A-Z of Syphilis: All You Need to Know

Syphilis is a sexually transmitted infection that has plagued humanity for centuries. Caused by the bacterium Treponema pallidum, syphilis can cause serious health issues if left untreated. 

In this guide, we will examine what syphilis is, how it spreads, its signs and symptoms, stages of progression, diagnosis methods, and strategies for prevention. Understanding this insidious STI can help curb its transmission and reduce associated harms.

What is Syphilis?

Syphilis is classified as a sexually transmitted infection (STI) because it is primarily transmitted through unprotected sexual contact like vaginal, anal, or oral sex. The causative agent is Treponema pallidum, a type of spiral-shaped bacterium that enters the body through breaks in the skin or mucous membranes during sex with an infected person. 

From there, it can spread systemically through the bloodstream. While syphilis requires direct contact with sores or lesions for transmission, proper condom use helps reduce the risk when sores are present.

How is Syphilis Transmitted?

The primary route of syphilis transmission is through sexual contact with an infected person. There are, however, other modes of syphilis transmission:

Sexual Contact

Direct contact with infectious syphilitic sores or lesions during vaginal, anal, or oral sex accounts for the vast majority of transmissions. The sores found during primary and secondary infection contain concentrated forms of T. pallidum bacteria that readily pass between partners. Concurrent ulcers from other STIs may also facilitate transmission.

Mother-to-Child

Congenital syphilis – transmission from an infected mother to her foetus – remains a significant concern. Untreated maternal syphilis can spread the spirochetes across the placenta at any point during pregnancy or delivery. This puts newborns at risk of deformities, organ damage, or stillbirth if left unaddressed. Timely screening and treatment of at-risk mothers is therefore crucial.

Window Period & Asymptomatic Carriers  

During primary infection or latency, when symptoms are absent, individuals may still transmit syphilis due to high bacterial loads in genital secretions or blood. This underscores the need for comprehensive STI testing of sexually active individuals and partners of those diagnosed. Some long-term carriers remain infectious for life without proper therapy.

Influence of Other Factors

While contact with sores carries the most significant risk, transmission is theoretically possible via oral/vaginal/anal secretions during any stage due to persistent T. pallidum bacteremia. Conditions like mucosal trauma, co-infection with HIV, viral STIs, or phimosis can further enhance contagiousness.

Signs and Symptoms 

Syphilis signs and symptoms vary depending on the stage of infection. Early signs may include fever, swollen lymph nodes, hair loss, headaches, fatigue, and muscle aches. However, laboratory tests are needed for diagnosis since these signs are non-specific.

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Stages of Syphilis

Syphilis progresses through three main stages – primary, secondary, latent, and tertiary – if left untreated:

1. Primary Stage (3 weeks post-infection)

The initial chancre sore develops 10-90 days after exposure, usually as a single lesion but occasionally in multiple locations. It appears as a firm, painless, non-itchy ulcer with a clean base and raised borders, ranging from 0.3-3cm in diameter. Regional lymphadenopathy is common. The sore will self-resolve within 3-6 weeks, regardless of therapy.

2. Secondary Stage (2-6 weeks later)

A non-itchy rash may emerge on the trunk and extremities rather than just the palms/soles. This rash, known as roseola syphilitica, consists of small, scattered macules that are oval, circular, or polygonal in shape. Other cutaneous manifestations include condyloma lata – moist, flat-topped warts that develop in warm, damp areas such as the groin and perineum. Mucocutaneous involvement presents as diffuse, gray-white lesions of the oral cavity, genitals, or anal region.  

3. Latent Stage

The latency period merits particular examination. During this time, T. pallidum circulates at low levels in bodily fluids while evading immune detection through antigenic variation of its surface proteins. Neuroinvasion may occur early on via hematogenous spread, with 10-15% of cases ultimately resulting in neurosyphilis if left untreated. 

4. Tertiary stage (years later)

Untreated syphilis may cause severe complications as the spirochete damages internal organs over decades, risking meningitis, stroke, and gummas.

