Exploring changes in maternal and congenital syphilis epidemiology to identify factors contributing to increases in congenital syphilis in Florida: a two time-period observational study (2013–2014 vs 2018–2019)

OBJECTIVES: As, cases of congenital syphilis (CS) and infectious syphilis among women more than doubled in Florida and across the nation during 2013–2019, we sought to understand what may be contributing to these increases in Florida. DESIGN: A two time-period observational study. SETTING: Pregnant women with reported syphilis infections and their pregnancy outcomes (2013–2014 and 2018–2019) in Florida. PARTICIPANTS: 1213 pregnant women with reported syphilis infections living in Florida and 341 infants meeting the CS case definition. OUTCOME MEASURES: We assessed what proportion of the increase in CS was from increases in maternal syphilis infections. We examined maternal demographics, infection characteristics and timing of diagnoses that could explain the increase in CS. Finally, we reviewed if changes in presentation or severity of CS cases occurred. RESULTS: During 2013–2014, 83 (21%) of 404 pregnant women with syphilis delivered babies with CS. During 2018–2019, 258 (32%) of 809 pregnant women with syphilis delivered babies with CS. Comparing CS prevention rates, it was determined that 65% of the increase in CS was due to the increases in maternal syphilis infections. The proportion of maternal cases staged as primary or secondary increased over time (7%–13%) (p<0.01) and reports of drug use became slightly more common (6%–10%) (p=0.02). During 2018–2019, women delivering CS infants were more likely to be reinfected during the same pregnancy (27 (10%) vs 5 (6%) p=0.23) and more had negative third trimester screening tests (43 (17%) vs 7 (8% p=0.07)). The percentage of infants with CS who had ≥1 sign or symptom increased from 35% to 40%, and the combined total of stillbirths and infant deaths increased from 5 to 26. CONCLUSIONS: Recently, more pregnant women are being infected with syphilis and a higher per cent are not being treated to prevent CS. The reasons for this finding are unclear.