Do Pregnant Women with Positive Treponemal and Persistently Negative Nontreponemal Tests Transmit Syphilis to Their Babies? An Analysis of Congenital Syphilis (CS) Surveillance Data

Background: Screening pregnant women starting with treponemal tests identifies some with positive treponemal tests and negative nontreponemal tests who would not be identified if screening started with a nontreponemal test.  The risk of  transmission to an infant from these women is thought to be low.

Objectives: Determine if there is a risk of CS in infants born to mothers with a positive treponemal test and persistently negative nontreponemal tests.

Methods: Before 1988, CS definition focused on children likely to be infected (Kaufman criteria).  Since then, the definition changed to include all children born to mothers with untreated syphilis.  We reviewed line-listed cases of CS reported to CDC (birthdates 1991-2009) to see if any:  1) were born to mothers with persistently negative nontreponemal tests and 2) had definite or probable CS according to the Kaufman criteria.

Results: The most convincing cases of CS were 1,271 stillbirths and 284 confirmed cases; none had mothers with persistently negative nontreponemal tests.  Also, 47 US-born children were diagnosed with CS at age >1 yr, nontreponemal test results were available for 14 mothers—all were positive.  Of 22,308 other cases, 89 had mothers with only negative nontreponemal tests recorded after birth.  Two of the 89 infants had positive nontreponemal tests (specifically recorded since 2004) (titers 1:1), but no signs/findings.  Fifteen had signs/findings:  most convincing, one had x-ray findings and elevated CSF protein/cell count (but the report form was not located to be checked for coding errors); 2 had “signs of CS”, but their mothers were not persistently negative--they were only tested once within 3 days of birth; 12 had less specific findings.

Conclusions: Based on surveillance information, one child whose mother had persistently negative nontreponemal tests might meet Kaufman “probable” criteria. 

Implications for Programs, Policy, and Research: Infants born to mothers with positive treponemal and persistently negative nontreponemal tests are unlikely to be infected.