Increase in Incidence of Congenital Syphilis — United States, 2012–2014

Virginia Bowen, PhD; John Su, MD, PhD; Elizabeth Torrone, PhD; Sarah Kidd, MD; Hillard Weinstock, MD


Morbidity and Mortality Weekly Report. 2015;64(44):1241-1245. 

In This Article


Congenital syphilis (CS) occurs when a mother infected with syphilis transmits the infection to her child during pregnancy. CS can cause severe illness, miscarriage, stillbirth, and early infant death. However, among pregnant women with syphilis who deliver after 20 weeks gestation, maternal treatment with penicillin is 98% effective at preventing CS.[1] In the United States, the rate of CS decreased during 1991–2005 but increased slightly during 2005–2008.[2] To assess recent trends in CS, CDC analyzed national surveillance data reported during 2008–2014, calculated rates, and described selected characteristics of infants with CS and their mothers. The overall rate of reported CS decreased from 10.5 to 8.4 cases per 100,000 live births during 2008–2012, and then increased to 11.6 cases per 100,000 live births in 2014, the highest CS rate reported since 2001. From 2012 to 2014, reported cases and rates of CS increased across all regions of the United States. To reduce CS, the timely identification of and response to increases in syphilis among women of reproductive age and men who have sex with women are essential. All women should have access to quality prenatal care, including syphilis screening and adequate treatment, during pregnancy.[3]

CS is a nationally notifiable disease with case data reported to CDC by all 50 states and the District of Columbia through the National Notifiable Diseases Surveillance System.* For surveillance purposes, the definition of a CS case includes both stillbirths and infants with clinical evidence of CS, as well as stillbirths and infants born to mothers with untreated or inadequately treated syphilis, regardless of the infant's manifestation of clinical disease. CDC analyzed cases of CS reported during 2008–2014, describing selected demographic and clinical features of infants with CS and their mothers. CS rates were calculated as cases per 100,000 live births by using U.S. natality data published by the National Center for Health Statistics.[4] Rates of primary and secondary (P&S) syphilis, a measure that combines two stages of recently acquired infectious syphilis to monitor incident disease, were calculated among women as cases per 100,000 women by using U.S. Census population estimates.[5] Because 2014 natality and Census data were not yet available, CS and P&S rates for 2014 were calculated by using 2013 denominators.

*During 2008–2014, a case of congenital syphilis (CS) was defined as illness in an infant from whom lesional, placental, umbilical cord, or autopsy material specimens demonstrated Treponema pallidum by darkfield microscopy, fluorescent antibody, or other specific stain; an infant whose mother had untreated or inadequately treated syphilis at delivery; or an infant or child who has a reactive treponemal test for syphilis and any of the following: 1) evidence of CS on physical examination; 2) evidence of CS on radiographs of long bones; 3) a reactive cerebrospinal fluid (CSF) venereal disease research laboratory test; 4) an elevated CSF cell count or protein (without other causes); or 5) a reactive fluorescent treponemal antibody absorbed-19S-immunoblobulin M (IgM) antibody test or IgM enzyme-linked immunosorbent assay. This definition includes fetal deaths occurring after 20-weeks gestation or in which the fetus weighed >500 grams and the mother had untreated or inadequately treated syphilis at delivery. Adequate treatment was defined as completion of a penicillin-based regimen, in accordance with CDC treatment guidelines, appropriate for the mother's stage of infection, and initiated ≥30 days before delivery. A slightly modified case definition took effect in 2015 and can be accessed at These changes add polymerase chain reaction as an acceptable method for demonstrating the presence of T. pallidum in specimens; remove the use of IgM antibody testing and assays for defining cases of CS; and add suggested parameters for defining abnormal CSF cell count and protein levels in infants.