Neonatal Herpes (HSV-2)
Overview
Plain-Language Overview
Neonatal Herpes (HSV-2) is a serious viral infection that affects newborn babies, primarily involving the skin, eyes, mouth, and central nervous system. It is caused by the herpes simplex virus type 2, which can be transmitted from mother to infant during childbirth. This infection can lead to blistering skin lesions, eye damage, and severe brain inflammation called encephalitis. The condition can cause significant health problems, including seizures and developmental delays. Early signs often include fever, irritability, and poor feeding. Prompt diagnosis and treatment are critical to reduce the risk of long-term complications or death.
Clinical Definition
Neonatal Herpes (HSV-2) is a viral infection in newborns caused by vertical transmission of herpes simplex virus type 2 during delivery. The core pathology involves viral replication in epithelial cells and subsequent dissemination to the central nervous system and other organs. It presents in three forms: localized skin, eye, and mouth disease, disseminated infection involving multiple organs, and central nervous system disease with encephalitis. The infection is significant due to its high morbidity and mortality if untreated. Diagnosis is often delayed because initial symptoms can be nonspecific. The disease requires urgent antiviral therapy to improve outcomes and prevent severe neurological damage.
Inciting Event
Exposure to HSV-2 virus during vaginal delivery through an infected birth canal is the primary inciting event.
Primary maternal genital HSV-2 infection in late pregnancy triggers high viral shedding at delivery.
Membrane rupture prior to delivery allows viral ascent into the amniotic fluid and fetus.
Use of instrumental delivery (forceps or vacuum) can cause mucosal trauma facilitating viral entry.
Latency Period
Symptoms typically develop within 2 to 12 days after birth following exposure to HSV-2 at delivery.
The incubation period reflects time for viral replication and spread to cause clinical disease.
Latency is generally absent in neonatal infection as this represents primary exposure rather than reactivation.
Diagnostic Delay
Early symptoms are often nonspecific (fever, lethargy), leading to misdiagnosis as bacterial sepsis.
Lack of visible vesicular skin lesions in some cases delays clinical suspicion of HSV-2.
Limited access to PCR testing for HSV DNA in cerebrospinal fluid or lesions can postpone diagnosis.
Overlap with other neonatal infections causes initial treatment to focus on bacterial pathogens.
Clinical Presentation
Signs & Symptoms
Fever and irritability are common early systemic signs
Vesicular rash appearing within the first 2 weeks of life
Respiratory distress in disseminated disease
Seizures and altered mental status indicating CNS involvement
Poor feeding and lethargy reflecting systemic illness
History of Present Illness
Initial presentation includes fever, irritability, poor feeding, and lethargy within the first 1-2 weeks of life.
Development of vesicular skin lesions on the scalp, face, or trunk is a hallmark but may be absent early.
Progression to seizures, respiratory distress, or jaundice indicates CNS or disseminated involvement.
Symptoms often worsen rapidly over days without antiviral treatment.
Past Medical History
Maternal history of genital herpes or recent genital lesions during pregnancy is a key risk factor.
History of prolonged rupture of membranes or complicated delivery increases neonatal risk.
No prior neonatal illnesses typically precede HSV-2 infection as it is acquired perinatally.
Lack of maternal antiviral prophylaxis during pregnancy may predispose to neonatal infection.
Family History
Family history is generally not contributory as neonatal HSV-2 is an acquired infection.
No known heritable syndromes are associated with increased susceptibility to neonatal HSV-2.
Maternal history of recurrent genital herpes may be present but does not imply genetic transmission.
Physical Exam Findings
Vesicular skin lesions on an erythematous base, often clustered and localized to the scalp, face, or trunk
Conjunctivitis or keratoconjunctivitis with eyelid swelling and discharge
Hepatosplenomegaly indicating systemic involvement
Lethargy and poor feeding reflecting central nervous system involvement
Seizures or abnormal tone in cases of disseminated or CNS disease
Diagnostic Workup
Diagnostic Criteria
Diagnosis is established by detecting HSV DNA via polymerase chain reaction (PCR) from samples such as cerebrospinal fluid, skin lesions, or blood. Clinical suspicion arises with characteristic vesicular skin lesions in a neonate, especially with a history of maternal genital herpes. Additional supportive findings include positive viral culture from lesions and abnormal cerebrospinal fluid analysis in cases of CNS involvement. Imaging such as brain MRI may show findings consistent with herpes encephalitis. Early and accurate identification using PCR is the gold standard for confirming the diagnosis.
Pathophysiology
Key Mechanisms
Vertical transmission of herpes simplex virus type 2 (HSV-2) occurs during passage through an infected birth canal.
Viral replication in neonatal skin, mucous membranes, and central nervous system causes tissue damage and inflammation.
Latency and reactivation of HSV-2 in sensory ganglia contribute to recurrent disease but are less relevant in neonates.
Disseminated infection results from hematogenous spread of HSV-2 to multiple organs including liver, lungs, and brain.
