Neonatal Herpes Presentation
Neonatal herpes simplex virus infection presents in three distinct patterns: disseminated multiorgan disease (25% of cases), CNS disease (35%), or localized skin-eye-mouth disease (40%), with most infants becoming symptomatic between 9-11 days of age. 1
Three Clinical Presentations
Disseminated Disease (25% of cases)
- Typical onset: 9-11 days of age
- Encephalitis occurs in 60-75% of these infants
- Vesicular rash present in only 60% of cases (critical pitfall—absence of rash does not exclude HSV)
- Respiratory distress is prominent, particularly in preterm infants 2
- Involves multiple organs: liver, adrenals, lung, kidney, spleen, brain 1
- Highest mortality risk—in preterm infants, disseminated disease is nearly universally fatal despite treatment 2
CNS Disease (35% of cases)
- Typical onset: 9-11 days of age
- Vesicular rash present in only 60% of cases 1
- Neurologic symptoms predominate: seizures (79% presenting symptom), irritability, lethargy 3
- CSF abnormalities in 72%: elevated protein and/or pleocytosis 3
- EEG abnormalities: background changes (56%), electrical paroxysms (41%) 3
Skin-Eye-Mouth Disease (40% of cases)
- Typical onset: 10-11 days of age
- Vesicular rash present in 80% of cases 1
- Even with treatment, cutaneous recurrences occur during first 6 months 1
- Can progress to disseminated or CNS disease if untreated
Critical Timing Considerations
88% of infants present by 28 days of age, with the majority within the first 2 weeks 4. In preterm infants specifically, presentation typically occurs within the first 2 weeks of life 2.
One-third of infants develop symptoms within 24 hours of birth, and 61% within 7 days 3. This early presentation suggests intrauterine or intrapartum transmission.
Atypical Presentations—The Diagnostic Pitfall
16% of infants present without classic signs (no seizures, vesicular rash, or critical illness requiring ICU admission) 4. These nonspecific presentations include:
- Fever
- Poor feeding
- Irritability
- Lethargy
All infants with nonspecific presentation were ≤14 days old and had CSF pleocytosis 4. This defines a high-risk group requiring aggressive evaluation even without classic findings.
Key Diagnostic Features by System
Cutaneous
- Vesicular lesions are NOT universal—present in only 60% of disseminated/CNS disease
- May present with atypical findings: irregular white atrophic patches, scattered erosions that rapidly evolve to vesiculopustular lesions 5
- Absence of skin findings should never exclude HSV from differential
Neurologic
- Seizures (most common presenting neurologic sign—79%) 3
- Irritability, lethargy
- Poor feeding at approximately 1 week of age 6
Respiratory
- Respiratory distress is consistent across all disease types, especially in preterm infants 2
- Viral respiratory cultures have high yield for documentation 2
Other
- Cyanosis/pallor/grayish skin (16%) 3
- Fever (only 7% at presentation—absence does not exclude disease) 3
High-Risk Maternal Factors
- Most mothers (72-100%) have NO history of genital herpes 3
- Asymptomatic cervical shedding accounts for majority of transmissions
- Primary maternal HSV infection in third trimester carries 30-50% transmission risk 1
- Recurrent maternal infection carries only 0-5% transmission risk 1
- Prolonged rupture of membranes >6 hours increases risk 1
Diagnostic Approach
When neonatal HSV is suspected, obtain cultures from:
- Blood
- Skin vesicles (if present)
- Mouth/nasopharynx
- Eyes
- Urine
- Stool/rectum
Positive cultures from any site >48 hours after birth indicates viral replication rather than contamination 1.
CSF HSV DNA PCR is the diagnostic test of choice for CNS disease—CSF cultures are usually negative 1. However, an initially negative CSF HSV PCR does not guarantee against subsequent neurological involvement 5.
Critical Clinical Pearls
- High index of suspicion required in ANY neonate <28 days with fever, irritability, lethargy, or poor feeding
- Vesicular rash is absent in 40% of serious HSV disease—never rely on its presence to make or exclude diagnosis
- Age ≤14 days + CSF pleocytosis = high-risk profile even without classic signs 4
- Preterm infants have particularly high mortality with disseminated disease despite treatment 2
- Respiratory symptoms are prominent and consistent across disease types 2
- Even "localized" skin-eye-mouth disease carries 2-6% risk of later neurologic sequelae 1