Use of routine viral cultures at delivery to identify neonates exposed to herpes simplex virus.

We obtained specimens for viral culture from mothers, infants, or both at the time of 6904 deliveries, without regard to the mothers' history of genital herpes. Herpes simplex virus (HSV) was recovered in cultured specimens from 14 of the 6904 deliveries (0.20 percent); all 14 mothers were asymptomatic. All viral isolates were herpes simplex virus type 2 (HSV-2). Only 1 of the 14 women (7 percent) had a history of genital herpes, whereas 12 (86 percent) had serologic evidence of a previous infection with HSV-2. None of the infants born to these 12 women contracted neonatal herpes. However, one of the two infants born to women with serologic evidence of a primary HSV infection at the time of delivery contracted neonatal herpes. Our findings show that most infants at risk of exposure to HSV at delivery will not be identified if concern about asymptomatic shedding of virus is limited to women with a history of genital herpes infection. Most neonatal exposure to an asymptomatic maternal HSV infection at delivery is not predictable or preventable. Therefore, physicians caring for newborns need to consider neonatal herpes in the differential diagnosis when infants become ill during the first weeks of life, regardless of the presence or absence of identifiable risk factors for HSV infection.