Epidemic syphilis: maternal factors associated with congenital infection

Little is known about which cases of maternal syphilis will affect the newborn. Because of the current epidemic of syphilis in pregnancy in our city, we sought to identify risk factors during pregnancy associated with congenital infection.

We reviewed 253 cases of maternal syphilis prospectively identified over a 1-year period. On the basis of neonatal diagnosis, these data were divided into two groups, those without evidence of presumptive congenital syphilis and those with evidence of presumptive congenital syphilis. Presumptive congenital syphilis was defined according to the Centers for Disease Control and Prevention surveillance case definition. Cases with bloody spinal taps and cases of suspected congenital syphilis that did not meet these criteria were excluded. Venereal Disease Research Laboratory titers are given as the inverse of the geometric mean.

Venereal Disease Research Laboratory titer at time of diagnosis and unknown duration of disease were risk factors for congenital syphilis. There was a significantly decreased rate of congenital syphilis with single-dose therapy if disease length was < 1 year (p < 0.005). Unknown duration of disease was associated with 67.9% and 48.6% rates of congenital syphilis with one- and three-dose therapy respectively. There was a 28% incidence of preterm birth.

Our study suggests an alarming rate of failure of current therapy to prevent congenital syphilis. Venereal Disease Research Laboratory titer at time of diagnosis and unknown duration of disease are risk factors for congenital syphilis. The high rate of presumptive congenital syphilis in the unknown duration group indicates that identification before or earlier in pregnancy will be necessary to prevent devastating consequences for the neonate.