New Tests for Diagnosing Syphilis in Newborns

A study has demonstrated that two new blood tests can detect either neonatal antibodies to the syphilis bacterium or the DNA of the syphilis organism itself as predictors of central-nervous system infection. The findings were published in the June 6, 2002, issue of The New England Journal of Medicine.

The two tests used in the study, immunoglobin M (IgM) immunoblotting and polymerase chain reaction (PCR) detected all cases of central-nervous-system infection in a group of 148 infants studied. The babies were all born to syphilis-infected mothers.

The tests were developed by researchers at the University of Texas (UT) Southwestern Medical Center (Dallas, USA). They say the tests provide the first valid data on which to base an effective, cost-efficient neonatal treatment regimen for congenital syphilis. A pregnant woman with syphilis has about a 60-80% chance of infecting her fetus. Infants born to mothers with syphilis are traditionally hospitalized for multiple daily injections of penicillin over a 10-day period because physical exams and conventional laboratory tests are unable to detect all cases. The most accurate lab test until now required a three-month incubation period.

Earlier research at UT Southwestern had suggested that congenital syphilis might stimulate a detectable reaction by the newborn's immune system. "We believed we could evaluate this by searching for the presence in neonatal blood of the infant's IgM antibodies,” said Dr. Michael Norgard, UT chairman of microbiology and a co-author of the study. The study confirmed this theory.




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