Congenital syphilis is a serious and potentially life-threatening condition that occurs when a pregnant woman with syphilis transmits the infection to her unborn child. This transmission can lead to severe consequences for the fetus, ranging from mild to severe, and can even result in stillbirth or neonatal death. Understanding the transmission mechanisms, effects, and preventive measures of congenital syphilis is crucial for ensuring the health and well-being of both the mother and the child.¹

Syphilis: an overview

Syphilis is a sexually transmitted infection (STI) caused by the bacterium Treponema pallidum. It is a chronic and systemic disease that can have severe consequences if left untreated. Syphilis is categorized into four stages: primary, secondary, latent, and tertiary.

The primary stage is characterized by the appearance of a painless chancre (sore) at the site of infection, typically on the genitals, rectum, or mouth. The secondary stage is marked by a rash, fever, and other flu-like symptoms. The latent stage is asymptomatic, and the tertiary stage can lead to severe complications affecting various organs, including the brain, cardiovascular system, and bones.²

Transmission from mother to fetus

Transplacental transmission

During pregnancy, the Treponema pallidum bacteria can cross the placental barrier and enter the fetal circulation, leading to fetal infection. This transplacental transmission can occur at any stage of pregnancy, although the risk is highest during the early stages of maternal syphilis.

The risk of transmission is directly proportional to the stage of the maternal infection. In the primary and secondary stages, when the bacterial load is high, the risk of transmission is highest. As the infection progresses to the latent and tertiary stages, the risk of transmission decreases but does not completely disappear.^3,4

Transmission during childbirth

If the mother has an active genital lesion or a high bacterial load during childbirth, the fetus can become infected while passing through the birth canal. This mode of transmission is particularly concerning as it can lead to severe complications for the newborn.⁴

Factors influencing transmission

Several factors can influence the risk of transmission from mother to fetus, including:

• Stage of maternal infection: As mentioned earlier, the risk of transmission is highest during the primary and secondary stages of maternal syphilis
• Duration of maternal infection: The longer the mother has been infected, the higher the risk of transmission, as the bacterial load increases over time
• Maternal treatment: Prompt and adequate treatment of the mother with appropriate antibiotics can significantly reduce the risk of transmission to the fetus
• Gestational age: The risk of transmission is generally higher in the later stages of pregnancy, as the fetus is exposed to the infection for a longer period⁵

Effects of congenital syphilis on the fetus

The effects of congenital syphilis on the fetus can be divided into early and late manifestations, depending on the timing of the infection and the gestational age at the time of transmission.

Early manifestations (occurring within the first two years of life)

• Stillbirth or neonatal death: Congenital syphilis can lead to fetal demise or neonatal death, especially if left untreated
• Low birth weight: Infants with congenital syphilis are often born with low birth weight, which can increase the risk of other complications
• Prematurity: Congenital syphilis can cause premature birth, which can lead to various complications for the newborn
• Congenital syphilitic rash: A characteristic rash, often involving the palms and soles, can be observed in infants with congenital syphilis
• Hepatosplenomegaly: Infants may have an enlarged liver and spleen due to the infection
• Jaundice: Congenital syphilis can cause jaundice (yellowing of the skin and eyes) in newborns
• Mucocutaneous lesions: Skin lesions, such as blisters or ulcers, can occur in infants with congenital syphilis
• Pneumonia: Congenital syphilis can lead to pneumonia in newborns, which can be life-threatening if not promptly treated
• Neurological complications: Infants may experience neurological complications such as meningitis, seizures, or other neurological abnormalities^3,4,6

Late manifestations (occurring after the first two years of life)

• Interstitial keratitis: Inflammation of the cornea, leading to vision problems or blindness
• Deafness: Congenital syphilis can cause hearing loss or deafness in affected individuals
• Dental deformities (Hutchinson's teeth): Characteristic deformities of the permanent teeth, including notched and peg-shaped incisors
• Saddle nose deformity: A characteristic deformity of the nose, where the bridge of the nose appears flattened or saddle-shaped
• Frontal bossing: A prominent forehead, often seen in individuals with congenital syphilis
• Bone deformities: Congenital syphilis can lead to various bone deformities, such as sabre shins (curved shinbones) or other skeletal abnormalities
• Neurological complications: Individuals with congenital syphilis may experience neurological problems, including intellectual disability, seizures, and other neurological manifestations⁶

Prevention and treatment

Early detection and prompt treatment of maternal syphilis are crucial in preventing congenital syphilis and minimizing the adverse effects on the fetus.

Prenatal screening and treatment

Routine screening for syphilis during pregnancy is essential for identifying and treating maternal infections before they can be transmitted to the fetus. The Centers for Disease Control and Prevention (CDC) recommends that all pregnant women should be screened for syphilis at their first prenatal visit and again in the third trimester, or at delivery if they were not screened earlier in pregnancy.

If a pregnant woman tests positive for syphilis, immediate treatment with appropriate antibiotics, typically penicillin, is recommended. Treatment during pregnancy can effectively prevent transmission to the fetus and reduce the risk of adverse outcomes.^1,7

Treatment of congenital syphilis

If congenital syphilis is suspected or confirmed in a newborn, prompt treatment with antibiotics is crucial to prevent long-term complications. The recommended treatment for congenital syphilis is intravenous penicillin or, in cases of penicillin allergy, other suitable antibiotics.⁷

Follow-up care

After treatment, it is essential to monitor the newborn for any signs of relapse or complications. Regular check-ups and follow-up tests may be necessary to ensure the effectiveness of the treatment and to detect any potential long-term effects.

FAQs

Can congenital syphilis be prevented if the mother is treated during pregnancy?

Yes, prompt and adequate treatment of maternal syphilis during pregnancy can significantly reduce the risk of transmission to the fetus and prevent congenital syphilis.

What are the long-term consequences of untreated congenital syphilis?

Untreated congenital syphilis can lead to severe and potentially life-threatening complications, including neurological problems, deafness, blindness, bone deformities, and even death.

Can a baby born with congenital syphilis transmit the infection to others?

No, congenital syphilis is not transmitted from an infected baby to others. The infection occurs only through vertical transmission from the mother to the fetus during pregnancy or childbirth.

How is congenital syphilis diagnosed?

Congenital syphilis is typically diagnosed through a combination of physical examination, laboratory tests (such as blood tests or cerebrospinal fluid analysis), and imaging studies.

Summary

Congenital syphilis is a serious condition that can have severe consequences for the fetus and newborn if left untreated. The transmission of syphilis from mother to fetus can occur through transplacental transmission or during childbirth, with the risk being highest during the early stages of maternal infection.

The effects of congenital syphilis can range from mild to severe, including stillbirth, low birth weight, congenital deformities, and neurological complications. Early detection through routine prenatal screening and prompt treatment of maternal syphilis is crucial in preventing transmission and minimizing adverse effects on the fetus.^1,2

Prevention measures, such as promoting safe sexual practices and increasing awareness about the importance of prenatal care and screening, are essential to reduce the incidence of congenital syphilis. By addressing this issue through a comprehensive approach, we can ensure the health and well-being of both mothers and their children.^5,6