Transmission - The Unwanted Gift
- Perinatal (Intrapartum): The major route (~85%), occurring during passage through an infected birth canal (usually HSV-2).
- Other Routes:
- Intrauterine (Congenital): ~5%
- Postnatal: ~10%, via direct contact with an infected individual (e.g., oral HSV-1).
- Risk Factors for Transmission:
- Primary maternal infection near delivery (highest risk).
- Invasive fetal monitoring.
- Prolonged rupture of membranes.
⭐ Most neonates with HSV are born to mothers who are asymptomatic and have no known history of genital herpes.
Clinical Picture - The Deadly Triad

- Neonatal HSV manifests in three overlapping patterns. Early diagnosis is critical as untreated mortality is high.
| Feature | Skin, Eye, Mouth (SEM) | CNS Disease | Disseminated Disease |
|---|---|---|---|
| Presentation | Localized vesicles | Seizures, lethargy, poor feeding | Sepsis-like, shock, hepatitis |
| Onset | 10-12 days | 16-19 days | 10-12 days |
| Mortality (Untreated) | Low, but high morbidity | ~50% | >85% |
| Key Features | Vesicular clusters on skin, conjunctivitis, ulcerative oral lesions. | Temporal lobe involvement, abnormal CSF. | Multi-organ failure (liver, lungs, adrenals), DIC. |
Diagnosis - The Viral Verdict
Prompt and accurate diagnosis is critical. The primary method involves viral detection via PCR.
- Gold Standard: HSV PCR is the test of choice, offering high sensitivity and specificity.
- Essential Samples: Obtain from multiple sites to maximize yield.
- Surface: Swabs from skin/vesicles, conjunctiva, oro- and nasopharynx.
- Systemic: CSF (mandatory if CNS disease is suspected), and whole blood.
- Essential Samples: Obtain from multiple sites to maximize yield.
- Supportive Findings:
- CSF Analysis: Reveals lymphocytic pleocytosis with elevated protein.
- LFTs: Elevated transaminases are a key marker for disseminated disease.
⭐ Exam Pearl: While viral culture was historically used, HSV PCR is now the superior and standard method, especially for CSF, where it is the most sensitive test for HSV encephalitis.
Management - Acyclovir's Ace
-
Primary Therapy: IV Acyclovir
- Dose: 60 mg/kg/day IV, divided every 8 hours (q8h).
- Duration: Varies by disease classification:
- Skin, Eye, Mouth (SEM) disease: 14 days.
- CNS or Disseminated disease: 21 days.
-
Supportive Care
- Essential for managing hydration (IV fluids), respiratory failure, and seizures.
-
Suppressive Therapy
- Oral acyclovir is recommended for 6 months post-treatment for infants with CNS or SEM disease to improve neurodevelopmental outcomes.
⭐ Untreated disseminated neonatal HSV has a mortality rate exceeding 85%. Early acyclovir is life-saving.
High‑Yield Points - ⚡ Biggest Takeaways
- HSV-2 is the most common cause, typically transmitted intrapartum.
- Presents as a triad: Skin-Eye-Mouth (SEM) disease, CNS disease, or disseminated disease.
- Disseminated HSV mimics neonatal sepsis and carries the highest mortality.
- Gold standard diagnosis is HSV PCR on CSF, blood, and vesicular fluid.
- Treatment is high-dose IV Acyclovir for all forms.
- C-section is indicated for mothers with active genital lesions during labor.
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