A vesicular rash
follows lasting 7-10 days. Infectious period begins 48 hours before the
rash appears.
Rash crusts over and
is no longer infectious.
Maternal giant cell
pneumonia, a serious complication occurs in 5-10% of adults (1).
Pneumonia usually occurs 2-6 days after the onset of the rash. A maternal
mortality of 6% has been reported (2).
This occurs when the
mother gets infected close to delivery of following birth.
If varicella occurs
within 5 days of delivery or up to 2 days after delivery, the newborn
infant has a 20% chance of developing systemic varicella. This has a 30%
fatality rate.
The attack rate is 25%
to 50%, and the incubation period averages 11 days (range 1 to 16 days).
The severity of
infection is directly proportional to the presence and amount of
placentally acquired maternal antibody. As maternal antibody is not
transported across the placenta in sufficient quantities until the 5th
day of maternal infection, neonates born 5 days or less from the onset of
maternal disease receive no protective maternal antibody. Similarly,
women who have onset of disease within 2 days following delivery were
presumably viremic antepartum, so their infants will also be born without
antibody.
REFERENCES
Gibbs RS. Fetal infection from
non-torch viruses. In: Reece EA, Hobbins JC, Mahoney MJ, Petrie RH (eds).
Medicine of the fetus and mother. Philadelphia, JB Lippincott Company,
1992:365-375.
British Royal College of
Obstetricians and Gynecologists: Chicken pox in pregnancy. Guideline No.
13. July 1997.