If my partner has been diagnosed with syphilis, is a 1:1 ratio of syphilis an indicator that they contracted it from me?

A 1:1 Ratio in Syphilis Testing Does Not Indicate Source of Infection

A 1:1 ratio in syphilis testing is not an indicator that your partner contracted the infection from you. 1, 2 Syphilis test results cannot determine the source or timing of infection between partners.

Understanding Syphilis Testing and Interpretation

• Syphilis diagnosis requires both treponemal and nontreponemal tests, as using only one type is insufficient for accurate diagnosis 2
• Nontreponemal tests (like VDRL or RPR) are reported as titers (ratios) and correlate with disease activity 2
• A "1:1 ratio" likely refers to the lowest positive dilution in a nontreponemal test, which simply indicates a positive result 2
• Titer levels can vary based on multiple factors including stage of infection, prior treatment, and individual immune response 2

Why Test Results Cannot Determine Transmission Direction

• Serologic tests can only confirm infection but cannot determine:

  • Who infected whom 1
  • The exact timing of infection 1, 2
  • The source of the infection 2

• Titers in early syphilis can range widely and do not correlate with how recently the infection was acquired 2

Partner Management Recommendations

• The Centers for Disease Control and Prevention recommends presumptive treatment for sexual partners of patients with syphilis who were exposed within 90 days prior to diagnosis, even if they are seronegative 1
• For primary syphilis, partners from the 3 months plus duration of symptoms before treatment should be identified and evaluated 1
• For secondary syphilis, partners from the 6 months plus duration of symptoms before treatment should be identified and evaluated 1
• For early latent syphilis, partners from 1 year before treatment should be identified and evaluated 1

Important Considerations

• Both partners should be tested for HIV, as co-infection is common 1, 2
• Treatment with benzathine penicillin G 2.4 million units IM in a single dose is recommended for early syphilis 1, 2
• Follow-up testing is essential to ensure adequate treatment response, with nontreponemal titers expected to decline fourfold within 6 months after treatment of primary or secondary syphilis 2, 3

Common Pitfalls to Avoid

• Assuming test results can determine who infected whom - this is a common misconception 1
• Delaying treatment while trying to determine the source of infection - early treatment prevents progression to later stages with significant morbidity and mortality 1
• Overlooking the need for partner notification and treatment regardless of who was infected first 1

Remember that the focus should be on ensuring both you and your partner receive appropriate treatment rather than determining the source of infection, as this cannot be determined from test results alone.