Dermatology MCQ - Viral Infections - Neonatal herpes

A 10-day-old neonate presents with fever, lethargy, poor feeding, and a vesicular rash scattered across the trunk and extremities. The infant was born via vaginal delivery to a mother with no reported history of genital herpes. Which of the following is the most common mode of transmission for this infection, and what is the most critical next step in management?

A) Transplacental transmission; initiate intravenous acyclovir
B) Postnatal exposure to a caregiver with active herpes labialis; obtain HSV PCR from cerebrospinal fluid
C) Perinatal exposure during delivery to maternal genital secretions; initiate intravenous acyclovir immediately
D) Nosocomial acquisition from hospital equipment; implement contact isolation and start antibiotics
E) Breastfeeding from a mother with herpetic lesions on the breast; suspend breastfeeding and start topical antivirals

Correct Answer: C) Perinatal exposure during delivery to maternal genital secretions; initiate intravenous acyclovir immediately

Explanation

This scenario describes neonatal herpes simplex virus (HSV) infection, a severe and potentially fatal condition with high morbidity if not treated promptly.

Key Clinical Features of Neonatal HSV:

• Timing: Symptoms typically appear 5-21 days postpartum.

• Presentation: Nonspecific signs (fever, lethargy, poor feeding) may precede or accompany skin findings. The vesicular rash is a crucial clue but may be absent in up to 40% of cases, especially in disseminated disease.

• Classification:

  • Skin, Eye, and Mouth (SEM) Disease: Limited to skin, eyes, and oral mucosa.

  • Disseminated Disease: Involves multiple organs (e.g., liver, lungs, brain) with high mortality.

  • Central Nervous System (CNS) Disease: Encephalitis with seizures, lethargy, and irritability.

Mode of Transmission:

• Most Common: Perinatal exposure to infected maternal genital secretions during vaginal delivery (>85% of cases). This can occur even if the mother has no known history of genital herpes, as asymptomatic viral shedding is common.

• Less commonly, transmission can be postnatal (e.g., from a caregiver with active herpes labialis) or intrauterine (rare).

Management:

• Empiric Intravenous Acyclovir: This is the most critical step. Immediate initiation of high-dose IV acyclovir (20 mg/kg every 8 hours) is required for any neonate with suspected HSV infection, even before confirmatory tests, to reduce mortality and neurologic sequelae.

• Diagnostic Workup:

  • HSV PCR of blood, cerebrospinal fluid (CSF), and surface swabs (vesicle, mouth, conjunctiva, rectum).

  • Lumbar puncture to evaluate for CNS involvement.

• Supportive Care: Respiratory and hemodynamic support as needed.

Why Not the Other Options?

• (A) Transplacental transmission: This is rare and causes congenital HSV infection (present at birth with skin lesions, microcephaly, or eye abnormalities), not onset at 10 days.

• (B) Postnatal exposure: This accounts for <10% of cases. While IV acyclovir is still needed, the most common route is perinatal.

• (D) Nosocomial acquisition: HSV is not typically spread through hospital equipment. Bacterial infections (e.g., Staphylococcus) would be more likely in this context, but the vesicular rash points to HSV.

• (E) Breastfeeding transmission: This is rare and requires herpetic lesions on the breast. Suspending breastfeeding is not sufficient; systemic antiviral therapy is critical.

Prognosis:

• Outcomes depend on early treatment and disease classification:

  • SEM disease (Skin, Eye, and Mouth disease): Low mortality with treatment, but may progress