Neonatal herpes: the serious infection that is transmitted to the baby through childbirth 2026

Neonatal herpes simplex virus (HSV) infection can be due to HSV type 1 or 2, the latter being the most common. Most HSV infections (87%) are transmitted to the fetus through the birth canal, with the fetus being affected in the first two trimesters of pregnancy through hematogenous transmission being exceptional. There is the possibility of postnatal contamination through contact with non-genital herpes lesions (10% of neonatal herpes cases).

In adults, type 1 recovers more frequently from oral lesions and type 2 from genital lesions. It has been estimated that the incidence of herpes simplex infection in the neonatal period is 1 case per 3,000-20,000 births.

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Neonatal herpes simplex: how it is transmitted

HSV is usually transmitted during childbirth through the infected maternal genital canal. Mothers of newborns with HSV infection tend to present with a newly acquired genital infection, but many may have had no symptoms prior to delivery.

They may also be responsible for some cases of neonatal infection, transplacental transmission of the virus and intra-hospital spread from one newborn to another through hospital staff. This last transmission mechanism is very rare today.

Neonatal herpes simplex: symptoms

The clinical manifestations of the disease occur between the first and second weeks of life, and newborns may present with a local condition or a disseminated disease.

Typical skin lesions of HSV infection are vesicles. This term refers to the presence of raised skin lesions with transparent liquid content.

It is important that the doctor makes an early diagnosis of the disease that leads him to establish a specific treatment for it and thus be able to prevent its evolution into more extensive clinical forms and with a life-threatening prognosis.

Newborns with disseminated disease and involvement of visceral organs may present: encephalitis, hepatitis, pneumonitis, disseminated intravascular coagulation, or a combination of these manifestations.

Other signs that may appear, singly or in combination, are: thermal instability, lethargy, hypotonia, respiratory difficulty, apnea and seizures.

The clinical diagnosis is confirmed by determining HSV by PCR of the vesicle contents.

Other diagnostic techniques that can be used are: immunofluorescence or electron microscopy. In addition to skin vesicles, the nasopharynx, eyes or cerebrospinal fluid (CSF) can also be analyzed.

Mortality is low in patients with a local disease limited to the skin, eyes or mouth. However, without systemic treatment with acyclovir, many will progress to disseminated or CNS disease. The mortality rate of untreated disseminated disease is 85%.

Neonatal herpes simplex: how to avoid it?

Lacesection in women at high risk of transmission, such as those with active genital lesions present at the time of delivery, has been shown to reduce transmission. The use of fetal scalp monitors during labor is not recommended when the mother is suspected of having genital herpes.

Whenever a woman has an active genital herpes simplex infection at the time of childbirth, it is recommended to perform a prophylactic cesarean section for the benefit of the fetus, regardless of the time elapsed since the rupture of the membranes. This is especially important in cases of primary maternal herpes infection. The use of acyclovir from 36 weeks reduces the reactivation of the virus in the mother. As soon as the diagnosis of infection is suspected in the neonate, acyclovir 20 mg/kg should be administered IV every 8 hours for 14-21 days. In the disseminated disease group, this treatment reduces mortality from 80 to 15% and neurological sequelae from 100 to 40%. In case of ocular involvement, local treatment will also be administered. The affected newborn must be isolated to prevent nosocomial transmission.

Rosa M. Díaz Díaz is a professor at the European University, and a doctor of Dermatology at the Infanta Sofía San Sebastián de los Reyes Hospital in Madrid.