Overview
Definition:
Varicella zoster virus (VZV) exposure in the NICU refers to contact between a neonate, particularly those who are immunocompromised or premature, and an individual with active varicella (chickenpox) or herpes zoster (shingles)
This poses a significant risk of transmission and severe disseminated disease in neonates.
Epidemiology:
VZV is highly contagious, with a high attack rate in susceptible individuals
Neonates born to mothers with no prior immunity are at highest risk
Incidence varies by vaccination status of the community and maternal immunity
Approximately 1-2% of pregnant women are susceptible
VZV infection in late pregnancy can lead to severe neonatal varicella.
Clinical Significance:
Neonatal varicella can be life-threatening, with mortality rates as high as 30% in disseminated disease
The NICU environment, with vulnerable infants and close proximity, amplifies the risk of outbreaks
Prompt identification of exposure and appropriate prophylaxis are critical to prevent severe illness, maternal-fetal transmission, and nosocomial spread.
Risk Assessment And Exposure Classification
Definition Of Exposure:
Any neonate in the NICU who has been in contact with a person with VZV rash, including those with varicella or herpes zoster, is considered exposed.
Timing Of Exposure:
Significant risk if exposure occurs within 10 days before to 5 days after birth (for maternal infection) or any direct contact with an infectious individual in the NICU.
Neonatal Susceptibility:
Neonates are most susceptible if they are born prematurely (gestational age < 28 weeks), have low birth weight, or are immunocompromised (e.g., receiving chemotherapy, steroids)
Maternal immunity is protective for about 6 months in term infants but less so in preterm infants.
Exposure Classification:
Categorized based on the source of infection (varicella vs
zoster), proximity of contact, duration of contact, and immune status of the neonate
Zoster in a susceptible neonate poses a lower but still significant risk compared to varicella.
Prophylaxis Protocols
Indications For Prophylaxis:
Prophylaxis is indicated for all neonates exposed to VZV, especially if they are premature, immunocompromised, or born to a susceptible mother, and have not been previously infected or vaccinated.
Postexposure Prophylaxis Options:
Two main options: VariZIG (Varicella-Zoster Immune Globulin) and antiviral therapy (Acyclovir).
VariZIG Administration:
Recommended for all susceptible neonates with significant exposure
Administered intramuscularly within 96 hours of exposure, ideally as soon as possible
Dose is 12.5 IU/kg body weight
If exposure is recognized more than 96 hours after exposure, VariZIG may still be considered if the neonate remains susceptible and at high risk.
Antiviral Therapy Acyclovir:
Acyclovir (10 mg/kg per dose IV every 8 hours for 7 days) is an alternative or adjunct to VariZIG, especially for neonates with confirmed exposure and risk factors, or if VariZIG is unavailable
It is effective in preventing or modifying VZV disease.
Management Of Exposed Neonate
Immediate Actions:
Isolate the exposed neonate immediately
Alert the infection control team and neonatology/pediatric infectious disease team.
Monitoring For Rash:
Close monitoring of the neonate for the development of vesicular rash for at least 21 days (or up to 28 days if VariZIG was given).
Diagnostic Confirmation:
If rash develops, obtain lesion scrapings or vesicle fluid for viral culture, PCR, or direct immunofluorescence assay (DFA) to confirm VZV
Serological testing may also be performed.
Treatment If Rash Develops:
Initiate intravenous acyclovir at 15 mg/kg per dose every 8 hours for 10-14 days or longer for disseminated disease, with prompt consultation with pediatric infectious diseases specialists
Supportive care is crucial.
Infection Control Measures In Nicu
Isolation Procedures:
Place exposed neonates in contact and airborne precautions until 21 days (or 28 days if VariZIG administered) after last exposure, or until rash resolves if they develop VZV
If they develop VZV, they should be isolated for a minimum of 7 days after rash onset and until all lesions have crusted.
Staff Screening And Management:
Healthcare workers with no evidence of VZV immunity (no vaccination or prior infection) should be excluded from NICU duties if they have been exposed
They should receive prophylaxis (VariZIG or Acyclovir) and be monitored.
Environmental Cleaning:
Thorough cleaning and disinfection of the NICU environment, including isolettes, equipment, and common areas, to prevent environmental contamination.
Family And Visitor Screening:
Screen all visitors and family members for symptoms of VZV
Those with active rash should be excluded from the NICU and deferred from visiting until they are no longer infectious.
Key Points
Exam Focus:
Key focus areas for DNB/NEET SS include: risk factors for severe neonatal varicella, indications for VariZIG, dosage and timing of VariZIG, indications and dosage for IV acyclovir, duration of isolation, and importance of maternal immunity.
Clinical Pearls:
Always assume susceptibility in preterm infants and immunocompromised neonates
Early identification of exposure and prompt initiation of VariZIG are paramount
Multidisciplinary approach involving neonatology, infectious diseases, and infection control is essential.
Common Mistakes:
Delaying prophylaxis, incorrect dosing of VariZIG or acyclovir, inadequate isolation precautions, and underestimating the severity of neonatal varicella
Failing to consider maternal immunity status in risk assessment.