How is syphilis transmitted?

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From the Guidelines

Syphilis is primarily transmitted through direct contact with a syphilis sore during vaginal, anal, or oral sex, as well as from mother to baby during pregnancy, known as congenital syphilis. The bacterium responsible, Treponema pallidum, cannot survive long outside the human body, so transmission through objects like toilet seats is extremely rare 1. The disease cannot be spread through casual contact such as hugging, sharing food, or using the same toilet.

Key Transmission Facts

  • Syphilis sores, called chancres, appear at the site where the bacteria entered the body and are highly infectious.
  • Transmission can occur when mucocutaneous syphilitic lesions are present, which is uncommon after the first year of infection 1.
  • Persons exposed sexually to a patient who has syphilis in any stage should be evaluated clinically and serologically, and treated presumptively if necessary, especially if exposure occurred within 90 days preceding the diagnosis of primary, secondary, or early latent syphilis in a sex partner 1.

Prevention and Treatment

  • To prevent transmission, use latex condoms during sexual activity, though they don't completely eliminate risk since sores may occur in areas not covered by condoms.
  • Regular testing is recommended for sexually active individuals, especially those with multiple partners.
  • If diagnosed, syphilis is treated with antibiotics, typically penicillin G benzathine, with dosage and duration varying for later stages.
  • All sexual partners should be notified and tested if syphilis is diagnosed.

From the Research

Syphilis Transmission

  • Syphilis is caused by infection with Treponema pallidum subsp. pallidum, a spiral-shaped bacterium that is usually transmitted by sexual contact with an infected partner 2.
  • The primary and secondary stages of syphilis are the most infectious 2.
  • Syphilis can also be transmitted by an infected pregnant woman to her fetus, resulting in congenital syphilis 2, 3.
  • High-risk sexual activity, migration, and travel, as well as economic and social changes that limit access to healthcare, are host-associated factors that drive the re-emergence and spread of syphilis 2.

Modes of Transmission

  • Sexual contact with an infected partner is the primary mode of syphilis transmission 4, 2.
  • Mother-to-child transmission during pregnancy is another mode of transmission, which can result in congenital syphilis 3.
  • There is no vaccine to prevent syphilis, and diagnosis and treatment of infected individuals and their contacts are key to syphilis control programs 2.

Prevention and Control

  • Preventive therapy is an important element of syphilis control efforts, and a single 1.0-g dose of azithromycin seems to be efficacious for prevention of syphilis in persons exposed to infected sexual partners 4.
  • Sex education and promotion of condom use are also essential to prevent infection 2.
  • Early diagnosis and treatment of syphilis, including screening and treatment of pregnant women, are crucial to reducing the incidence of congenital syphilis 5, 3.

References

Guideline

Guideline Directed Topic Overview

Dr.Oracle Medical Advisory Board & Editors, 2025

Research

Syphilis: Re-emergence of an old foe.

Microbial cell (Graz, Austria), 2016

Research

Increase in incidence of congenital syphilis - United States, 2012-2014.

MMWR. Morbidity and mortality weekly report, 2015

Research

Diagnosis and management of syphilis.

American family physician, 2003

Professional Medical Disclaimer

This information is intended for healthcare professionals. Any medical decision-making should rely on clinical judgment and independently verified information. The content provided herein does not replace professional discretion and should be considered supplementary to established clinical guidelines. Healthcare providers should verify all information against primary literature and current practice standards before application in patient care. Dr.Oracle assumes no liability for clinical decisions based on this content.

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