Seroreversion of the serological tests for syphilis in the newborns born to treated syphilitic mothers

Abstract

BACKGROUND: IgG antibodies from mothers adequately treated for syphilis can cross the placenta and appear in the sera of healthy newborns without infection. In such infants, a false diagnosis of congenital syphilis is often made. We have designed a retrospective survey to determine the time of seroreversion of the serological tests for syphilis (STS) in uninfected newborns born to mothers who were adequately treated for syphilis. MATERIALS AND METHODS: Fifty two seropositive, untreated newborns born to 51 mothers treated for syphilis were studied. The newborns were followed at 1, 3, 6, 9, and 12 months of age until seroreversion was detected. The VDRL test was followed until 12 months in 12 of the 22 newborns who were positive at birth, the TPHA in 21 of the 46 newborns, and the FTA-ABS test in 22 of the 48 newborns. RESULTS: In the first serological tests done within 1 month after birth, the VDRL was positive in 22 newborns (42%), the TPHA in 46 (88%), and FTA-ABS in 48 (92%). The VDRL seroreverted within 6 months after birth in 84%, and within 1 year in 100%. The TPHA test seroreverted in 95% within 1 year after birth. The FTA-ABS test seroreverted in 100% within 1 year after birth. CONCLUSIONS: In most seropositive, untreated newborns born to treated mothers the VDRL became negative within 6 months after birth and the TPHA and FTA-ABS within 1 year. This result is consistent with current Centers for Disease Control (CDC) guidelines. However, although the CDC guidelines are adequate in general, we think that some revision is desirable concerning the IgM test and combination of the test results in order to rule out congenital syphilis in seropositive, nonsymptomatic newborns born to the treated mothers.