Syphilis is a sexually transmitted infection caused by the bacterium Treponema pallidum. It is passed from person to person through direct contact with syphilis sores, which mainly occur on the external genitals, vagina, anus or rectum. Sores also can occur on the lips and in the mouth. Transmission occurs during vaginal, anal or oral sex. Pregnant women with the disease can transmit it to their unborn child.
Syphilis has often been called “the great imitator” because its symptoms are similar to many other diseases. The disease has a fascinating history and has impacted the lives and reputations of many famous people. Today, despite antibiotic treatment, syphilis cases are on the rise. Understanding what triggers transmission and the progression of this complex infection is an important public health goal.
Ways Syphilis is Transmitted
Syphilis spreads through direct contact with infectious sores, most often during unprotected sex. Less common ways syphilis spreads include:
– Vaginal sex. One of the most common ways to get syphilis is through vaginal sex with an infected partner. Skin-to-skin contact with syphilis sores transmits the bacteria. This can occur even if penetration does not occur.
– Anal sex. Receptive anal sex carries a high risk for syphilis transmission, as delicate tissues lining the anus and rectum can easily abrade, creating an entry point for bacteria.
– Oral sex. Oral sex with a partner with infectious syphilis sores in the mouth or on the lips can transmit the infection. Transmission is less common with oral sex than vaginal or anal sex.
– Open mouth kissing. While not highly common, direct contact between sores and lips and tongue can potentially spread syphilis.
– Mother to child. Pregnant women with syphilis can transmit the infection to the unborn child in utero. All pregnant women are recommended to be tested for syphilis.
– Shared needles. IV drug users who share needles contaminated with infected blood can transmit syphilis. This accounts for a small number of new cases.
– Blood transfusion. Syphilis transmission through blood transfusion is exceedingly rare in modern times due to comprehensive screening of the blood supply.
Symptoms and Stages of Syphilis
Syphilis occurs in four stages, each with different symptoms:
### Primary Syphilis
The first sign of infection is a painless sore at the infection site. This classically occurs 10-90 days after initial syphilis exposure, with an average of 21 days. Primary syphilitic sores last 3-6 weeks and typically heal even without treatment. Primary syphilis sore locations:
– Penis in men
– Vulva, vagina or cervix in women
– Anus or rectum
– Lips / mouth
Even after sores heal, syphilis remains in the body and progresses to the secondary stage without treatment.
Secondary Syphilis
Secondary syphilis occurs 2-10 weeks after primary sores heal, and may overlap with the later part of the primary stage. Symptoms include:
– Rash on hands and feet, often spreading to the trunk
– Fever, sore throat, fatigue and muscle aches
– Patchy hair loss
– Headaches
– Wart-like lesions around genitals and anus
The rash and lesions of secondary syphilis are highly infectious. Without treatment, symptoms resolve in 2-6 weeks but the bacteria remain in the body.
Latent Syphilis
The latent (hidden) stage occurs when symptoms resolve but the bacteria remain dormant in the body. This stage can last for years. Early latent syphilis is still infectious. After the first year, the infection progresses to late latent syphilis and is unlikely to spread to partners. Latent syphilis may never progress to tertiary syphilis. However, without treatment, about one third of latent infections eventually advance to the most serious complications.
Tertiary Syphilis
Tertiary syphilis develops in about one third of people who have untreated syphilis for many years. Symptoms can begin 10-30 years after infection was first acquired. Tertiary syphilis can seriously damage the heart, brain, eyes and other organs.
Complications of tertiary syphilis include:
– Neurosyphilis (syphilis infection of the brain and nervous system)
– Cardiovascular syphilis (infection of the heart and blood vessels)
– Gummas (soft, non-cancerous tissue growths)
Table: Stages of Syphilis Infection
| Stage | Signs & Symptoms | Infectious? | Time after exposure |
|---|---|---|---|
| Primary | Genital, anal or oral sore | Highly | 3-90 days (average 21 days) |
| Secondary | Rash, fever, sore throat, patchy hair loss | Highly | 2-10 weeks after primary |
| Latent | No symptoms | Early latent is infectious | Early latent: first year of infection |
| Late latent is not infectious | Late latent: after first year | ||
| Tertiary | Damage to heart, brain, eyes and other organs | Not infectious | 10-30 years after initial infection |
This summarizes the known stages of syphilis infection and their typical time course. However, there is considerable variability in symptom onset and duration.
Populations at Increased Risk
While anyone exposed to syphilis can become infected, certain populations have a higher incidence of the disease. Understanding the groups at elevated risk helps guide testing and preventive education efforts.
Men Who Have Sex With Men
In recent years in the U.S., over half of all primary and secondary syphilis cases have occurred among men who have sex with men (MSM). The precise reasons MSM have high rates of syphilis transmission are unclear, but likely involve multiple factors:
– Higher prevalence of syphilis within sexual networks
– More partners on average compared to exclusively heterosexual men
– Frequency of unprotected anal sex, a high transmission activity
Similarly high rates of syphilis among MSM are also seen in Canada, Europe, and Australia.
HIV-infected Persons
Those with HIV/AIDS have a 2-5 fold higher chance of contracting syphilis compared to HIV-negative individuals. Reasons for this association include:
– Similar sexual risk behaviors leading to both HIV and syphilis acquisition
– Biological interactions between the two infections that increase susceptibility
– Particularly high syphilis prevalence among MSM with HIV
Conversely, active syphilis infection also increases HIV viral load and transmission risk.
Minority Race/Ethnicity
In the U.S., syphilis rates are substantially higher among racial minorities, particularly African Americans. In 2018, the syphilis rate per 100,000 people was:
– 22.8 among African Americans
– 8.5 among Hispanics
– 5.2 among Caucasians
It is unclear the extent to which true higher biologic susceptibility versus social determinants of health contribute to these disparities.
