Congenital syphilis is an infection caused by the bacterium Treponema pallidum, passed from a mother to her baby during pregnancy or at birth. If the mother’s infection is not identified and treated, this condition can result in severe health complications for the developing fetus. Since syphilis is a preventable and curable sexually transmitted infection, the occurrence of congenital syphilis is considered a significant public health concern. Timely prenatal diagnosis and intervention are necessary to prevent adverse outcomes for the newborn.
How the Infection is Transmitted to the Fetus
Transmission of Treponema pallidum from the mother to the fetus occurs primarily through the placental barrier. This biological process allows the bacteria to enter the fetal bloodstream directly from the maternal circulation. Although transmission can occur at any point during gestation, the overall risk increases significantly after the first trimester.
The likelihood of transmission depends heavily on the stage of the mother’s untreated infection. For mothers with primary or secondary syphilis, the risk of transmission can be as high as 60% to 100%. For those with latent or tertiary syphilis, the rate is lower, falling between 7% and 40% of cases. This variability highlights that the mother’s stage of infection is a major determinant of the severity of fetal consequences.
Immediate and Early Effects on the Newborn
The consequences of congenital syphilis range from severe adverse pregnancy outcomes to signs that emerge months after birth. Untreated syphilis in pregnancy significantly elevates the risk of life-threatening events, including miscarriage, stillbirth, and neonatal death shortly after delivery. Surviving infants may be born prematurely or with a low birth weight.
Many infected infants are born without noticeable signs or symptoms, which can complicate the initial diagnosis. If the disease manifests in the first two years of life, it is classified as early congenital syphilis. Common early symptoms include characteristic skin rashes, often appearing on the palms of the hands and soles of the feet, and a persistent, runny nasal discharge known as “snuffles.”
The infection commonly affects the internal organs and skeletal structure of the newborn. Early signs frequently include hepatosplenomegaly, the abnormal enlargement of both the liver and the spleen. The infection can also cause bone abnormalities like osteochondritis, an inflammation of the bone and cartilage, which may lead to pain and pseudoparalysis. In severe cases, central nervous system involvement can lead to neurological conditions such as meningitis, seizures, or developmental delays.
Medical Treatment and Long-Term Prognosis
Diagnosis of congenital syphilis is based on the mother’s history, a physical examination of the baby, and laboratory tests. Diagnostic testing involves blood tests for specific antibodies, analysis of cerebrospinal fluid, and X-rays for characteristic bone changes. Because passive transfer of maternal antibodies can cause a positive result in the baby, diagnosis often focuses on the mother’s treatment status and specific findings in the infant.
The standard and only effective treatment for both the pregnant mother and the newborn is penicillin. The specific protocol for the baby depends on the extent of the infection and clinical findings, such such as an abnormal cerebrospinal fluid analysis. Treatment generally involves a 10-day course of intravenous penicillin G, though some low-risk cases may require only a single intramuscular injection.
If the infection is diagnosed and treated early, the prognosis is favorable, and the baby can be completely cured. Delayed or inadequate treatment risks long-term, irreversible complications known as late congenital syphilis, appearing after two years of age. These late effects can include:
- Sensorineural hearing loss.
- Vision problems such as interstitial keratitis.
- Permanent bone deformities.
- Intellectual disability and neurological damage from neurosyphilis.
Preventing Congenital Syphilis Through Prenatal Care
Prevention of congenital syphilis relies almost entirely on the consistent and timely screening and treatment of pregnant women. Routine prenatal screening is recommended at the initial prenatal care visit, ideally during the first trimester, as a fundamental step in identifying the infection early.
Repeat screening is advised in the third trimester and at delivery for women in high-rate areas or those with specific risk factors. This repeated testing is necessary because a woman who tests negative early in pregnancy could still acquire the infection later on. If the mother is diagnosed, prompt treatment with penicillin is essential. Treatment completed at least 30 days before delivery can prevent transmission to the baby in most cases.