Neonatal immune system immaturity leads to impaired viral clearance and increased severity of infection.
| Involvement | Details |
|---|---|
| Organs | Brain involvement leads to herpes simplex encephalitis, a severe complication of neonatal HSV-2 infection. |
Liver may be affected in disseminated neonatal herpes causing hepatitis and coagulopathy. | |
Lungs can be involved in disseminated infection leading to pneumonitis and respiratory distress. | |
| Tissues | Skin and mucous membranes are primary sites of viral replication and lesion formation in neonatal herpes. |
Central nervous system tissue is vulnerable to viral invasion causing encephalitis in disseminated disease. | |
| Cells | CD8+ T cells play a critical role in controlling HSV-2 infection by killing infected cells. |
Dendritic cells initiate the antiviral immune response by presenting viral antigens to T cells. | |
Neutrophils contribute to early innate immune defense but may also cause tissue damage. | |
| Chemical Mediators | Interferon-alpha is produced in response to HSV-2 infection and helps inhibit viral replication. |
Tumor necrosis factor-alpha (TNF-α) mediates inflammation and contributes to tissue damage in infected neonates. | |
Interleukin-6 (IL-6) is elevated during infection and promotes acute phase responses. |
Treatments
Pharmacological Treatments
Acyclovir
- Mechanism:
Inhibits viral DNA polymerase after phosphorylation by viral thymidine kinase, preventing HSV DNA replication.
- Side effects:
Nephrotoxicity
Neurotoxicity
Phlebitis
- Clinical role:
First-line
Non-pharmacological Treatments
Supportive care including fluid management and temperature regulation is essential in neonatal herpes.
Isolation precautions to prevent nosocomial spread of HSV-2 in neonatal units.
Prevention
Pharmacological Prevention
Maternal antiviral prophylaxis with acyclovir starting at 36 weeks gestation to reduce viral shedding
Intravenous acyclovir treatment for neonates with suspected or confirmed HSV infection
Suppressive antiviral therapy postpartum in mothers with recurrent genital HSV to prevent transmission
Non-pharmacological Prevention
Cesarean delivery recommended if active genital HSV lesions or prodromal symptoms are present at labor
Avoidance of invasive fetal monitoring during delivery to reduce transmission risk
Screening pregnant women for HSV history and symptoms to identify risk
Strict hygiene and contact precautions to prevent nosocomial neonatal HSV transmission
Outcome & Complications
Complications
Disseminated HSV infection causing multi-organ failure
HSV encephalitis leading to seizures and coma
Disseminated intravascular coagulation in severe cases
Permanent neurological damage from CNS involvement
Death if untreated or in severe disseminated disease
| Short-term Sequelae | Long-term Sequelae |
|---|---|
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Differential Diagnoses
Neonatal Herpes (HSV-2) versus Neonatal Bacterial Sepsis
Neonatal Herpes (HSV-2) | Neonatal Bacterial Sepsis |
|---|---|
Caused by herpes simplex virus type 2 | Commonly caused by Group B Streptococcus or Escherichia coli |
May present with vesicular skin lesions and CNS involvement | Rapid onset of systemic signs with high fever and shock |
Positive PCR or culture for HSV from skin lesions or CSF | Positive blood cultures for bacteria |
Neonatal Herpes (HSV-2) versus Neonatal Varicella (Chickenpox)
Neonatal Herpes (HSV-2) | Neonatal Varicella (Chickenpox) |
|---|---|
Maternal genital HSV infection or exposure during delivery | Maternal varicella infection during pregnancy or peripartum |
Painful grouped vesicles on erythematous base | Pruritic vesicular rash in various stages of healing |
Positive PCR or culture for HSV | Positive PCR or direct fluorescent antibody test for varicella-zoster virus |
Neonatal Herpes (HSV-2) versus Neonatal Candida Infection
Neonatal Herpes (HSV-2) | Neonatal Candida Infection |
|---|---|
Grouped vesicular lesions on skin and mucous membranes | Erythematous rash with satellite pustules, often in diaper area |
Infection with herpes simplex virus type 2 | Infection with Candida albicans or other Candida species |
Positive viral culture or PCR for HSV | Positive fungal culture or KOH prep showing yeast and pseudohyphae |
Neonatal Herpes (HSV-2) versus Neonatal Enterovirus Infection
Neonatal Herpes (HSV-2) | Neonatal Enterovirus Infection |
|---|---|
Often presents within first 2-3 weeks but can be variable | Typically presents within first 1-2 weeks of life |
Fever with characteristic vesicular skin lesions and possible CNS disease | Fever, rash, and aseptic meningitis without vesicular lesions |
Positive PCR or culture for HSV DNA | Positive PCR for enterovirus RNA in CSF or blood |
Neonatal Herpes (HSV-2) versus Neonatal Impetigo
Neonatal Herpes (HSV-2) | Neonatal Impetigo |
|---|---|
Grouped vesicular lesions on erythematous base | Honey-colored crusted erosions without vesicles |
Caused by herpes simplex virus type 2 | Caused by Staphylococcus aureus or Streptococcus pyogenes |
Positive viral culture or PCR for HSV | Positive bacterial culture from skin lesions |