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.
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.