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Congenital syphilis (CS)

Last reviewed dd mmm yyyy. Last edited dd mmm yyyy

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The question of congenital syphilis may be raised during pregnancy if:

  • ante-natal serology is positive
  • there is intra-uterine growth retardation
  • there is premature labour

In the newborn, congenital syphilis becomes apparent between the 2nd and 6th weeks after birth

Congenital syphilis (CS)

  • vertical transmission of syphilis during pregnancy (trans-placental passage) can occur during any trimester and at any stage of infection - with the highest risk of transmission in primary syphilis

  • risk of adverse pregnancy outcomes, including intrauterine fetal demise (IUFD), prematurity and neonatal death, is considerably higher in women with untreated syphilis than in pregnant women with no syphilis or in pregnant women who receive adequate treatment for syphilis following diagnosis at first trimester screening (1)

  • there is evidence that the risk of congenital syphilis (CS) is higher in women who become infected with syphilis during pregnancy than in women who have active syphilis at the time of conception (2,3). However, the probability of CS and other adverse pregnancy outcomes is difficult to measure and to quantify, in part, due to the very small number of CS cases

In infants born with CS, the infection can cause reduced growth and development, and result in neurological impairment, bone deformities and hearing loss (3,4)

  • benzyl penicillin sodium (intravenous) is used to treat CS in neonates. Treatment is given for ten days with 30 mg/kg doses given 12-hourly for the first seven days and 8-hourly for the subsequent three days (1,5)

  • infants are likely to then have monitoring beyond the completion of treatment. Infants treated in the first two months of life have a good short-term prognosis, but the long-term prognosis for infants treated for CS at birth or treated later, due to delayed diagnosis, have not been reported (6,7)

  • evidence indicates that most infants with CS develop signs by 5 weeks, however, there is a lack of data on the proportion of CS cases with late presentation (after 2 years) (1)

In the UK, the number of CS cases in recent years has remained low and is below the WHO threshold for elimination (<0.5/1000 live births)

  • in the 5-year period Feb 2010 – Jan 2015, there were 17 confirmed cases of CS (8,9)
  • where information on syphilis stage was available, 60% of CS cases were born to women with primary syphilis, 30% secondary syphilis and 10% early latent syphilis
  • of the 20 CS cases between February 2010 and January 2017, 11 had no record of the mother receiving antenatal screening (9)

There is a chance that women who screen negative for syphilis become positive later in pregnancy, either because they become infected during the pregnancy, or because their infection was too recent for a detectable antibody response to have been mounted at the time of the first screen. In March 2016 - January 2017 four cases of CS occurred in women who received a negative result when screened for syphilis in pregnancy – although the timing of the screening in pregnancy was not reported. None of these women had a repeat screen during pregnancy.

Confirmatory testing later showed that they had acquired syphilis during pregnancy. In these four cases, two women had infants with confirmed CS and two had infants classified as probable CS cases (9).

Syphilis screening assay

  • blood samples are initially tested using an enzyme immunoassay (EIA)
    • assay tests for antibodies against treponemal infections, including, but not exclusively, syphilis (Treponema pallidum)
    • samples from women with a non-syphilis treponemal infection will initially produce a positive result as will women with a previous syphilis infection
    • syphilis serology can remain positive for many years after acute infection with or without treatment
    • following a positive result, the same test is repeated using the same assay, and then a T. pallidum particle agglutination assay (TPPA) is performed on the same specimen to confirm the result



  • 1) Sheffield JS, Sánchez PJ, Morris G, et al. Congenital syphilis after maternal treatment for syphilis during pregnancy. Am J Obstet Gynecol 2002;186:569–73. doi:10.1067/mob.2002.121541
  • 2) Ricci JM, Fojaco RM, O’Sullivan MJ. Congenital syphilis: the University of Miami/Jackson Memorial Medical Center experience, 1986-1988. Obstet Gynecol 1989;74:687–93.
  • 3)Gomez GB, Kamb ML, Newman LM, et al. Untreated maternal syphilis and adverse outcomes of pregnancy: a systematic review and meta-analysis. Bull World Health Organ 2013;91:217–26. doi:10.2471/BLT.12.107623
  • 4)De Santis M, De Luca C, Mappa I, et al. Syphilis Infection during Pregnancy: Fetal Risks and Clinical Management. Infect Dis Obstet Gynecol 2012;2012. doi:10.1155/2012/430585
  • 5) Kingston M, French P, Fifer H, et al. Congenital syphilis in England and amendments to the BASHH guideline for management of affected infants. Int J STD AIDS 2017;28:1361–2. doi:10.1177/0956462417733866
  • 6) Arnold SR, Ford-Jones EL. Congenital syphilis: A guide to diagnosis and management. Paediatr Child Health 2000;5:463–9.
  • 7) Mwaniki MK, Atieno M, Lawn JE, et al. Long-term neurodevelopmental outcomes after intrauterine and neonatal insults: a systematic review. Lancet 2012;379:445–52. doi:10.1016/S0140-6736(11)61577-8
  • 8)Simms I, Tookey PA, Goh BT, et al. The incidence of congenital syphilis in the United Kingdom: February 2010 to January 2015. BJOG Int J Obstet Gynaecol 2017;124:72–7. doi:10.1111/1471-0528.13950
  • 9) Furegato M, Fifer H, Mohammed H, et al. Factors associated with four atypical cases of congenital syphilis in England, 2016 to 2017: an ecological analysis. Euro Surveill Bull Eur Sur Mal Transm Eur Commun Dis Bull 2017;22. doi:10.2807/1560-7917.ES.2017.22.49.17-00750

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