Herpes is a well-known and common disease in adults. However, when a baby or an infant is infected with herpes, the situation becomes harder to manage as their bodies differ from that of an adult, and they're known to be more vulnerable and sensitive to infections. 

The question here is: how does herpes affect infants, and are the symptoms the same as those of adults?

What is herpes?

Herpes is a viral disease caused by the Herpes Simplex Virus (HSV). There are two types: Herpes Simplex 1 (HSV-1), also known as oral herpes, which affects the mouth or face, causing cold sores to appear, and Herpes Simplex 2 (HSV-2), known as genital herpes, which is a sexually transmitted infection that causes skin sores when contacting the genitals of an infected person.¹

Neonatal herpes

Infants can get infected with herpes in various ways, and unfortunately, this can affect them severely. It is estimated that neonatal herpes occurs between 1 in 2000 and 1 in 20,000 live births, and this number might be increasing.²

Herpes in pregnancy

For a foetus to be infected with HSV, the mother must also be infected with HSV. There are three possibilities for this situation:

• Primary first episode: In this case, the mother gets infected with either HSV-1 or HSV-2 infection for the first time, with tender and painful blisters in the genitalia, urethra, vulva, vagina, cervix, or swollen lymph nodes. As this is her first infection with HSV, she has no antibodies against both HSV types. The risk for the neonate to contract HSV is high (30-50%)
• Non-primary first episode: The mother in this case, was previously infected with a subtype of HSV, and has the antibodies for it, but during the pregnancy, she has been infected with the other subtype. The risk for neonatal infection of HSV is explained to be similar to the primary infection
• Recurrent episodes: The mother has a reactivated genital HSV-1 or HSV-2 infection. Therefore, she already has antibodies for it, and the neonate also has them They have a protective effect, which makes the risk for neonatal infection of HSV lower, even if the mother is about to deliver³

Neonatal herpes transmission

Herpes is a tricky illness because it can be transmitted from the mother to the infant in three ways:

Intrauterine (transplacental) transmission

It occurs in about 5% of cases and can happen anytime during the pregnancy and before birth. The disease manifestations in the newborn already exist at birth or manifest within 48 hours after birth. The usual manifestations are the cutaneous signs (rash, skin vesicles, aplasia, and/or cutaneous hyper/hypopigmentation), eye damage (chorioretinitis, keratoconjunctivitis, and optic nerve atrophy), and central nervous system (CNS) manifestations (encephalopathy, intracranial calcifications, microcephaly, and hydranencephaly). There might be other symptoms, such as placental infarcts, hydrops fetalis, or in utero demise, which could lead to severe neurodevelopmental impairment or mortality.³

Perinatal infection

Perinatal infection occurs in about 85% of cases where the infection is present in the mother’s vaginal tract at the time of vaginal delivery, whether the mother presents as symptomatic or asymptomatic. 

Many factors influence perinatal transmission, such as the type of maternal HSV infection (primary or recurrent, and the primary is associated with a higher risk of transmission), maternal HSV antibody status, the duration of ruptured membranes, using a foetal scalp monitor, and the delivery method (usually, a caesarean section has a lower risk of transmission than vaginal delivery).³

Postnatal infection

Postnatal infections occur in about 10% of cases. The infant gets infected directly from contact with an infected person or an active HSV infection like herpes labialis. Neonates can also acquire HSV from a breast lesion while breastfeeding. 

Postnatal infection can be severe for neonates whose mothers have never been infected with HSV before, as these neonates won’t have any HSV antibodies from their mothers to protect them.³

Factors that affect neonatal herpes transmission

Risk of neonatal HSV following perinatal exposure

• Maternal genital infection: The risk of a recurrent infection in the first half of pregnancy is low (less than 2%). On the other hand, the risk increases at the end of pregnancy (the risk of primary infection is 57--60% and of non-primary or recurrent infection is 25%)
• Maternal HSV serostatus (the existence of HSV antibodies): The risk is lower when there are HSV antibodies in the mother’s blood and vice versa
• Mode of delivery: Vaginal delivery comes with a higher risk, while caesarean delivery lowers the risk
• Rupture of membrane (water breaking): The risk increases with prolonged duration
• Disruption of the cutaneous barrier ( using a foetal scalp electrode or other instrumentation during labour): This factor increases the risk
• HSV serotype: HSV-1 comes with a higher risk than HSV-2
• Maternal suppressive therapy: Giving the mother suppressive therapy during pregnancy lowers the risk
• Gestational age: The risk increases in the situation of preterm labour⁴

