CONGENITALLY ACQUIRED INFECTIONS

Herpes Simplex Virus (HSV) 1. Background a. HSV type 2 is the most common cause of neonatal herpes disease. b. Transmission is usually during vaginal birth by an infected maternal genital tract; may also be an ascending infection through the amniotic membranes (ruptured or intact) i. If a pregnant woman has active genital lesions, a cesarean delivery can reduce the risk of transmission to the neonate. ii. Suppressive therapy with oral acyclovir or valacyclovir given near the end of pregnancy to a woman with a history of HSV infection can reduce, but not eliminate, the risk of transmission. c. Risk of transmission to the neonate i. Highest (60%) in those born to mothers with first-episode primary genital infection, followed by those born to mothers with first-episode nonprimary infection (25%) ii. Transmission from a mother with recurrent HSV infection is low (less than 2%).

Diagnosis a. Definitive diagnosis – Isolation of HSV by culture i. Scraping of skin vesicles for culture ii. “Surface cultures” – Swabs of the conjunctivae, mouth, nasopharynx, and rectum performed at about 24 hours after birth b. PCR testing of CSF is used for confirming CNS involvement. i. Persistently positive PCR assay of the CSF after treatment is associated with poor outcomes. ii. A repeat specimen should be tested near the end of the treatment course to confirm the clearance of HSV from the CSF; therapy should continue until the result is negative. c. PCR testing of blood – Usefulness for guiding the length of therapy is unknown.