With congenital syphilis at a 30-year high in the US, experts stress that early and universal syphilis screening in pregnancy is vital to protect both mothers and newborns from preventable harm.
Study: Screening for Syphilis Infection During Pregnancy: US Preventive Services Task Force Reaffirmation Recommendation Statement. Image Credit: Summit Art Creations / Shutterstock.com
In a recent public statement, the United States Preventive Services Task Force (USPSTF) re-evaluated available evidence and reaffirmed its 2018 recommendation on syphilis screening in pregnancy.
Congenital syphilis in the US
In 2023, 3,882 babies were born with congenital syphilis in the U.S., which is the highest rate reported in 30 years. Researchers estimate that 90% of these cases were preventable by timely diagnosis and treatment of the mother.
Of infants born with congenital syphilis in 2023, 279 died in the womb or during or after delivery. Congenital syphilis increases the risk of premature birth, low birth weight, bony deformities, anemia, liver and spleen enlargement, blindness or hearing loss, and meningitis.
The number of congenital syphilis cases for every 100,000 live births was highest among Native American and Alaska Native women at 680, followed by 296, 222, and 125 among Native Hawaiian/Pacific Islander Women, Black, and Latina/Hispanic women, respectively.
Among White women, 57.3 cases of congenital syphilis cases were reported for every 100,000 live births, whereas 82 and nine were reported among multiracial and Asian women, respectively. Socioeconomic disparities, as well as cultural and demographic factors, contribute to these differences in the prevalence of syphilis in women.
USPSTF recommendation
In 2018, the USPSTF issued an A recommendation for syphilis screening during pregnancy. Recently, this organization performed a reaffirmation process to determine whether current evidence supports a high net benefit for syphilis screening with high certainty.
Early pregnancy screening for syphilis is recommended for all pregnant women, irrespective of risk or earlier screening status. The earlier syphilis is treated, the greater the reduction in the risk of adverse pregnancy outcomes; however, late treatment can also prevent congenital syphilis.
Screening tests
Screening tests for syphilis include the Treponema. pallidum particle agglutination (TP-PA) test, which identifies antibodies against T. pallidum, the pathogen that causes syphilis. Non-treponemal tests like the Venereal Disease Research Laboratory (VDRL) test or the rapid plasma reagin (RPR) test can also be used to diagnose syphilis.
Non-treponemal tests detect antibodies to lipoidal antigens released from damaged tissues and may be non-specific. As a result, a positive VDRL must be confirmed in the second step by a confirmatory test like TP-PA.
Another screening sequence begins with automated treponemal testing, such as enzyme-linked or chemiluminescence immunoassay. In the event that any test results do not agree, a second confirmatory treponemal test, preferably TP-PA, is performed.
Point-of-care (POC) tests are available to measure anti-T. pallidum antibodies; however, these tests have not been fully validated.
The USPSTF recommends early, universal screening for syphilis infection during pregnancy; if an individual is not screened early in pregnancy, the USPSTF recommends screening at the first available opportunity.”
Treating syphilis in pregnancy
The U.S. Centers for Disease Control and Prevention (CDC) recommends that syphilis in pregnancy be treated with a penicillin G injection. In the event that a woman has a penicillin allergy, which is reported in 10% of patients, she should be desensitized to this reaction and treated with the drug. An ultrasound evaluation of the fetus is required if syphilis is identified in the second half of pregnancy.
Some acute adverse effects of this treatment may include immediate penicillin-induced allergic reactions and the Jarisch-Herxheimer reaction, which is characterized by an acute fever accompanied by a rash, body aches, tachycardia, or low blood pressure within 24 hours of antibiotic treatment of spirochaete infection. These adverse events affect 5% and 2.5% of patients, respectively.
Among patients at high risk of penicillin allergy, the rate of adverse effects is 27%, even after oral desensitization, compared to 2.5% after intravenous desensitization.
Rescreening for syphilis
An initial negative early pregnancy screening for syphillis is followed by diagnosing congenital syphilis iduringn late pregnancy in 5% of cases, 41%, 28%, and 20% of whom are Black, Hispanic/Latina, and White women, respectively.
Many organizations, including the CDC, Women’s Preventive Services Initiative (WPSI), and the American Academy of Pediatrics (AAP), recommend rescreening high-risk pregnant women at about 28 weeks and at delivery. These include those living in localities with a high prevalence of the infection, in prison, infected with the human immunodeficiency virus (HIV), or with more than one sexual partner.
Conversely, the American College of Obstetricians and Gynecologists (ACOG) recommends rescreening all pregnant women for syphilis.
The USPSTF cites insufficient evidence to recommend rescreening, thus necessitating additional research on its effectiveness. Clinicians should be aware of local syphilis prevalence and state-specific screening laws, which vary in their requirements for universal rescreening.
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