Objective: To investigate the prevalence and level of genital herpes simplex virus (HSV) among women at delivery.
Design, patients, and setting: A prospective analysis of HSV by culture and by polymerase chain reaction (PCR) of genital specimens and by HSV serologic studies in 100 asymptomatic women in labor; prospective analysis of HSV by PCR among 50 seronegative nonpregnant women at a student health center; and retrospective analysis of genital specimens for HSV by PCR from 17 HSV culture-positive women with uninfected neonates and from two HSV culture-negative women with HSV-infected neonates. All pregnant women were at a university hospital.
Main outcome measures: Presence of HSV by culture and levels of HSV by quantitative, type-specific PCR in cervical and vulvar specimens; HSV serologic testing by Western blot.
Results: All of the 100 asymptomatic women in labor who were studied prospectively were HSV culture negative. In nine HSV was recovered by PCR. Herpes simplex virus was recovered by PCR in one of the 50 seronegative nonpregnant women; she soon became seropositive. All 17 culture-positive women had HSV recovered by PCR. High levels of HSV DNA were obtained by PCR from the two culture-negative women with infected neonates. Among those from whom HSV was recovered by PCR, HSV DNA levels were 250 times higher from culture-positive samples than from culture-negative samples (11,571 genome equivalents vs 46 genome equivalents; P < .001).
Conclusions: The frequency of infant exposure to HSV DNA-containing secretions from HSV-seropositive mothers is about eight times higher than previously reported using HSV culture methods. High maternal levels of HSV DNA may be associated with an increased frequency of transmission of HSV to the infant.