Syphilis is a bacterial infection caused by Treponema pallidum, a spiral-shaped bacterium. Often referred to as the “great imitator,” syphilis can resemble many other conditions, making diagnosis challenging. This sexually transmitted infection (STI) has a long and complex history, with ongoing debates about its origins. While once on the decline due to widespread use of penicillin, syphilis has seen a troubling resurgence in recent years, posing significant public health challenges worldwide.
What Causes Syphilis
Syphilis is caused by the bacterium Treponema pallidum. This organism is highly infectious, and exposure to as few as 500–1,000 bacteria can lead to infection. It cannot survive long outside the human body, making direct person-to-person transmission essential for infection to occur. Syphilis is most infectious during its early stages, particularly the primary, secondary, and early latent phases. If left untreated, syphilis can progress through several stages, causing severe complications over time.
How Syphilis Spreads
Syphilis is primarily transmitted through direct contact with an infected person’s sores or rashes during sexual activities, including vaginal, anal, or oral sex. Other modes of transmission include:
- From an infected mother to her unborn child during pregnancy or childbirth, leading to congenital syphilis
- Rarely, through blood transfusions or sharing contaminated needles (now very rare in countries with safe blood supply practices)
Syphilis cannot be spread through casual contact, such as hugging, sharing toilets, swimming pools, clothing, or eating utensils. Once treated effectively and any sores have healed, syphilis is no longer contagious.
Who Is at Risk of Getting Syphilis
Anyone who is sexually active can get syphilis, but certain groups are at higher risk. These include:
- Individuals with multiple sexual partners
- Men who have sex with men (MSM)
- People with HIV or other sexually transmitted infections (STIs)
- Pregnant women, who can transmit syphilis to their unborn babies
- People who engage in unprotected sex or use shared needles for drug use
Regular testing, safe sex practices, and prompt treatment are essential for preventing the spread of syphilis.
Stages of Syphilis
If left untreated, syphilis progresses through four stages, each with distinct characteristics:
- Primary Syphilis: The first visible sign is usually a small, painless sore (chancre) at the site of infection, such as the genitals, anus, or mouth. It typically appears 3–4 weeks after exposure and heals on its own within a few weeks.
- Secondary Syphilis: Weeks to months after the initial sore heals, a skin rash may develop, often on the palms and soles, along with flu-like symptoms such as fever, sore throat, and swollen lymph nodes.
- Latent Syphilis: A “hidden” stage with no symptoms. The infection remains in the body and may persist for years. During the early latent stage (within 12 months of infection), syphilis can still be transmitted. After this period, it is less likely to spread sexually but can still pass from mother to fetus.
- Tertiary Syphilis: If left untreated, syphilis can cause serious health problems years later, affecting the heart, brain, nerves, and other organs. Complications may include paralysis, blindness, and dementia.
The Modern Syphilis Challenge
Despite being curable with antibiotics like penicillin, syphilis remains a global health concern. The infection’s ability to mimic other conditions and remain symptom-free for long periods contributes to missed diagnoses and continued transmission. Syphilis also increases the risk of HIV transmission and acquisition, as both infections can amplify each other’s impact. Prompt diagnosis and treatment are crucial to prevent long-term complications and protect public health.
Current Syphilis Statistics: A Growing Concern
Recent global data shows about 50 million syphilis cases worldwide, representing a 60% increase since 1990. The World Health Organization reported 7.1 million new cases in 2020 alone, with the highest rates in:
- Sub-Saharan Africa
- Southeast Asia
- Latin America and the Caribbean
In the United States, syphilis cases have surged dramatically:
- 38% increase from 2008-2012
- 80% jump between 2018-2022
- 207,255 reported cases in 2022
Similar trends appear in Europe, with a 34% increase in cases from 2021 to 2022.
High-Risk Groups and Disparities
Certain populations face greater risks:
- Women: Cases doubled from 2013-2017, then rose another 147% by 2020
- Newborns: Congenital syphilis cases quadrupled from 2015-2019
- Young adults: Highest rates occur in people aged 20-29
- MSM population: Men who have sex with men have infection rates 214 times higher than heterosexual men
Alarmingly, about 47% of MSM with syphilis also have HIV. The connection between these infections is so strong that having one significantly increases risk for the other.
The Congenital Syphilis Crisis
Mother-to-baby transmission represents one of the most concerning trends:
- Global estimates suggest 1.5 million congenital syphilis cases annually
- U.S. rates increased tenfold over the past decade
- 2021 saw a 30% increase from 2020 rates
- Black and Hispanic infants face significantly higher rates than white infants
This resurgence highlights the need for better screening and treatment, particularly for pregnant women and high-risk groups. The coming sections will explore syphilis symptoms, diagnosis, and treatment options in detail.
Syphilis Symptoms
Syphilis develops in distinct stages, each with different symptoms. Understanding these phases helps explain why syphilis is often called the “great imitator” – its symptoms can resemble many other conditions.