Risk of neonatal HSV following postnatal exposure

• Viral load: usually, the viral load in symptomatic patients is high, while it’s lower in asymptomatic primary infection, during asymptomatic reactivation episodes, and recurrent symptomatic recurrences (cold sores). Patients with recurrent cold sores can have a high viral load in their oral secretions at any time (during the symptomatic episode or between episodes). Therefore, these people pose a high risk when they’re asymptomatic and can infect neonates
• Intensity of exposure: The neonate being exposed to people with HSV is a high risk, especially when there is a high viral load with absent neonatal HSV antibodies
• Transplacentally transferred anti-HSV antibodies: these are the essential and only means of defence for neonates against HSV. Consequently, neonates with a higher anti-HSV antibody concentration are at a lower risk of getting infected. Moreover, the severity of the neonatal infection is dependent on the amount of these antibodies. Furthermore, the quantity of HSV antibodies transferred is related to the type of antibody itself, maternal health (less transferring in malnourished and HIV-infected mothers), and infant factors (less transferring in preterm infants)⁴

Clinical manifestations in neonates with HSV

Usually, symptoms in neonates with HSV appear between the first 4 to 6 weeks after birth. The manifestations are divided into three groups:

• Skin, eyes, and mouth (SEM) manifestations (35--85% of cases): The symptoms include vesicular lesions on the skin, eyes, or mouth without any other CNS or other organ manifestations, but if left untreated, it can increase the risk of CNS or disseminated manifestations. Skin lesions might start as clear vesicles (an erythematous base) and develop into clusters of vesicles. Mouth lesions can be distributed anywhere in the oral cavity. Eye manifestations might start as severe wetting of the eyes, weeping from apparent eye discomfort, and conjunctival erythema; the most prevalent ocular manifestations are blepharoconjunctivitis or keratitis, and sometimes chorioretinitis
• CNS involvement (one-third of cases): It might occur as a result of the spread from the olfactory and nasopharynx nerves to the brain or as a consequence of hematogenous spread in neonates with disseminated disease. The symptoms include seizures, tremors, irritability, lethargy, temperature instability, poor feeding, and a bulging fontanel
• Disseminated illness (25% of cases): The diseases here might spread to other organs, such as the brain, liver, lungs, and adrenals. The symptoms mostly include hepatic failure (with ascites and direct hyperbilirubinemia) and respiratory failure (with progressive interstitial pneumonitis and hemorrhagic pneumonitis, with or without effusion). Sometimes, disseminated intravascular coagulation might occur as well³

Herpes management

Herpes management in pregnancy

There are two main strategies for this situation: antiviral therapy and caesarean delivery, although both of them don’t fully eliminate the risk of neonatal herpes.

Postpartum management of herpes

• Parents and other caregivers who have HSV with active lesions at any site of the body must cover them and wash their hands before touching the infant
• Breastfeeding is not contraindicated if there aren’t lesions on the breasts
• Immediate diagnosis must be done directly to infants from infected mothers after birth to identify the disease as soon as possible, and the infants should be monitored to observe for any symptoms⁵

Herpes management in neonates

• In mothers with active genital herpes lesions following perinatal HSV exposure through birth, it’s recommended to give pre-emptive intravenous acyclovir to all the asymptomatic neonates with an unknown or no maternal history of herpes genitals
• In the case of postnatal HSV exposure, the risk of HSV diseases must be evaluated for each patient. Looking for maternal HSV antibodies is the first thing to do in addition to a detailed history to evaluate the exposure degree of the infant⁴

Summary

Neonatal herpes is a serious and life-threatening condition that can lead to dangerous complications. Although it’s unable to be prevented in many situations, precautions can be taken to protect the baby as much as possible. Testing and protecting yourselves and your babies from any possible exposure is paramount. We all love babies and want to kiss them and play with them, but sometimes the consequences are dreadful. Therefore, you must safeguard your child.