Diagnosis

Early and accurate diagnosis of syphilis is crucial to effective treatment and prevention of further spread. As syphilis signs and symptoms are often non-specific in the initial stages, laboratory tests provide the only definitive way to identify infection. Here, we will examine the various diagnostic methods in more detail:

Screening Tests

The first-line screening tests for syphilis are the non-treponemal VDRL (Venereal Disease Research Laboratory) and RPR (Rapid Plasma Reagin) tests. These detect nonspecific reaginic antibodies produced in response to T. pallidum infection. While very sensitive, they can yield false positives in cases of other medical conditions or drug use. If positive, confirmation is still needed.

Treponemal Tests

More specific treponemal tests like FTA-ABS (Fluorescent Treponemal Antibody Absorption) and MHA-TP (Microhemagglutination Assay for Treponema pallidum) identify antibodies produced exclusively in reaction to T. pallidum. 

These are used to confirm non-treponemal test results or diagnose neurosyphilis when the latter may be harmful. FTA-ABS uses fluorescently labeled antibodies to detect reactivity, while MHA-TP detects agglutination of dyed, antigen-coated sheep red blood cells.

Darkfield Microscopy

Considered the gold standard direct test, darkfield microscopy allows the visualization of live, motile T. pallidum spirochetes in fluid samples from syphilitic lesions, blood, or cerebrospinal fluid. This confirms active infection but requires specialized equipment and trained technicians. Spirochetes may be challenging to find if present in low numbers.

Other Tests

Polymerase chain reaction (PCR) testing of lesion samples offers susceptible detection of T. pallidum DNA. Cerebrospinal fluid analysis checks for abnormalities indicating neurosyphilis. Prenatal maternal screening helps identify untreated cases and prevent congenital syphilis. Together, these diagnostic modalities provide clinicians with multiple options to confirm syphilis reliably.

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Treatment

Penicillin remains the first-line treatment for all stages of syphilis due to its effectiveness in killing T. pallidum. For primary, secondary, and early latent syphilis, benzathine penicillin G is administered via intramuscular injection at one of two dosage schedules based on the clinical stage. Doxycycline and tetracycline are oral alternatives for those with penicillin allergies.

Treatment is essential not just to stop disease progression but also to prevent onward transmission to partners. Individuals must abstain from sex for the entire course of therapy to ensure non-infectiousness. Pregnant women receive penicillin to prevent congenital syphilis in the fetus as well. 

While treatment cures the infection, it does not undo any existing organ or tissue damage from earlier stages. Therefore, prompt diagnosis and compliance with the entire treatment regimen are paramount. Clinical and serological follow-up helps monitor for reinfection.

Complications

Untreated syphilis raises risks of:

• Neurosyphilis: Bacteria spread to the brain/spinal cord, causing meningitis.  
• Ocular Syphilis: Can impair vision or cause blindness.
• Cardiovascular Syphilis: Leads to aortic aneurysms or narrowing of large arteries.
• Gummas: Fleshy tumor-like lesions affecting internal organs or bones.

Early screening and compliance with medication regimens help prevent such complications from developing.

Preventive Measures

Given syphilis’s formidable modes of spread, prevention requires a comprehensive strategy incorporating behavioral and biomedical aspects:

Consistent Condom Use

Latex condoms, when used correctly from start to finish of all sexual acts, can reduce transmission risk due to syphilis sores by up to 90%, according to some studies. However, skin-to-skin contact risk remains during outbreaks.

Screening and Treatment  

Routine STI screening helps identify asymptomatic infections for timely treatment, thus curbing onward spread. All partners of diagnosed individuals should undergo clinical evaluation and receive prophylactic antibiotics when recommended.

Health Education

Comprehensive sexuality education empowers youth and adults to make informed choices regarding sexual health. Targeted awareness programs can also reach at-risk demographics like men who have sex with men. 

Access to Healthcare

Readily accessible screening, treatment, and prevention services help communities implement a consistent public health response against syphilis outbreaks. This includes maternal syphilis elimination programs.

Conclusion

Syphilis is a serious STI that can damage the body if left unchecked. However, with the proper understanding of causes, signs, stages, testing, and prevention strategies, communities stand a better chance of curbing its spread. Individuals also gain the knowledge to make informed choices regarding their sexual health and that of their partners.