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Fetal and Neonatal Care
Neonatal herpes: recognition and urgent treatment
Clinical Overview and When to Suspect
Neonatal herpes simplex virus (HSV) infection is a rare but devastating condition with high morbidity and mortality if treatment is delayed.
— Skin, eye, mouth (SEM) disease (~45%)
— CNS disease with or without SEM (~30%)
— Disseminated disease involving multiple organs (~25%)
Incidence: ~1 in 3,000–20,000 live births in the U.S.
Caused by HSV-1 or HSV-2; historically HSV-2 predominates neonatally, but HSV-1 is increasing
Transmission: ~85% peripartum (contact with active genital lesions during delivery), ~5% in utero, ~10% postnatal (oral/cutaneous contact)
Three clinical presentations — classified by extent of disease:
Board pearl: Neonatal HSV can present WITHOUT vesicular skin lesions in up to 40% of CNS and disseminated cases — absence of vesicles does NOT rule out HSV
Typical onset: SEM at 1–2 weeks of life; CNS at 2–3 weeks; disseminated at end of first week
Must maintain high index of suspicion in any ill-appearing neonate — delay in acyclovir initiation dramatically worsens outcomes
History — Maternal and Perinatal Risk Factors
The maternal history is the single most important clue, yet ~60–80% of mothers of affected neonates have NO known history of genital herpes.
Primary maternal genital HSV infection near delivery → highest transmission risk (25–60%) — mother lacks protective antibodies, high viral shedding
Recurrent maternal genital HSV → much lower transmission risk (~2%) — preexisting antibodies transferred to fetus
Prolonged rupture of membranes (>4–6 hours) with active genital lesions → ↑ risk
Use of fetal scalp electrodes or vacuum/forceps → disruption of neonatal skin → portal of entry
Board pearl: The MOST DANGEROUS scenario is a mother with a new PRIMARY HSV infection at the time of vaginal delivery — this is when cesarean delivery is most strongly recommended
Ask about: oral or genital lesions in mother or close contacts, history of HSV in sexual partners, fever/prodrome near delivery
Postnatal exposure: family member or healthcare worker with active oral herpes (cold sore) kissing/touching neonate
Physical Exam — Recognizing Neonatal HSV
Exam findings vary by disease classification and may be subtle initially:
SEM disease:
CNS disease:
Disseminated disease:
Vesicles on an erythematous base — scalp (especially at electrode site), face, trunk, extremities
Conjunctivitis, keratitis (eye involvement)
Ulcers on oral mucosa
Seizures (often focal), lethargy, irritability, poor feeding, bulging fontanelle, temperature instability
May or may NOT have concurrent skin vesicles
Mimics bacterial sepsis or shock: hepatitis (↑ AST/ALT), DIC, pneumonitis, multi-organ failure
Jaundice, abdominal distension, bleeding (coagulopathy)
Can deteriorate rapidly within hours
Board pearl: A sepsis-like picture in a neonate that does NOT improve with antibiotics — or worsens with liver failure/DIC — should trigger immediate consideration of disseminated HSV
Temperature instability (hypothermia or fever) is common
Vesicles may appear AFTER disease is already advanced — do not wait for them
Diagnostic Workup — What to Order and When
When neonatal HSV is suspected, initiate workup AND empiric acyclovir simultaneously — do not wait for results.
