Herpes simplex virus (HSV) infects one per 3,000 to 20,000 live births according to Dr. Carolyn Rudnick's March 2002 article in the journal "American Family Physician." HSV infection has periods of dormancy in the body with recurrent infectious periods when viral particles are shed and can infect others. Pregnant women are more susceptible to new infections and, if already infected, are more likely to have a recurrence during pregnancy, which makes fetal infection more likely. Fetal infection can cause pregnancy complications and miscarriage, fetal developmental defects, pre-term labor and possibly death of the newborn infant. Effects on the fetus can be divided into three categories based on severity.
Infection Limited to the Skin, Mouth and Eyes
Forty-five percent of newborn HSV infection is limited to the skin, eyes and mouth, and survival with treatment is almost 100 percent. However, 2 percent of these babies have infections which get worse and progress to other systems. Undetected exposure to HSV at birth can lead to delayed symptoms of infection becoming visible several days or a week later. Newborns may not exhibit signs of HSV infection for as much as 11 days after delivery. If your baby has a fever, does not want to eat, is lethargic or has sores on his mouth, face or genital area, let your physician know immediately. The anti-viral medication acyclovir, at a dose of 30 to 60 mg/kg/day for 10 to 21 days, is used to treat newborns.
The greatest risk for maternal to fetal transmission is when an existing HSV infection flares at the time of labor, shedding virus into the birth canal, exposing the mucous membranes of the fetus to maternal genital secretions during vaginal delivery. Ninety percent of cases of fetal HSV infection occur during delivery. Birth by Cesarean section is recommended if labor occurs during an episode of viral shedding to reduce the risk of exposing the baby to infected secretions in the birth canal.
Infection of the Nervous System and Brain
Thirty-five percent of infected newborns have seizures which indicate that the central nervous system is affected. Newborns with infection in the brain (encephalitis) may also have infections of the skin, eye and mouth. While 85 percent of these babies survive with treatment, more than half have lingering problems which can include brain damage, retardation and blindness. Signs of seizures shortly after birth suggest that the infection began in utero by maternal to placental transmission. Ten percent of HSV fetal infections are transmitted through the placenta to the fetus during pregnancy. Women who become newly infected with the HSV virus in the third trimester are more likely to spread the virus to the fetus in utero because the levels of virus in the blood are highest in a new infection.
Widely Disseminated Infection of Multiple Organ Systems
If infection has spread to multiple organ systems, babies have only a 50 percent chance of surviving, even with anti-viral therapy. Infants with this most severe form of HSV infection typically have infections in the central nervous system and other organs including the lungs, liver, adrenal glands, skin, eye or mouth. If babies with encephalitis and other organ infections do survive, these children are more likely to have long term health problems including seizures, blindness, learning disabilities and problems with muscle control.
