Incidence and outcomes of jarisch-herxheimer reactions following treatment for infectious syphilis in late pregnancy in Alberta, Canada, 2015-2020

Macumber, S.; Singh, A.; Robinson, J.; Smyczek, P.; Sklar, C.; Gratrix, J.; Rathjen, L.

Background In Alberta (Canada), infectious syphilis rose from 4:100,000 in 2014 to 52:100,000 in 2019 with a parallel rise in congenital syphilis. Treatment of pregnant women is highly efficacious but can precipitate the Jarisch-Herxheimer (JH) reaction. Symptoms of JH reaction are often transient but may include fever, uterine contractions, fetal heart rate abnormalities, and preterm labor. Because of these observations, many guidelines recommend hospitalization for fetal monitoring be considered. We sought to determine the incidence, and severity of JH reactions and the maternal and fetal outcomes following treatment. Methods Retrospective cohort study of pregnant women at >20 weeks gestation admitted to urban referral centers for treatment of infectious syphilis between 2015 and 2020. Data was extracted from a provincial database and supplemented by a review of medical records. Data collection was completed in March 2021. Results 39 women received benzathine penicillin G for the treatment of infectious syphilis in pregnancy. One mild JH reaction was identified in a patient with early latent syphilis. There were no serious maternal or fetal outcomes attributable to treatment. Average gestational age at treatment and delivery was 26 and 37 weeks respectively. Ten cases were staged as primary, 4 as secondary, and 25 as early latent syphilis. Five cases of confirmed congenital syphilis were identified. Further analysis of results is underway. Conclusions Data from our study challenges the recommendation for routine admission for the treatment of infectious syphilis in late pregnancy as no moderate or severe JH reactions were identified in our cohort. Further research is required to determine if a subgroup of women not identified in our cohort are at risk for moderate or severe JH reaction. These findings are timely given the global resurgence of infectious syphilis as inpatient resources continue to be strained by the ongoing COVID-19 pandemic..