treatment and any recommended follow-up.
- U.S. Centers for Disease Control and Prevention. National STI surveillance summary, including current syphilis, gonorrhea, and chlamydia case counts and historical context.
- U.S. Centers for Disease Control and Prevention. Gonorrhea topic pages, including clinical treatment guidance and antibiotic resistance background.
- World Health Organization. Multi-drug resistant gonorrhoea fact sheet, including antimicrobial resistance trends and global treatment implications.
- U.S. Centers for Disease Control and Prevention. Syphilis topic pages, including stage-by-stage clinical features, congenital syphilis trends, and screening recommendations.
- U.S. Centers for Disease Control and Prevention. Chlamydia topic pages, including incidence data, complications, and screening recommendations.
- U.S. Centers for Disease Control and Prevention. STD Treatment Guidelines for Mycoplasma genitalium, including azithromycin resistance trends and moxifloxacin treatment recommendations.