— CSF HSV PCR (most sensitive for CNS disease; can be negative early → repeat at 72 hours if initially negative and suspicion remains)
— Blood/plasma HSV PCR (sensitive for disseminated disease and viremia)
— CSF analysis: pleocytosis (may be lymphocytic or RBC-predominant), ↑ protein, ± low glucose
— LFTs: AST/ALT markedly ↑ in disseminated disease
— CBC with differential, CRP
— Coagulation studies (PT, aPTT, fibrinogen, D-dimer) — DIC screening
HSV PCR — the gold standard:
HSV surface cultures or PCR swabs: conjunctivae, mouth, nasopharynx, rectum, and any vesicle fluid ("surface cultures" help confirm infection and type)
HSV viral culture of vesicle fluid — still useful but slower than PCR
Board pearl: A negative initial CSF HSV PCR does NOT exclude CNS HSV — sensitivity is ~75–100% depending on timing; repeat if clinical suspicion is high
Additional labs:
Imaging and Additional Diagnostics
— Classic findings: temporal lobe involvement (more common in older children/adults), but neonates may show diffuse cortical and white matter changes
— Obtain in all suspected or confirmed CNS disease
MRI brain with diffusion-weighted imaging: Most sensitive neuroimaging for HSV encephalitis
Head CT: less sensitive, may show edema, hemorrhage, or low-density areas; used if MRI is not immediately available
EEG: may show periodic lateralizing epileptiform discharges (PLEDs), focal or multifocal seizures; obtain if seizures suspected
Chest X-ray: if pneumonitis is suspected in disseminated disease
Ophthalmologic exam: slit-lamp evaluation for keratitis, chorioretinitis — required in ALL neonatal HSV cases
Board pearl: ALL three forms of neonatal HSV require lumbar puncture with CSF HSV PCR — even SEM disease, because CNS involvement can be clinically silent initially
Liver ultrasound may be warranted in disseminated disease showing hepatic necrosis
Management — Empiric Acyclovir: The Most Important Intervention
Timely initiation of IV acyclovir is the single most critical step in managing suspected neonatal HSV.
— SEM disease: 14 days
— CNS disease: 21 days minimum
— Disseminated disease: 21 days minimum
— Ensure adequate IV fluids; monitor BUN, creatinine, and urine output
Acyclovir IV 20 mg/kg/dose every 8 hours — this is the standard neonatal dose (higher than adult dosing per kg)
Start empirically at FIRST SUSPICION — do not wait for PCR results or vesicle appearance
Duration depends on disease classification:
Board pearl: Before stopping acyclovir in CNS disease, repeat the CSF HSV PCR — if still positive, continue IV acyclovir until CSF PCR is negative
Adequate hydration is essential — acyclovir can crystallize in renal tubules → nephrotoxicity
Monitor absolute neutrophil count (ANC) — acyclovir causes neutropenia; may need dose adjustment
Clinical tip: If a neonate is being evaluated for late-onset sepsis and is ill-appearing, consider adding acyclovir to the empiric antibiotic regimen (ampicillin + gentamicin + acyclovir)
Management — Suppressive Therapy After Acute Treatment
Following completion of parenteral acyclovir, oral suppressive therapy improves outcomes:
— If ANC <500/µL → hold acyclovir, recheck in 1 week; resume when ANC recovers
Oral acyclovir 300 mg/m²/dose TID for 6 months after completing IV therapy for ANY category of neonatal HSV
Purpose: suppresses viral reactivation, reduces recurrent skin lesions, and improves neurodevelopmental outcomes (particularly in CNS disease)
Landmark CASG (Collaborative Antiviral Study Group) data showed improved neurodevelopmental outcomes at 12 months in CNS disease group receiving suppressive therapy
Monitor ANC every 2–4 weeks during oral suppressive therapy — neutropenia is the primary adverse effect
Board pearl: Suppressive oral acyclovir is given for 6 months regardless of whether the disease was SEM, CNS, or disseminated
Educate family: oral acyclovir does NOT eliminate the virus — HSV establishes latency in neural ganglia
Close follow-up with pediatric infectious disease during suppressive therapy
Supportive Care and When to Involve Subspecialties
Neonatal HSV management requires a multidisciplinary approach:
— Pediatric infectious disease: ALL cases
— Pediatric neurology: CNS disease, seizures
— Pediatric ophthalmology: ALL cases (eye exam at diagnosis and follow-up)
— Pediatric hepatology: if hepatic failure
NICU admission for all confirmed or strongly suspected cases — continuous cardiorespiratory monitoring
