Herpes simplex virus: prevalence in placental tissue and incidence in neonatal cord blood samples

Herpes simplex virus (HSV) infection is one of the most prevalent infectious diseases worldwide, with HSV-2 being primarily associated with genital infections. HSV-2 is believed to account for the majority of cases of neonatal herpes, which may cause diverse of complications in infected newborns. The present study sought to estimate the prevalence of HSV-2 in placental tissue samples and the incidence of HSV-2 in the umbilical cord blood of newborn infants. Placental tissue samples from 201 women (maternal-side and fetal-side = 402 specimens) and 184 neonatal cord blood samples, all collected at the obstetric ward of a University hospital were studied. HSV-2 was detected by means of nested PCR. The prevalence of HSV-2 in placental samples was 9.0% (n = 18), and the incidence of neonatal HSV-2 infection was 1.1% (n = 2). All HSV-2-positive patients were asymptomatic at the time of delivery and none reported genital herpes. Women with a time between rupture of membranes and delivery of ≥360 min had an approximately fourfold risk of HSV-2 infection in the placental tissue (95% CI 0.93-5.66, P = 0.01). These results suggest that HSV-2 is present in the placenta of asymptomatic women and that a risk of transmission to the neonate exists. New strategies must be implemented for the management of asymptomatic patients who are capable of transmitting the virus to the newborn.