Understanding Herpes in Newborn Infants

Infants born to women who are carriers of the herpes simplex virus are at risk of contracting neonatal herpes, a potentially lethal infection. Neonatal herpes occurs in 1 in 3,200 live births in the Pacific Northwest United States. There are about 1,500 cases of neonatal HSV in the U.S. annually. Approximately 85% of neonates acquire herpes through intrapartum infection via contact with the herpes simplex virus in the birth canal.

Approximately 5% of cases newborns with herpes have acquired the HSV infection while in the uterus. This happens most commonly when the mother gets her very first HSV infection during her pregnancy.

Around 10% of infants develop a postnatal infection. The acquisition of neonatal herpes following birth can occur from:

-contact with orolabial herpes

-contact with herpes infection of the finger (herpetic whitlow)

-contact with herpes affecting the breast.

There is a spectrum of neonatal disease conditions caused by the herpes simplex virus. This disease spectrum includes:

1. Skin, eye and mouth disease

2. Central nervous system (CNS) disease

3. Disseminated disease

About 45% of infants will develop skin, eye, and mouth herpes lesions. This form of neonatal herpes does not affect the internal organs.

30% of infants with neonatal HSV will develop central nervous system (CNS) disease. Neonatal CNS herpes is manifest by:

-seizures

-lethargy

-irritability

-tremors

-poor feeding

-temperature instability

-a bulging fontanelle

Around 25% of neonatal herpes is of the most severe form, disseminated disease. Infants with disseminated herpes infection have multi-organ involvement. These infants can die from severe coagulopathy (defective blood clotting), liver dysfunction, and/or pulmonary failure.

The treatment of neonatal HSV is limited to intravenous acyclovir. In infants with skin, eye, and mouth disease with limited organ involvement, IV acyclovir is quite effective. A reduction in the morbidity and mortality of this form of neonatal herpes has been seen since acyclovir became available.

The treatment of disseminated HSV infection and CNS HSV disease in neonates has had significantly less success. There has been little improvement in outcomes despite early intervention with high dose IV acyclovir.

-40% of newborns with CNS disease have severe neurologic damage.

-30% of newborns with disseminated HSV disease die.

Given these heartbreaking statistics for the treatment of neonatal HSV, it becomes obvious that prevention is critical. In order to prevent the infant acquisition of herpes it is first necessary that current genital herpes and/or a history of herpes are recognized in the pregnant woman. The pregnancy and delivery of a woman with HSV must then be managed according to established guidelines for genital herpes during pregnancy.