STIs Overview: Chlamydia, Gonorrhea, and Syphilis Management

Every year, millions of people get infected with chlamydia, gonorrhea, or syphilis - three of the most common bacterial sexually transmitted infections (STIs). These aren’t just minor health issues. Left untreated, they can lead to infertility, life-threatening complications, and even pass from mother to baby during pregnancy. The good news? We know how to find and treat them. The challenge? Many people don’t know they’re infected, and antibiotic resistance is making some cases harder to cure.

Why These Three STIs Matter

In 2021, the CDC reported over 2.5 million cases of chlamydia, gonorrhea, and syphilis combined in the U.S. alone. Half of those cases were in people aged 15 to 24. That’s not because younger people are more likely to have sex - it’s because they’re less likely to get tested. Chlamydia is the most common, with 129 million new cases globally in 2020. Gonorrhea comes second. Syphilis, while less common, is rising fast - especially among pregnant women. Congenital syphilis cases in the U.S. jumped 273% between 2017 and 2021. That’s a public health emergency.

What makes these infections dangerous isn’t just how they spread - through vaginal, anal, or oral sex - but how quietly they do it. Up to 95% of women and half of men with chlamydia feel nothing. No pain. No discharge. No warning. The same goes for gonorrhea. By the time symptoms show up, damage may already be done. Syphilis is sneakier. It moves in stages, sometimes hiding for years before causing heart or brain damage.

Chlamydia: The Silent Epidemic

Chlamydia is caused by Chlamydia trachomatis a bacterium that infects the cervix, urethra, rectum, and throat. It’s called a silent epidemic because most people never know they have it. When symptoms do appear, they’re mild: unusual discharge, burning during urination, or bleeding between periods. In women, untreated chlamydia can lead to pelvic inflammatory disease (PID). About 10-15% of infected women develop PID, which can scar the fallopian tubes and cause infertility or ectopic pregnancy.

Testing is simple. A urine sample or swab from the vagina, rectum, or throat can detect it. No blood work needed. Treatment is straightforward: either a single dose of azithromycin (1 gram) or a week of doxycycline (100 mg twice daily). Cure rates are above 95% if taken correctly. But here’s the catch: 14-20% of young women get reinfected within a year. Why? Their partners weren’t treated. That’s why the CDC says: if you’re diagnosed, your last sexual partner from the past 60 days needs to be treated too - even if they feel fine.

There’s also a new tool: doxycycline post-exposure prophylaxis (DoxyPEP). Taking a single 200 mg pill within 72 hours after condomless sex cuts chlamydia risk by 60% in men who have sex with men and transgender women on PrEP. But it doesn’t work the same way for cisgender women. So far, evidence doesn’t support using it there.

Gonorrhea: The Resistant Threat

Neisseria gonorrhoeae the bacterium causing gonorrhea, known for rapidly evolving resistance to antibiotics is becoming harder to kill. Once treated with simple pills, now it often requires a shot plus a pill. The CDC’s current recommendation is a 500 mg injection of ceftriaxone plus 1 gram of azithromycin. But even this combo is failing in some places. In parts of the U.S. and Europe, up to 50% of gonorrhea strains are now resistant to azithromycin.

Symptoms are similar to chlamydia: pus-like discharge, painful urination, sore throat, or rectal discomfort. But gonorrhea is more likely to spread beyond the genitals. About 1 in 50 people develop disseminated gonococcal infection (DGI) - a rare but serious condition that causes fever, joint pain, and skin lesions. It can be fatal if not treated fast.

Testing uses the same swabs or urine samples as chlamydia. But here’s a key difference: if you have a throat infection, you need a follow-up test two weeks after treatment. Cure rates are lower in the throat than in the genitals - up to 10% fail to clear the infection without retesting.

The good news? A new drug called zoliflodacin is in phase 3 trials and shows 96% effectiveness. It’s expected to get FDA approval by 2025. This could be a game-changer, especially since the pipeline for new antibiotics is nearly empty. The CDC calls gonorrhea an “urgent threat” - not because it’s deadly, but because we’re running out of ways to treat it.

Syphilis: The Great Imitator

Treponema pallidum the spiral-shaped bacterium responsible for syphilis, known for its multi-stage progression and ability to mimic other diseases doesn’t just infect - it evolves. It moves through four stages, each with different symptoms, and can lie dormant for years.

• Primary syphilis: One painless sore (chancre) appears at the infection site - usually genitals, anus, or mouth - 10 to 90 days after exposure. It heals on its own, but the infection doesn’t.
• Secondary syphilis: Weeks later, a rash (often on palms and soles), fever, swollen glands, and fatigue appear. Hair loss and sores in the mouth or anus can happen too. Again, symptoms fade - but the bacteria keep spreading.
• Latent syphilis: No symptoms. This stage can last for years. Blood tests still show the infection.
• Tertiary syphilis: Decades later, it attacks the heart, brain, nerves, and bones. This can lead to stroke, dementia, blindness, or death.

Diagnosis is always through blood tests. No swabs or urine. Two types of tests are used: non-treponemal (like RPR) to check activity, and treponemal (like EIA) to confirm past or current infection. If someone is pregnant, they must be tested at first prenatal visit and again at 28 weeks in high-risk areas. Congenital syphilis can cause stillbirth, premature birth, or severe birth defects.

Treatment depends on the stage. Early syphilis (primary, secondary, or early latent) gets one shot of benzathine penicillin G (2.4 million units). Late syphilis needs three shots, one per week. If you’re allergic to penicillin, alternatives exist but are less reliable. That’s why penicillin remains the gold standard.

Prevention and Public Health Gaps

Condoms reduce chlamydia and gonorrhea transmission by 60-90% and syphilis by 50-70%. But they’re not foolproof - especially if not used every time. Regular testing is the real shield. The CDC recommends yearly chlamydia and gonorrhea screening for all sexually active women under 25, and for older women with new or multiple partners. Men who have sex with men should be tested at least yearly - and every 3-6 months if they have multiple partners.

There’s a deep racial disparity here. Black Americans have chlamydia rates 5.6 times higher, gonorrhea rates 6.7 times higher, and syphilis rates 3.5 times higher than White Americans. Why? Lack of access to care, stigma, underfunded clinics, and systemic barriers - not behavior differences.

The WHO’s 2021-2030 Global STI Strategy aims to cut syphilis in pregnant women by 90% and chlamydia/gonorrhea by 70%. That’s ambitious. But it’s possible - if we invest in testing, partner services, and education.

What You Need to Do

• If you’re sexually active, get tested at least once a year - more if you have new partners.
• Ask for testing even if you feel fine. No symptoms doesn’t mean no infection.
• If you’re diagnosed, tell your partners. They need to get treated too.
• Don’t skip follow-up tests. Retesting at 3 months after chlamydia treatment catches reinfection early.
• Use condoms consistently. They’re not perfect, but they’re the best tool we have.
• If you’re on PrEP, ask your doctor about DoxyPEP - if you’re a man who has sex with men or a transgender woman.

The bottom line: these infections are preventable. Treatable. But only if we act. Ignoring them doesn’t make them go away - it just makes them spread.