Seizure management: phenobarbital is first-line for neonatal seizures; continuous EEG monitoring if seizures suspected
Coagulopathy/DIC in disseminated disease → fresh frozen plasma, cryoprecipitate, platelet transfusions as needed
Respiratory support for pneumonitis — may require intubation and mechanical ventilation
Hepatic failure → monitor glucose (risk of hypoglycemia), ammonia, coagulation factors
Subspecialty involvement:
Clinical tip: Involve palliative care early in severe disseminated disease with multi-organ failure — mortality can exceed 30% even with treatment
Contact isolation precautions until lesions have crusted
Age-Specific Considerations — Neonatal Period
— Congenital HSV is exceedingly rare but has the worst prognosis
— Disseminated: median onset ~day 5–7 (earliest)
— SEM: median onset ~day 7–14
— CNS: median onset ~day 14–21 (latest)
HSV in the first 48 hours of life → suspect in utero (congenital) infection → triad: skin vesicles/scarring at birth, eye findings (chorioretinitis, microphthalmia), CNS involvement (microcephaly, intracranial calcifications)
Most neonatal HSV presents between days 3–28 of life:
Board pearl: A well-appearing neonate with a single vesicle still requires full HSV workup + empiric acyclovir — SEM can rapidly progress to CNS or disseminated disease if untreated
Premature infants are at ↑ risk for severe disease due to immature immune function and lower transplacental antibody transfer
In neonates born to mothers with known active primary HSV, even without symptoms → obtain surface cultures at 24 hours of life and blood HSV PCR; some experts initiate empiric acyclovir pending results
Age-Specific Considerations — Beyond the Neonatal Period
— Treat with oral acyclovir if started within 72 hours of symptom onset; main risk is dehydration
— Key distinction: This is NOT neonatal HSV — different age, different management, different prognosis
HSV gingivostomatitis in infants and toddlers (typically 6 months–5 years) is common and usually self-limited — this is a PRIMARY oral HSV-1 infection presenting with fever, drooling, painful vesicles/ulcers on gums and oral mucosa
HSV encephalitis beyond the neonatal period → classically involves temporal lobes → presents with fever, altered mental status, seizures, focal neurologic deficits
Eczema herpeticum: HSV superinfection in children with atopic dermatitis → widespread vesiculopustular eruption, fever → requires IV acyclovir if severe
Board pearl: Neonatal HSV (first 28 days) demands IV acyclovir 20 mg/kg/dose q8h; HSV encephalitis in older children uses IV acyclovir 10 mg/kg/dose q8h for 14–21 days — the neonatal dose is HIGHER
Complications — Morbidity, Mortality, and Long-Term Sequelae
Mortality without treatment:
Mortality WITH acyclovir:
Long-term neurodevelopmental sequelae (even with treatment):
Disseminated disease: ~85% fatal
CNS disease: ~50% fatal
SEM disease: rarely fatal but may progress to CNS/disseminated
Disseminated: ~30%
CNS: ~6%
SEM: ~0%
CNS disease: ~70% have some neurologic impairment — seizure disorders, intellectual disability, spastic quadriplegia, microcephaly
Disseminated with CNS involvement: similar to isolated CNS disease
SEM: generally normal neurodevelopment IF no progression occurs and suppressive therapy is given
Board pearl: Recurrent cutaneous lesions occur frequently after neonatal HSV SEM disease — each recurrence carries a small risk of CNS seeding → this is WHY 6 months of oral suppressive acyclovir is recommended
Ophthalmologic sequelae: chorioretinitis, cataracts, optic atrophy → can cause permanent vision loss
Hearing loss possible with CNS involvement
Emergencies and When to Escalate Care
Recognize clinical deterioration patterns that demand immediate action:
Neonate with vesicles + seizures → acute bilirubin encephalopathy is NOT the diagnosis — think HSV CNS disease → LP + acyclovir immediately
Sepsis-like neonate with ↑↑ AST/ALT (often >1,000 IU/L), DIC, and negative bacterial cultures → disseminated HSV until proven otherwise → start acyclovir NOW
Board pearl: Markedly elevated hepatic transaminases (AST/ALT in the thousands) in a septic-appearing neonate with coagulopathy is a classic board trigger for disseminated HSV
Respiratory failure from HSV pneumonitis → intubation, ventilator management
Status epilepticus → airway protection, IV lorazepam/phenobarbital, continuous EEG
