What is Neonatal Herpes?

Neonatal herpes is a rare medical condition in which the herpes simplex virus is transmitted from a pregnant woman to her child, usually around the time of birth. Though neonatal herpes is rare, affecting only one newborn child in every 3,000 to 20,000 live births, it is a serious and often fatal condition. A newborn usually becomes infected with herpes by coming into contact with infected secretions in the birth canal, though five percent of infants with herpes are infected in the womb, and ten percent are infected just after birth. Neonatal herpes is more common when the mother acquires herpes during the pregnancy.

There are three different manifestations of neonatal herpes: skin, eyes, and mouth (SEM) herpes, disseminated (DIS) herpes, and central nervous system (CNS) herpes. SEM herpes has the best prognosis of the three, though if untreated, it can progress to one of the other, more dangerous, forms of neonatal herpes. SEM herpes is characterized by external lesions, especially on the face, and on areas associated with trauma or surgery. Disseminated herpes, on the other hand, affects the inner organs, particularly the liver. DIS herpes has the highest mortality rate of all forms of neonatal herpes.

CNS herpes is associated with the highest morbidity rate of the three types of neonatal herpes. In CNS herpes, the spinal cord and brain are infected with the herpes virus. This form of neonatal herpes may present with seizures or muscle tremors, lethargy, irritability, and difficulty feeding.

Over the past few decades, the mortality rate of herpes simplex in infants has been greatly reduced through the use of antiviral medications including acyclovir and vidarabine. However, in order for such medications to be effective, it is very important for the infection to be diagnosed early. Unfortunately, 20 to 40 percent of infected infants cannot receive early treatment because they do not have visible symptoms. If it is known that the mother acquired herpes during her pregnancy, delivery by Caesarean section can help reduce the infant's chance of being infected with the herpes simplex virus. It is very unlikely for a woman with recurrent herpes, acquired before her pregnancy, to pass the infection to her child, so Caesarean section is not indicated in such cases.