Primary Syphilis: The First Signs
The initial stage typically appears 10-90 days after exposure (usually around 3 weeks). The hallmark symptom is a syphilis sore called a chancre:
- Firm, round, and painless ulcer
- Usually appears at the infection site (often genitals)
- May occur in less visible areas like the cervix or rectum
- Sometimes multiple sores appear, especially in HIV-positive patients
Even without treatment, these early stage syphilis sores heal within 3-6 weeks, but the infection remains. About 80% of patients also develop painless swollen lymph nodes near the sore.
Important: The bacteria spread throughout the body during this stage, including to the nervous system, even if no other symptoms appear.
Secondary Syphilis
If untreated, about 25% of patients develop secondary syphilis 2-8 weeks after the chancre heals. This stage involves body-wide symptoms:
- Syphilis rash (often on palms and soles)
- Fever and fatigue
- Swollen lymph nodes throughout the body
- Sore throat
- Patchy hair loss
- Muscle aches and joint pain
The syphilis rash is particularly distinctive:
- Reddish-brown spots smaller than a dime
- Often appears on palms and soles (a key identifying feature)
- Usually not itchy
- May include wart-like growths (condyloma lata) in moist areas
About 20% of patients don’t notice the rash, and all symptoms typically clear within weeks – but without treatment, the infection progresses.
A Rare but Serious Form: Malignant Syphilis
Some patients, particularly those with HIV, develop an aggressive form called lues maligna:
- Large, ulcerated sores with thick crusts
- More severe systemic symptoms
- Higher risk of treatment complications
Latent Stage: The Hidden Phase
After secondary symptoms fade, syphilis enters a hidden (latent) phase:
- No visible symptoms
- Can last for years
- Only detectable through blood tests
- About one-third progress to serious late-stage complications
Tertiary Syphilis: Late-Stage Complications
Years or decades after initial infection, untreated syphilis can cause severe damage:
- Neurosyphilis (affecting brain and nerves):
- Stroke symptoms
- Dementia-like changes
- Problems with coordination
- Cardiovascular syphilis:
- Aortic aneurysms
- Heart valve damage
- Gummatous syphilis:
- Destructive lesions in bones, skin or organs
Key Fact: About 25-40% of untreated patients develop tertiary syphilis, sometimes 20-30 years after initial infection.
Recognizing Syphilis Symptoms in Women
While syphilis symptoms in females follow the same stages, some differences are important to note:
- Initial sores often appear on internal surfaces (vagina or cervix) where they’re harder to see
- Rash may be less noticeable
- Pregnant women can pass infection to babies (congenital syphilis)
Advanced Syphilis: When the Infection Spreads
When syphilis remains untreated for years, it can affect multiple body systems with potentially severe consequences. These late-stage complications demonstrate why early syphilis treatment is so crucial.
Neurosyphilis: When Syphilis Affects the Nervous System
Syphilis can invade the nervous system at any stage, though symptoms may take years to appear:
- Early neurosyphilis (within first year):
- May cause no symptoms
- Sometimes leads to vision or hearing problems
- Late neurosyphilis (years later):
- Stroke-like symptoms
- Dementia and memory problems
- Poor coordination and balance issues
- Bladder control problems
Important: About 30% of untreated patients show spinal fluid abnormalities, but only some develop noticeable neurological symptoms.
Cardiovascular Syphilis: Damage to the Heart and Blood Vessels
This complication typically appears 10-30 years after initial infection and accounts for most tertiary syphilis cases:
- Mainly affects the aorta (heart’s main artery)
- Causes inflammation that weakens artery walls
- Can lead to aneurysms or valve problems
- May increase risk of heart attacks
Doctors often spot this through unusual calcium deposits on the aorta visible in chest X-rays. While these changes develop slowly, they can eventually cause heart failure if untreated.
Gummatous Syphilis: Growths That Damage Tissues
This rare form of late syphilis causes rubbery growths called gummas:
- Can appear on skin or internal organs
- Often affect liver, bones, or brain
- May ulcerate or form scars as they heal
- Sometimes mistaken for tuberculosis or cancer
Congenital Syphilis: When Babies Are Born Infected
Congenital syphilis occurs when mothers pass the infection to their babies during pregnancy. Despite being preventable, cases have surged in recent years.
How Congenital Syphilis Affects Pregnancy
- Can cause miscarriage or stillbirth
- Often leads to premature delivery
- May result in low birth weight
- Infected placentas are typically enlarged
Alarming Statistic: The U.S. saw a 10-fold increase in congenital syphilis cases from 2012-2022.
Recognizing Congenital Syphilis in Newborns
Many infected babies show no symptoms at birth but may develop:
- Rash (often on palms and soles)
- Yellow skin (jaundice)
- Swollen liver and spleen
- Blood abnormalities (anemia)
- Characteristic bone changes on X-rays
Later in childhood, untreated babies may develop:
- Notched teeth (Hutchinson teeth)
- Bone deformities
- Vision and hearing loss
- Neurological problems
Preventing Congenital Syphilis
Simple interventions can nearly eliminate this condition:
- Routine syphilis testing for all pregnant women:
- At first prenatal visit
- Again at 28 weeks
- At delivery for high-risk mothers
- Single penicillin injection before week 28:
- 98% effective when given early enough
- May require second dose in some cases
Key Fact: Penicillin treatment during pregnancy prevents nearly all cases of congenital syphilis when administered at least 30 days before delivery.