Renal dysfunction from acyclovir → ensure hydration, adjust dosing interval, consider nephrology consultation
If LP cannot be performed immediately (e.g., hemodynamic instability, coagulopathy) → do NOT delay acyclovir — treat first, LP when safe
Transfer to tertiary center with NICU if not already at one
Key Differentials — Vesicular Lesions in a Neonate
Not every vesicle in a neonate is HSV, but HSV must be excluded first:
Erythema toxicum neonatorum: benign, common (up to 50% of term neonates), erythematous macules/papules/pustules with eosinophils on Wright stain — NO vesicles on erythematous base; appears day 1–3, self-resolves
Transient neonatal pustular melanosis: ruptured vesicopustules → collarette of scale + hyperpigmented macules; neutrophils on Wright stain; benign, more common in dark-skinned infants
Varicella: if maternal varicella occurs 5 days before to 2 days after delivery → neonatal varicella risk → vesicles in different stages ("crops") → treat with IV acyclovir + VZIG
Congenital candidiasis: diffuse erythematous papules/pustules, often at birth, KOH prep shows budding yeast
Staphylococcal pustulosis/bullous impetigo: larger bullae, Gram stain shows gram-positive cocci in clusters
Key distinction: HSV vesicles are typically grouped on an erythematous base, may be hemorrhagic, and Tzanck smear shows multinucleated giant cells (though PCR is more sensitive and specific)
Key Differentials — Sepsis-Like Illness and Encephalitis in Neonates
— Board pearl: Enterovirus and HSV are the two most common causes of neonatal viral meningoencephalitis — if you suspect one, test for both
Bacterial sepsis (early- or late-onset): GBS, E. coli, Listeria → blood culture positive; HSV cultures/PCR negative; may overlap clinically → always consider HSV in culture-negative sepsis
Enteroviral sepsis: very similar presentation to disseminated HSV — hepatitis, myocarditis, DIC; enteroviral PCR of blood and CSF helps distinguish; often seasonal (summer/fall)
Metabolic crises: urea cycle defects, organic acidemias → may present with lethargy, seizures, liver dysfunction → check ammonia, lactate, blood gas, newborn screen
Congenital CMV: chorioretinitis, periventricular calcifications, hepatosplenomegaly, microcephaly → more indolent presentation; CMV PCR of urine/saliva
Bacterial meningitis: CSF culture/Gram stain positive; HSV PCR negative
Key distinction: The combination of liver failure (transaminases in thousands) + DIC + vesicles in a neonate = HSV disseminated disease until proven otherwise — do not wait for confirmatory testing to treat
Prevention — Maternal and Obstetric Strategies
Cesarean delivery is recommended when active genital HSV lesions or prodromal symptoms (pain, tingling) are present at the time of labor — reduces (but does not eliminate) transmission risk
Antiviral suppressive therapy in pregnancy: acyclovir or valacyclovir from 36 weeks gestation in women with recurrent genital HSV → reduces outbreaks at delivery and need for cesarean
Avoid fetal scalp electrodes and operative vaginal delivery (vacuum, forceps) when maternal HSV is known or suspected → reduces disruption of neonatal skin barrier
Board pearl: Cesarean delivery is MOST beneficial when the mother has a primary HSV outbreak at delivery; the benefit is smaller (but still recommended) for recurrent outbreaks with active lesions
Artificial rupture of membranes should be avoided if active genital HSV is suspected
Postnatal prevention: anyone with active oral HSV (cold sore) should NOT kiss the newborn and should use hand hygiene; healthcare workers with herpetic whitlow must not handle neonates
Screening, Surveillance, and Follow-Up After Neonatal HSV
— Type-specific HSV serologies may be offered to pregnant women with no history of HSV whose partner has known genital herpes
— Neurodevelopmental follow-up: early intervention referral, developmental assessments
— Ophthalmology follow-up: serial eye exams for chorioretinitis, cataracts
— Audiology: ABR at diagnosis and follow-up (CNS disease → hearing loss risk)
— Serial head imaging (MRI) in CNS disease
There is NO routine universal prenatal serologic screening for HSV recommended in the U.S. (unlike HBV, HIV, syphilis)
Asymptomatic neonates born to mothers with active primary HSV and vaginal delivery → obtain HSV surface cultures + blood HSV PCR at 24 hours of life; some experts recommend empiric acyclovir pending results
