Serologic and virologic evidence for frequent intrauterine transmission of human parvovirus B19 with a primary maternal infection during pregnancy.

OBJECTIVE: To define the intrauterine viral transmission rate during primary maternal parvovirus B19 infection and identify factors that may influence this rate. METHODS: Forty-three pregnant women at two medical centers were identified with a primary B19 infection and followed to delivery. At delivery maternal and infant (umbilical cord) blood was obtained for B19 serologic and virologic PCR testing. RESULTS: All of the women delivered healthy infants at term and none was hydropic. Overall 22 (51%) of the 43 infants had some evidence of a congenital B19 infection. B19-specific IgM was detected in 11 infants at delivery, B19 IgA was detected in 10 and B19 DNA was detectable by PCR in 11 infants. One infant was negative at birth but became positive for IgM, IgA and PCR at 6 weeks of age. No association was found between the likelihood of intrauterine infection and: maternal age; symptomatic maternal infection; method of delivery; maternal IgG titer at delivery; maternal IgG avidity at delivery; or maternal viremia at delivery. Intrauterine infection was associated with maternal IgM positivity at delivery; this association may have been a result of maternal infection occurring later in gestation. CONCLUSION: Although the incidence of intrauterine hydrops and fetal demise after maternal infection is low, there is a high rate of intrauterine viral infection that occurs throughout gestation and yields newborns who, although infected in utero, are asymptomatic at birth.

Comparison of profound biotinidase deficiency in children ascertained clinically and by newborn screening using a simple method of accurately determining residual biotinidase activity.

We describe a method for more accurately determining residual biotinidase activity in sera of individuals with profound biotinidase deficiency. Using this method we found that there is a statistically significant difference in the means of residual serum enzyme activities of symptomatic children and those identified by newborn screening. A subgroup of children identified by screening have activities higher than any of the symptomatic population. These children may develop mild symptoms, may develop symptoms later in life, or may not develop symptoms at all.