Congenital Syphilis Still a Public Health Concern

Bonnie M. Word, MD


October 24, 2022

Bonnie M. Word, MD

You’re rounding in the nursery and informed of the following about one of your new patients: He’s a 38-week-old infant delivered to a mother diagnosed with syphilis at 12 weeks’ gestation at her initial prenatal visit. Her rapid plasma reagin (RPR) was 1:64 and the fluorescent treponemal antibody–absorption (FTA-ABS) test was positive. By report she was appropriately treated. Maternal RPRs obtained at 18 and 28 weeks’ gestation were 1:16 and 1:4, respectively. Maternal RPR at delivery and the infant’s RPR obtained shortly after birth were both 1:4. The mother wants to know if her baby is infected.

One result of syphilis during pregnancy is intrauterine infection and resultant congenital disease in the infant. Before you answer this mother, let’s discuss syphilis.

Congenital syphilis is a significant public health problem. In 2021, there were a total of 2,677 cases reported for a rate of 74.1 per 100,000 live births. Between 2020 and 2021, the number of cases of congenital syphilis increased 24.1% (2,158-2,677 cases), concurrent with a 45.8% increase (10.7-15.6 per 100,000) in the rate of primary and secondary syphilis in women aged 15-44 years. Between 2012 and 2021, the number of cases of congenital syphilis increased 701.5% (334-2,677 cases) and the increase in rates of primary and secondary syphilis in women aged 15-44 was 642.9% over the same period.

Source: CDC

Why are the rates of congenital syphilis increasing? Most cases result from a lack of prenatal care and thus no testing for syphilis. The next most common cause is inadequate maternal treatment.

Congenital syphilis usually is acquired through transplacental transmission of spirochetes in the maternal bloodstream. Occasionally, it occurs at delivery via direct contact with maternal lesions. It is not transmitted in breast milk. Transmission of syphilis:

  • Can occur any time during pregnancy.

  • Is more likely to occur in women with untreated primary or secondary disease (60%-100%).

  • Is approximately 40% in those with early latent syphilis and less than 8% in mothers with late latent syphilis.

  • Is higher in women coinfected with HIV since they more frequently receive no prenatal care and their disease is inadequately treated.

Coinfection with syphilis may also increase the rate of mother-to-child transmission of HIV.

Untreated early syphilis during pregnancy results in spontaneous abortion, stillbirth, or perinatal death in up to 40% of cases. Infected newborns with early congenital syphilis can be asymptomatic or have evidence of hepatosplenomegaly, generalized lymphadenopathy, nasal discharge that is occasionally bloody, rash, and skeletal abnormalities (osteochondritis and periostitis). Other manifestations include edema, hemolytic anemia, jaundice, pneumonia, pseudoparalysis, and thrombocytopenia. Asymptomatic infants may have abnormal cerebrospinal fluid findings including elevated CSF white cell count, elevated protein, and a reactive venereal disease research laboratory test.

Late congenital syphilis, defined as the onset of symptoms after 2 years of age is secondary to scarring or persistent inflammation and gumma formation in a variety of tissues. It occurs in up to 40% of cases of untreated maternal disease. Most cases can be prevented by maternal treatment and treatment of the infant within the first 3 months of life. Common clinical manifestations include interstitial keratitis, sensorineural hearing loss, frontal bossing, saddle nose, Hutchinson teeth, mulberry molars, perforation of the hard palate, anterior bowing of the tibia (saber shins), and other skeletal abnormalities.

Diagnostic tests. Maternal diagnosis is dependent upon knowing the results of both a nontreponemal (RPR, VDRL) and a confirmatory treponemal test (TP-PA, TP-EIA, TP-CIA, FTA-ABS,) before or at delivery. TP-PA is the preferred test. When maternal disease is confirmed, the newborn should have the same quantitative nontreponemal test as the mother. A confirmatory treponemal test is not required

Evaluation and treatment. It’s imperative that children born to mothers with a reactive test, regardless of their treatment status, have a thorough exam performed before hospital discharge. The provider must determine what additional interventions should be performed.

The American Academy of Pediatrics and the Centers for Disease Control and Prevention ( have developed standard algorithms for the diagnostic approach and treatment of infants born to mothers with reactive serologic tests for syphilis. It is available in the Red Book for AAP members ( Recommendations based on various scenarios for neonates up to 1 month of age include proven or highly probable congenital syphilis, possible congenital syphilis, congenital syphilis less likely, and congenital syphilis unlikely. It is beyond the scope of this article to list the criteria and evaluation for each scenario. The reader is referred to the algorithm.

If syphilis is suspected in infants or children older than 1 month, the challenge is to determine if it is untreated congenital syphilis or acquired syphilis. Maternal syphilis status should be determined. Evaluation for congenital syphilis in this age group includes CSF analysis for VDRL, cell count and protein, CBC with differential and platelets, hepatic panel, abdominal ultrasound, long-bone radiographs, chest radiograph, neuroimaging, auditory brain stem response, and HIV testing.

Let’s go back to your patient. The mother was diagnosed with syphilis during pregnancy. You confirm that she was treated with benzathine penicillin G, and the course was completed at least 4 weeks before delivery. Treatment with any other drug during pregnancy is not appropriate. The RPR has declined, and the infant’s titer is equal to or less than four times the maternal titer. The exam is significant for generalized adenopathy and slightly bloody nasal discharge. This infant has two findings consistent with congenital syphilis regardless of RPR titer or treatment status. This places him in the proven or highly probable congenital syphilis group. Management includes CSF analysis (VDRL, cell count, and protein), CBC with differential and platelet count, and treatment with penicillin G for 10 days. Additional tests as clinically indicated include: long-bone radiograph, chest radiography, aspartate aminotranferase and alanine aminotransferase levels, neuroimaging, ophthalmologic exam, and auditory brain stem response. Despite maternal treatment, this newborn has congenital syphilis. The same nontreponemal test should be obtained every 2-3 months until it is nonreactive. It should be nonreactive by 6 months. If the infection persists to 6-12 months post treatment, reevaluation including CSF analysis and retreatment may be indicated.

Congenital syphilis can be prevented by maternal screening, diagnosis, and treatment. When that fails it is up to us to diagnosis and adequately treat our patients.

Dr. Word is a pediatric infectious disease specialist and director of the Houston Travel Medicine Clinic. She said she had no relevant financial disclosures. Email her at

This article originally appeared on, part of the Medscape Professional Network.

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