After completing neonatal HSV treatment:
Board pearl: Repeat CSF HSV PCR at end of 21-day IV treatment for CNS disease — if still positive → continue IV acyclovir until negative
Monitor ANC biweekly during 6-month oral suppressive therapy
Family Counseling and Psychosocial Considerations
— HSV is very common in adults (~50–80% seropositive for HSV-1; ~12–20% for HSV-2) — many carriers are asymptomatic
— Transmission often occurs from a mother who did not know she was infected
— Neonatal HSV is NOT the parents' "fault" — frame it as an unlucky circumstance
— SEM disease treated promptly → excellent prognosis
— CNS/disseminated → significant risk of neurodevelopmental sequelae; early intervention services
Parents of a neonate diagnosed with HSV often experience guilt, fear, and stigma — sensitive, nonjudgmental counseling is essential
Key education points:
Discuss prognosis honestly:
Explain the rationale for 6 months of oral acyclovir suppression and the importance of adherence
Advise on recurrent lesion recognition — parents should watch for new vesicles and seek prompt evaluation
Clinical tip: Connect families with support groups and resources; HSV diagnosis in a neonate is emotionally devastating
Clarify that HSV is lifelong but manageable — child may need episodic or suppressive antiviral therapy later in life
High-Yield Associations and Rapid-Fire Facts
HSV-2 historically more common in neonatal HSV, but HSV-1 proportion is rising and now accounts for ~30–50% of cases
HSV-1 CNS disease may have BETTER neurodevelopmental outcomes than HSV-2 CNS disease
Maternal primary infection = highest transmission risk; maternal recurrence = low risk but NOT zero
~60–80% of mothers of affected neonates have NO history of genital herpes
Acyclovir dose in neonates: 20 mg/kg/dose IV q8h (higher than older children/adults)
Acyclovir toxicities: nephrotoxicity (crystal deposition), neutropenia
Tzanck smear: multinucleated giant cells → suggestive but NOT specific (also seen in VZV)
CSF in HSV encephalitis: lymphocytic pleocytosis, ↑ protein, RBCs may be present, normal-to-low glucose
Board pearl: Negative neonatal HSV surface cultures at <24 hours of life may reflect maternal contamination — repeat at ≥24 hours for accurate neonatal viral assessment
SEM disease without treatment → 70% progress to CNS or disseminated disease
Congenital (in utero) HSV → skin scarring, microcephaly, eye abnormalities AT BIRTH
One-Line Recap
Neonatal HSV presents as SEM (best prognosis), CNS (seizures, CSF pleocytosis), or disseminated (sepsis-like with massive transaminase elevation and DIC) disease — typically between days 3–28 of life, often from mothers with unrecognized infection — and demands IMMEDIATE empiric IV acyclovir 20 mg/kg/dose q8h (14 days for SEM, ≥21 days for CNS/disseminated with end-of-treatment CSF PCR confirmation for CNS disease) followed by 6 months of oral acyclovir suppression, with the critical teaching point being that skin vesicles may be ABSENT in up to 40% of CNS/disseminated cases, and any septic neonate with hepatic failure, coagulopathy, seizures, or culture-negative sepsis must be evaluated and empirically treated for HSV without delay.
Board Question Stem Patterns
10-day-old neonate with fever, lethargy, vesicles on scalp, seizure → diagnosis: HSV CNS disease → next step: LP + HSV PCR + start IV acyclovir 20 mg/kg/dose q8h immediately
6-day-old with sepsis-like illness, AST 3,500, DIC, negative blood cultures → think: disseminated HSV → next step: start acyclovir, send blood HSV PCR
Mother with first episode of genital vesicles at 39 weeks in active labor → next step: cesarean delivery
Term neonate born vaginally to mother with active recurrent genital HSV → management: surface cultures + blood HSV PCR at 24 hours; many experts start empiric acyclovir
CSF HSV PCR positive after 21 days of IV acyclovir → next step: continue IV acyclovir until repeat CSF PCR is negative
Neonate on day 18 of acyclovir with ANC 400/µL → next step: hold acyclovir, recheck ANC; resume when recovered
Well infant with grouped vesicles on erythematous base at 12 days of life → do NOT reassure → full HSV workup + empiric acyclovir
Board pearl: "Culture-negative sepsis" in a neonate that continues to deteriorate = neonatal HSV or enteroviral sepsis until proven otherwise
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