Lower Income
Those in poverty and lacking access to health services are disproportionately affected by syphilis. Higher rates of incarceration, drug use and lack of syphilis awareness contribute to the increased burden. In one U.S. study, zip codes with median incomes below $22,000 had syphilis rates 4 times higher than zip codes with median incomes above $62,000.
Women of Reproductive Age
While smaller in absolute numbers, cases of primary and secondary syphilis are increasing at a faster rate among women compared to men. This is of particular concern, as vertical transmission from mother to fetus can have devastating health consequences. All pregnant women should be tested for syphilis.
In summary, current syphilis cases are concentrated among MSM, racial minorities, those living in poverty and HIV-infected persons. But any sexually active person with multiple partners can be exposed.
Syphilis Testing
Diagnosing syphilis requires a combination of visual inspection, microscopic examination and serologic blood testing.
Visual Exam
During the primary or secondary stages, syphilis may be diagnosed by visual inspection if typical genital or mucocutaneous lesions are present. However, many infections lack obvious symptoms.
Dark Field Microscopy
During early syphilis, swabbing a lesion and examining under a special microscope can sometimes reveal spirochetes – the corkscrew-shaped bacteria that cause syphilis. This is not routinely performed outside specialized labs.
Blood Testing
Serologic blood tests look for antibodies produced in response to syphilis infection. Two types of serologic tests are used:
Nontreponemal tests: These screen for nonspecific antibodies and include RPR (rapid plasma reagin) and VDRL (Venereal Disease Research Laboratory) tests. While helpful for screening, nontreponemal titers can fluctuate and do not reliably distinguish current from past treated infection.
Treponemal tests: These detect treponema-specific antibodies and include the TP-PA (T. pallidum particle agglutination), FTA-abs (fluorescent treponemal antibody), and newer EIAs (enzyme immunoassays). Results usually remain positive for life.
Typical syphilis testing involves initial screening with a nontreponemal test like RPR, followed by a treponemal test to confirm positive results.
Table: Syphilis Diagnostic Tests
| Test Type | Examples | Advantages | Disadvantages |
|---|---|---|---|
| Nontreponemal | RPR, VDRL | Useful for screening | Titers fluctuate, do not distinguish current/past infection |
| Treponemal | TP-PA, FTA-abs, EIA | Confirms treponema-specific antibodies | Usually remains positive for life |
| Microscopy | Dark field microscopy | Directly visualizes spirochetes | Not widely available, only detects early infection |
| Visual exam | Inspection of lesions | Rapid, inexpensive | Low sensitivity, non-specific |
This outlines the main advantages and limitations of different syphilis diagnostic methods. Sensitive and specific testing is critical for identifying and treating cases.
Syphilis Treatment
Penicillin is the only recommended treatment for all stages of syphilis.
Early Syphilis (Primary, Secondary, Early Latent)
Early infections are typically treated with:
– Single dose benzathine penicillin G 2.4 million units IM
For penicillin-allergic patients, options include doxycycline 100 mg twice daily for 14 days. Alternatively, penicillin desensitization protocols can be used to enable penicillin treatment.
Late Latent Syphilis
For late latent disease of unknown duration:
– Benzathine penicillin G 2.4 million units IM for 3 doses at 1 week intervals
Tertiary Syphilis
Tertiary syphilis requires more intensive therapy:
– Benzathine penicillin G 2.4 million units IM for 3 doses weekly for 3 consecutive weeks
(total 7.2 million units over 3 weeks)
Treatment is usually ineffective at reversing late stage complications like neurosyphilis or cardiovascular syphilis.
Special Considerations
– Pregnant women require additional treatment to prevent congenital syphilis
– All patients should be re-tested after 3-6 months to confirm cure
– Patients should avoid sex until treatment is complete
In summary, parenteral benzathine penicillin G is the sole recommended therapy for syphilis at all disease stages. Treatment later in disease may prevent progression but cannot reverse damage sustained over years of infection.
Syphilis Prevention
Primary prevention of syphilis involves:
Safer Sex Practices
– Using condoms or other barriers to prevent contact with syphils sores
– Minimizing partners and avoiding concurrent partners
– Not sharing sex toys that could spread infectious secretions
Testing and Treatment
– Testing sexually active adults annually if at risk, and more frequently if engaging in high risk behaviors
– Timely diagnosis and treatment of infected individuals and partners
– Screening all pregnant women to prevent congenital syphilis
Addressing Social Determinants of Health
– Focusing prevention and testing efforts among highest risk groups
– Increasing syphilis awareness through provider and community education
– Fighting poverty, improving access to medical care and reducing mass incarceration
With continued safer sex practices, partner management, and addressing social factors that increase syphilis susceptibility, the rising case counts can be reversed.
Conclusion
Syphilis remains a major public health threat, with increasing case reports, particularly among men who have sex with men. However, this complex systemic infection is also a fascinating historical disease that has puzzled doctors and researchers for centuries. Its variable presentation and long latency period provide management challenges.
Key points include:
– Syphilis transmission occurs through direct contact with infectious lesions, primarily during sexual contact
– The hallmark symptom is a painless ulcer at the infection site, classically on the genitals
– Without treatment, syphilis progresses through primary, secondary, latent and tertiary stages
– While primary and secondary syphilis are most infectious, all stages require antibiotic treatment, typically with intramuscular benzathine penicillin injections
– Safer sexual practices, testing, partner management and addressing social determinants can control ongoing spread
After decades of decline, syphilis has re-emerged globally as an important health condition. However, with continued vigilance and prompt diagnosis and treatment, syphilis-related complications can be minimized. This complex multi-system infection will likely continue to intrigue and challenge physicians in the years to come.