Congenital Syphilis in England: A Decade of Preventable Stillbirths and Missed Diagnoses

Congenital syphilis, a disease that should have vanished from a wealthy country with near-universal antenatal screening, is quietly leaving a trail of stillbirths, neonatal deaths and delayed diagnoses across England. A comprehensive national surveillance study, covering every reported case between January 2015 and June 2024, has now laid bare the scale of the problem and the sobering gaps in clinical practice that allowed it to happen. The findings, published in The Lancet Regional Health – Europe, come from the Integrated Screening Outcomes Surveillance Service (ISOSS), which operates within NHS England’s Infectious Diseases in Pregnancy Screening Programme, and they carry an uncomfortable message: even where screening coverage reaches 99.8 per cent, preventable transmission continues.

The research team, led by Helen Fifer and Helen Peters with colleagues from sexual health, paediatric infectious diseases and pathology services across the United Kingdom, reviewed 79 reported cases through a multidisciplinary Clinical Expert Review Panel. Using strict clinical-pathological criteria, the panel classified 67 infants as confirmed or probable cases of congenital syphilis. These infants were born to 65 women, including two sets of twins. The outcomes were stark: 54 were liveborn, of whom five died within the first month of life, and 13 were stillborn. Over half of the liveborn infants — 37 of 67 — arrived preterm, and half weighed less than 2.5 kilograms at birth. Against a background of roughly 4.96 million live births in England during the study period, the absolute numbers are small, with an incidence of 0.023 per 1,000 live births still below the World Health Organization elimination threshold of 0.5 per 1,000. But each case represents a failure of a system designed to prevent exactly this outcome.

The epidemiological backdrop explains much of the rise. England recorded 9,535 cases of early infectious syphilis in 2024, the highest annual figure since the 1940s. Although most infections occur among gay and bisexual men, diagnoses in women tripled between 2015 and 2024, climbing from 273 to 830. This resurgence in adults of reproductive age inevitably feeds into pregnancy. Yet in 1999, researchers had proposed removing syphilis from the antenatal screening panel altogether because congenital cases had all but disappeared. The new data show how quickly that calculus changed: since 2019, an average of ten congenital cases per year have been reported, compared with just one or two per year in the early 2010s.

Perhaps the most striking finding is that nearly half of the affected infants — 30 of 65 pregnancies ending in congenital syphilis — were born to mothers who screened negative for syphilis at their first antenatal appointment and then acquired the infection later in pregnancy. Because England offers only a single universal screen at booking, supplemented by risk-based repeat testing, these women were never re-tested. The risk-based strategy depends on women disclosing new sexual partners, partner sexually transmitted infection diagnoses, drug injection, or sex work, and on clinicians recognising and acting on those disclosures. Many of the mothers in this study had no identifiable risk factors at all and would only have been caught by a universal repeat screen later in gestation, as is practised in higher-prevalence regions of the United States and Europe.

Diagnostic delays compounded the harm. Clinicians repeatedly reported being falsely reassured by a negative antenatal screening result. Infants born to these mothers often arrived at or shortly after birth with non-specific, multisystem illness — irritability, respiratory compromise, thrombocytopaenia, jaundice — that was frequently mistaken for presumed neonatal sepsis. Yet almost all affected infants showed additional features uncommon in sepsis: hepatosplenomegaly, rash or skin and mucosal lesions, desquamation, and abnormalities of the long bones. In one neonatal death, an infant with respiratory symptoms, thrombocytopaenia and anaemia was never tested for syphilis during life; the diagnosis emerged only at postmortem. Several children with persistent symptoms were not tested for months or years, with some cases identified only between 12 and 24 months of age, sometimes incidentally when the mother was screened during a subsequent pregnancy.

Even among infants whose mothers were diagnosed antenatally or in labour, clinical recognition proved challenging. Of 28 such livebirths, eight infants had no symptoms at birth, and the most common signs among symptomatic babies were hepatosplenomegaly in 11, rash or mucocutaneous lesions in seven, and bone abnormalities in five, typically accompanied by thrombocytopaenia, anaemia or jaundice. More unusual complications included hydrops in four infants, hydrocephalus and nephrotic syndrome in two each, and meningitis in one. The authors note that syphilis has long been called ‘the great imitator’, and the study confirms that congenital disease lives up to the name. They endorse proposals to broaden the traditional ‘TORCH’ screen for suspected congenital infection — toxoplasmosis, rubella, cytomegalovirus and herpes simplex — to a ‘SCORTCH’ panel that explicitly includes syphilis, alongside chickenpox and blood-borne viruses.

