3D Analytics Module Care Intelligence Labcorp


Labcorp offers timely, accurate and convenient screening options that can help curb rising STI rates in the U.S.

supporting image

Syphilis cases on the rise in the United States

  • After a long period of decline in the U.S., syphilis cases continue to rise.1

  • The national rate of primary and secondary syphilis has increased almost every year since 2001. In 2021, 53,767 cases of syphilis were reported, reflecting a 28.6% increase from 2020 to 2021.1

  • Congenital syphilis has similarly increased in prevalence. CDC data showed 2,855 cases of newborn syphilis in 2021 representing a 30.5% increase relative to 2020 and 219.3% increase relative to 2017. Further, in 2012, only three states had over 100 cases of primary and secondary syphilis among women aged 15-44 years; in 2021, 29 states reported over 100 cases.1

Screening patients for syphilis

Per the CDC-recommended algorithm, initial testing is done with a treponemal assay (EIA or CIA) followed by a quantitative nontreponemal test for confirmation (quantitative RPR or other nontreponemal test). Discordant samples are resolved on the basis of a TPPA assay.

All positive nontreponemal tests must be quantified at time of treatment, as titers are used to monitor treatment success.2

Testing recommendations per the CDC


Women and men who have sex with women

Screen asymptomatic adults at increased risk (i.e., history of incarceration or transactional sex work, geography, race/ethnicity and being a male younger than 29 years) for syphilis infection.3

Pregnant women

  • All pregnant women at the first prenatal visit
  • Retest at 28 weeks’ gestation and at delivery if at high risk. High-risk individuals include those who live in a community with high syphilis morbidity or is at risk for syphilis acquisition during pregnancy, uses drugs or has STIs during pregnancy. High-risk individuals also include those with multiple sexual partners, a new partner or a partner with STIs)

Men who have sex with men (MSM)

  • At least annually for sexually active MSM3
  • Every 3 to 6 months if at increased risk3

Transgender and gender diverse people

Consider screening at least annually based on reported sexual behaviors and exposure3

Did you know…

States such as Texas and Washington are making new recommendations in testing for syphilis and congenital syphilis. Several states have had some success at curbing rising syphilis rates and outbreaks in recent years.

Syphilis screening made simple

On December 20, 2021, CDC published a letter acknowledging the FDA alert of the potential for false positives of RPR results and reminding the healthcare community of the importance of confirming reactive RPR results with treponemal antibody testing.3 False-reactive RPR test results have historically been observed in individuals with autoimmune disorders, systemic infections unrelated to syphilis, (e.g., tuberculosis, rickettsial diseases, HIV, and endocarditis) as well as following immunization (particularly for smallpox) and during pregnancy.4

The CDC-recommended algorithms for the screening and diagnosis of syphilis include both treponemal and non-treponemal assays. Labcorp offers both the Reverse syphilis screening algorithm and the traditional syphilis screening algorithm.


* Please note, CDC does not recommend one algorithm over the other.


  1. Centers for Disease Control and Prevention. National Overview of STDs, 2021. Cdc.gov. Updated April 11, 2023. Accessed May 9, 2023. https://www.cdc.gov/std/statistics/2021/overview.htm#Syphilis
  2. U.S. Department of Health and Human Services Centers for Disease Control and Prevention Syphilis Pocket Guide for Providers. Accessed September 20, 2021.
  3. Sexually Transmitted Infections Treatment Guidelines, 2021.https://www.cdc.gov/std/treatment-guidelines/default.htm. Accessed July 29, 2021.
  4. Centers for Disease Control and Prevention (CDC). Partners in Prevention letter. CDC website.https://www.cdc.gov/std/fda-alert-12-20-2021.pdf. December 20, 2021. Accessed March 2022.