The next section will cover diagnosis methods and treatment options for syphilis at all stages, answering the critical question: is syphilis curable?
Diagnosing Syphilis: Tests and Procedures
Known as “the great imitator” for its wide range of symptoms, syphilis can be challenging to diagnose. As one famous physician noted, understanding syphilis means understanding much of medicine.
How Doctors Test for Syphilis
Diagnosis typically involves a two-step process:
- Initial screening test (nontreponemal):
- VDRL or RPR blood tests
- Results given as titers (e.g., 1:16)
- Useful for tracking disease progression
- Confirmatory test (treponemal):
- FTA-ABS, TPPA, or EIA tests
- Usually remain positive for life
- Don’t indicate current disease activity
New Option: The FDA recently approved an over-the-counter home syphilis test that detects treponemal antibodies. While still requiring confirmation, this may help more people get tested early.
Special Testing Situations
Additional tests may be needed for:
- Neurosyphilis:
- Spinal tap (lumbar puncture)
- CSF analysis for antibodies
- Congenital syphilis:
- Comparison of mother’s and baby’s test results
- Darkfield microscopy of suspicious lesions
Note: While syphilis is a reportable disease, many cases go unreported worldwide, making accurate statistics difficult.
Syphilis Treatment Options
The good news is that syphilis is curable with proper treatment. Penicillin remains the gold standard syphilis medication, effective at all stages.
Standard Treatment Approaches
Treatment varies by disease stage:
| Stage | Treatment |
|---|---|
| Primary, secondary, or early latent syphilis | Single injection of benzathine penicillin G (2.4 million units) |
| Late latent or tertiary syphilis | Weekly penicillin injections for 3 weeks |
| Neurosyphilis | IV penicillin for 10-14 days |
Why Penicillin Works So Well
Penicillin destroys syphilis bacteria by:
- Blocking cell wall repair enzymes
- Causing bacterial cells to burst
- Being most effective when bacteria are actively dividing
Alternative Treatments
For patients allergic to penicillin, doctors may prescribe:
- Doxycycline (100 mg twice daily for 14 days)
- Ceftriaxone (daily injections for 10-14 days)
Important: Azithromycin is no longer recommended due to growing antibiotic resistance.
After Treatment: Follow-Up Care
Post-treatment monitoring is crucial:
- Blood tests at 6, 12, and 24 months
- Additional checks at 3 and 9 months for high-risk patients
- Successful treatment shows as a 4-fold drop in antibody levels
Special Considerations
- HIV-positive patients may need longer treatment
- Neurosyphilis patients typically don’t need repeat spinal taps if blood tests improve
- Experimental treatments like linezolid show promise but aren’t yet approved
Key Fact: While newer antibiotics are being studied, penicillin remains the most effective syphilis treatment after more than 70 years of use.
Frequently Asked Questions About Syphilis
What are the first signs of syphilis?
The earliest syphilis symptoms typically appear 3-4 weeks after exposure and include a painless sore (chancre) at the infection site, often on the genitals, rectum, or mouth. Swollen lymph nodes near the sore may also occur. These syphilis sores heal on their own, but the infection persists without treatment.
Is syphilis curable?
Yes, syphilis is curable with proper antibiotic treatment. Penicillin remains the most effective syphilis medication, especially in early stages. Later stages may require more intensive treatment but can still be effectively managed.
How long does syphilis take to show up?
Early stage syphilis symptoms typically appear 10-90 days after exposure (average 3 weeks). However, some people may not notice symptoms initially, which is why regular STI testing is important for sexually active adults.
Can you get syphilis non-sexually?
While rare, syphilis can spread through direct contact with active lesions (like during kissing) or from mother to baby (congenital syphilis). Blood transfusions and needle sharing are other potential but uncommon transmission methods.
What does a syphilis rash look like?
The syphilis rash of secondary syphilis often appears as rough, reddish-brown spots on palms and soles. It’s typically not itchy and may be accompanied by flu-like symptoms. The rash can vary widely, which is why medical evaluation is crucial.
How is syphilis different from gonorrhea?
While both are STIs, syphilis progresses through distinct stages and can affect multiple body systems over years. Gonorrhea symptoms typically appear sooner (2-10 days) and primarily affect genital areas, though both require prompt treatment to prevent complications.
Conclusion
Syphilis remains a significant public health concern, with cases rising dramatically in recent years. However, this infection is both preventable and treatable. Regular STI testing, prompt treatment of infections, and safe sex practices are your best defenses. Remember that early stage syphilis is easiest to treat, so don’t delay medical attention if you notice possible syphilis symptoms or have had risky sexual exposure. With proper syphilis treatment, most people make a full recovery without long-term consequences. If you’re sexually active, consider discussing syphilis testing with your healthcare provider – it could be one of the most important health conversations you’ll have.