The study also exposes weaknesses in laboratory diagnosis. Serology in newborns is inherently difficult because maternal IgG antibodies cross the placenta, and a non-treponemal titre four times higher than the mother’s is considered diagnostic — yet only 24 per cent of the 41 mother–infant pairs with comparable results met that threshold, rising to 50 per cent among infants whose mothers acquired syphilis after a negative booking screen, presumably because those mothers went untreated. By contrast, treponemal IgM, which does not cross the placenta, was positive in 86 per cent of the 35 infants tested. Polymerase chain reaction (PCR) testing for Treponema pallidum DNA proved a highly useful adjunct, with positive results from nasal and throat swabs, skin lesions, blood, cerebrospinal fluid, placenta and even bone biopsy, and all four stillbirths with PCR results testing positive. Yet fewer than a quarter of liveborn infants had any specimen sent for PCR, a gap the UK Health Security Agency is now addressing by providing free PCR testing to all UK laboratories.

Behind the clinical statistics lies a darker pattern of social vulnerability. Just over half of the women — 34 of 65 — had at least one complex social factor documented during pregnancy, and most of those experienced multiple overlapping disadvantages. These included involvement with social services in 25 cases, insecure housing in 19, mental health problems in 14, difficulties engaging with healthcare in 14, drug or alcohol misuse in 12, intimate partner violence in nine, and sex work in six. Many women booked late for antenatal care, after 12 weeks, or not at all, and treatment completed too close to delivery to cure the fetus. For cure to succeed, penicillin therapy must finish at least four weeks before birth, so late booking combined with preterm delivery leaves an impossibly narrow window. Several mothers were also treated with macrolide antibiotics, a regimen now known to fail frequently because of widespread macrolide resistance in syphilis strains; UK guidelines were amended in 2019 to remove this option and now explicitly advise against it.

The authors are careful to acknowledge the limitations of their work. Prospective surveillance only began in 2020, with data for 2015 to 2020 collected retrospectively, so early cases were probably undercounted. Reporting was voluntary until April 2025, when congenital syphilis became a notifiable disease in England. The cases captured are also likely skewed towards the severe end of the spectrum, and an unknown number of asymptomatic infants may remain undiagnosed, carrying a risk of late congenital syphilis with its devastating effects on bones, teeth, eyes and the nervous system. International comparisons suggest the problem is not unique to England: series from the United States, Argentina and Western Australia describe similar patterns of asymptomatic birth followed by early symptom onset, and diagnostic difficulty.

The message for policymakers is clear. The UK National Screening Committee, which concluded in 2019 that universal repeat screening at 28 weeks would not be cost-effective, is reviewing that position, and the new data suggest many cases would have been caught by such a policy. Alongside repeat screening, the authors call for greater awareness among clinicians that a negative early screen offers no protection for the rest of pregnancy, improved recognition of maternal symptoms such as vulval lesions and rashes, wider use of PCR and IgM testing, and closer collaboration with inclusion health services — housing, drug treatment and outreach teams — to reach socially excluded women. With the World Health Organization targeting triple elimination of syphilis, HIV and hepatitis B transmission by 2030, England’s decade of surveillance data serves as a reminder that elimination is not achieved by screening programmes alone, but by the clinical vigilance, timely treatment and social support that make those programmes work.

Subject of Research: Congenital syphilis transmission, clinical presentation and diagnostic challenges in England, 2015–2024

Article Title: Clinical characteristics and factors contributing to transmission of congenital syphilis in England, 2015–24: a national surveillance study

Article References: Fifer, H., Peters, H., Kingston, M., Francis, K., Till, R., Thorne, C., Lyall, H., Dermont, S., Cohen, M. C., Sultan, B., Oomeer, S., Bamford, A., Hoodbhoy, S., Permalloo, N., Dickins, D., Emonts, M., Jones, C. E., Andrews, S., & Elbech, A. (2026). Clinical characteristics and factors contributing to transmission of congenital syphilis in England, 2015–24: a national surveillance study. The Lancet Regional Health – Europe, 70, Article 101864. https://doi.org/10.1016/j.lanepe.2026.101864

Image Credits: AI Generated

DOI: 10.1016/j.lanepe.2026.101864

Keywords: congenital syphilis, antenatal screening, Treponema pallidum, stillbirth, neonatal death, vertical transmission, PCR diagnostics, pregnancy, public health surveillance, England, social vulnerability, Lancet Regional Health Europe