Materno-fetal transmission occurs in about 5-6% of infected mothers. Older mothers with multiple previous pregnancies have a lower rate of transmission. Only about half of the infants are symptomatic.
Mothers are considered infected if one or both of the following is present:
(1) indirect hemagglutination with a titer >= 1:16
(2) immunofluorescence with a titer >= 1:40
Neonates are considered infected if one or more of the following is present in specimens collected at birth or during the 30 days after delivery:
(1) parasites seen in buffy coats prepared from 1 or more microhematocrit heparinized tubes (4 tubes collected, each 50 µL)
(2) positive hemoculture of 2 mL of blood
(3) positive PCR (if done on a sample other than cord blood)
where:
• I would think that the mother would be considered positive if buffy coats, PCR or hemoculture were performed.
